# assetType (asset type) The `assetType` is the **type of types** — the meta-type that every `<typename>.assetType/` folder is an instance of, including itself. A `<typename>.assetType/` folder declares a new asset type called `<typename>`: its on-disk shape, its identity rule, and the structural contract instances of the type must satisfy. This type is self-hosting. `assetType.assetType/` conforms to its own schema — a `type.yaml` plus a `README.md` — so the type system is defined in terms of itself rather than a hidden engine special-case (the same way a C compiler is written in C). Every asset in the engine, including each `.assetType` definition, now resolves to a registered assetType: a `.material` resolves to `material.assetType`, and `material.assetType` resolves to `assetType.assetType`, which resolves to itself. ## Why it exists Assets used to be mapped to their type *implicitly*, by matching the folder suffix against a name-keyed registry. That match carried no stored link: nothing on a `Foo.material` recorded *which* `material.assetType` it was written against, so two worlds shipping a same-named type could silently disagree. Making `assetType` a real, resolvable asset closes that gap — the link from an asset to its type is now an explicit reference pinned in the asset's `.refs` sidecar (`via: "asset_type"`), exactly like every other dependency. ## Where it lives - Source: `/zero/source/.../<typename>.assetType/` - Identity: `<typename>` (the `.assetType` suffix strips from the identity; the folder retains the suffix on disk). - Folder shape: - `type.yaml` — the structural spec the validator reads. **Required.** - `README.md` — type-level documentation. **Required.** - `about.yaml` — three short plain-language texts saying what the type is for (see "Say what your type is for" below). Every built-in type ships one. - `behavior.luau` — optional behavior/scaffolding module. - `template/` — optional canonical placeholder body the templater copies into a new asset of the type. - `<name>.module/` — optional shared code the type ships to **every instance** of it, conventionally `shared.module/` (see below). ## Shared code its instances reach (`asset.containing` + `.modules`) A type ships code every instance of it uses by declaring the modules in its own `behavior.luau`, as a map of tracked `require`s: ```luau -- inside <typename>.assetType/behavior.luau M.modules = { shared = require(".shared") } -- the sibling shared.module/ ``` An instance reaches it with one location-independent line: ```luau -- inside any foo.<typename>/init.luau local api = asset.containing(__FILE__).modules.shared ``` `__FILE__` is the chunk's own VFS path; `asset.containing` resolves the calling asset, and `.modules.<name>` follows the instance's pinned `typeRef` (the type's **guid**, recorded in the instance's `.refs` as `via = "asset_type"`) to the module its type declares. Because resolution follows that link rather than a category name, the same line in an instance of a different type resolves to that type's module, and identically-named modules in two types never collide. `asset.typeRef(target)` reads that guid for any target; `asset.resolve(asset.typeRef(target))` gives the full `AssetRef<assetType>`. See `assetTypes/README.md` § "Shared code: type-owned modules" for the full mechanism. ## How to create one Authoring a new asset type is just creating a `<typename>.assetType/` folder under `/zero/source/`. The engine registers `<typename>` as a category **the moment the folder is written** — no engine restart, no Rust change, and it works for built-in (`@builtin/assetTypes/`) and user-defined types identically. Once `<typename>` is registered, `<name>.<typename>/` folders are recognised as assets of that type and resolve their `asset_type` link back to this definition. Creating a `<name>.<typename>/` folder *before* its `<typename>.assetType/` exists fails fast: the suffix has no registered type, so the folder can't be a valid asset. Author the type first. ## Say what your type is for (`about.yaml`) Every type carries a small `about.yaml` beside its `type.yaml`, and the README you write for the type documents how to author an asset of it. Both are required, and both are meant to be written as you make the type, while you know what it is for. `about.yaml` answers three questions in plain words, one key each: ```yaml intent: "Sets the typeface of the text in your game: UI, labels, signs and 3D lettering." function: "A font, from a TTF, OTF or WOFF file, made available to all of Zero's text, including 3D text." usage: "You choose it by name for your UI or your text, and the text appears in that typeface." ``` - **`intent`** is what the type is for in someone's game. Name the whole range of things it covers, in the words a game maker would use for them. - **`function`** is how it works today: what an asset of the type is made of and what the engine does with it. - **`usage`** is what a person or an agent does with one: how they pick it, place it, call it, or hand it to something else. A few habits keep it useful. Write about the type as a whole, so the text holds for every asset of it, and leave out any one asset's name. Say what the type does right now. Stay with words a game maker would say, and mention a file name or a call only where a game maker would know it. The limits are in bytes: `intent` 800, `function` 1500, `usage` 1200. Each is generous, and a few sentences usually say it. Why bother: agents working in a world read these three texts to learn what your type is for, so they reach for it when it fits and use it the way you meant. People searching find the type by what they want to make, and the three texts let them tell at a glance whether it is the one they need. `asset.create("assetType", name)` scaffolds the file with all three keys, and a README whose first paragraph is a `[[describe]]` note. Each value starts with `[[describe]]` followed by a note on what to write; replace the whole value with your own words. A value or a README line that still starts with `[[describe]]` counts as not written yet, which the push's check of each asset it carries against its type reports, naming the file. A type you leave as it was is not asked, so older types stand. Many types at once, or one you would rather not write by hand: `services describe` lists the types that lack these texts and what filling them costs, and `{ mode = "all" }` writes them into the same files, where you edit them like anything else you wrote. Where the texts show up: `asset.inspect("<typename>", "assetType")` returns them as `detail.about`, `assetTypeRef:getAbout()` returns them as a table with the keys `intent`, `function` and `usage`, the type's `types/<typename>` guide page ends with an "About this type" section holding them, and the Inspector's Type section lists them at the top. The guide page is this README plus that section, so a README that explains the type well and an `about.yaml` that says what it is for read well together. ## Ask your assets to say what they are A type can ask each of its assets to carry a description: a file, written by the author or generated, that says what that asset is and what it is for. The people and agents who find an asset read it to decide whether it fits, and the author knows what it is for at the moment of making it. **1. Declare the file with a `described` check.** This is the whole requirement: ```yaml files: required: - path: "README.md" # any file name works kind: "file" content: - { check: "described", message: "Say what this widget is for and where it goes." } ``` With that in place: - An asset whose file is missing, empty, or still has a line starting with `[[describe]]` does not meet the type's requirements. `asset.validate` names it, `zm status` and `world.publishBlockers()` list it, and a push that carries it is refused with `message`. - `services describe` finds it (`mode = "find"` lists it and the price) and can write the description for it (`mode = "all"`). It writes only this file. For a YAML file that holds several texts, name the keys and their limits in bytes, the way this type does for `about.yaml`: ```yaml content: - check: "described" keys: - { key: "intent", max_bytes: 800 } - { key: "usage", max_bytes: 1200 } message: "Write intent and usage." ``` `headings` names sections a Markdown file must have. `assetTypes/README.md` has the full check. **2. Optionally, steer what gets generated with a `describe:` block:** ```yaml describe: guidance: "Say what the widget shows, what input it reacts to, and where it fits in a UI." examples: - "<identity of an asset of this type whose description reads well>" ``` `guidance` says what a description of your type covers, and `examples` names assets whose descriptions show the shape you want. Without the block, generation still works from the general describing guide and the check's `message`. An example is an asset of your type in the library whose description is a true, written one, never a scaffold's placeholder, and never the asset being described. When the library has none, leave `examples` empty rather than name one that is not. A type whose assets the model cannot perceive (a sound it cannot hear, a motion it cannot see) says so in `guidance`: the description comes only from what the asset's own files state, such as its name and the `.metadata` where a generation service records the prompt that made it, and when they state nothing the model answers `cannot` with that reason. `services describe` then fails that one asset with the reason and leaves its file as it was. **3. Start the file unwritten in your template.** Put a heading and one line that starts with `[[describe]]` and a short note on what to write, in `template/<file>`, so a new asset starts unwritten rather than with text that only looks written. Do not put example content in it: every new asset carries the template verbatim, and the same text on many assets makes them impossible to tell apart in search. Types whose assets say what they are through their own content (a mesh, a texture, a sound) leave this out: declare nothing and nothing is asked. ## The `behavior.luau` contract `behavior.luau` is the type's code. It returns ONE table, and the keys below are the ones the framework reads off it for EVERY type — the surface you get by declaring them. Anything else on the table is your own: reachable by name through `require("@builtin::assetTypes.assetType.shared.ref").loadTypeModule("<typename>")` for a system that knows your type (`computeShader` publishes `dispatchKey` that way), and never called by the framework. ```luau local M = {} M.ref = { ... } -- methods on every AssetRef of this type M.modules = { ... } -- shared code the instances reach M.global = {} -- reserved key; ship the empty table function M.onCreate(name, opts) ... end return M ``` ### The tables | Key | Shape | What the engine does with it | |-----|-------|------------------------------| | `M.ref` | `{ [name] = function(self, ...) }` | Every function becomes a method on every `AssetRef` of this type: `ref:name(...)`, with `self` the ref. This is how a type gives its instances an API. Two names in here are contracted — see below. | | `M.modules` | `{ [name] = require(".sibling") }` | Shared code the type's instances reach through `asset.containing(__FILE__).modules.<name>`, resolved by the instance's pinned `typeRef` guid. See the section above. | | `M.refShapes` | `{ [method] = "TypeName" }` | Declares the result type of a `M.ref` method so the LSP can check what a call site does with it. See the `M.refShapes` section below. | | `M.events` | an events schema | The events an ASSET of this type fires, declared the way a component declares its own. Readers subscribe through `ref.events.<name>:connect(...)`; firing authority stays with the type. Keyed by the asset's guid, so every resolver of the same asset shares the signals and a re-resolved ref re-attaches to subscriptions already there. | | `M.namePattern` | a Lua pattern string | The name shape `asset.create` enforces for instances of this type, replacing the default `^[A-Za-z][A-Za-z0-9_]*$`. | | `M.global` | `{}` | Reserved. Ship the empty table. | ### The lifecycle hooks Each is optional; a type that omits one costs nothing. The engine calls them: | Hook | Signature | When it fires | |------|-----------|---------------| | `M.onCreate` | `(name, opts) -> { [filename] = contents }` | On `asset.create("<type>", name, opts)`. Returns the files that scaffold the new instance, as a map of relative path to contents; the framework writes them. The `opts` type annotation is the schema `asset.create` validates the caller's arguments against, so annotate it. | | `M.onReplace` | `(dest, files) -> { [filename] = contents }` | On an `asset.create` that writes over an asset already at `dest`, after `onCreate`. Receives the files `onCreate` produced and returns the files to write, so a type that re-derives its content (a rig re-imported from its source file) can carry what an author added to the asset it replaces. Optional. | | `M.onRegister` | `(self)` | Once per instance, the first time it registers: on `engine.onWorldLoaded` for instances already in the world, immediately on a live `asset.create`, and when an instance arrives after that sweep (installed, pulled, or synced from a peer). Guarded by the instance's path, so a double trigger never double-registers. An instance that leaves the runtime releases the guard, so one arriving at the same path again registers. This is what makes "write an asset into the world and it takes effect live" work for content that registers into a runtime registry. The `@builtin` library is excluded from the sweep. | | `M.onChange` | `(ref, change)` | On every VFS write to a file INSIDE one of this type's instances. `change` is `{ path, asset, type, kind, origin }`: `kind` is `"edited"` or `"seeded"`, `origin` is `"local"` or `"remote"` (an importer runs on the originator only). **Filter on `change.path`**: the hook fires for any file under the folder, so act on the one you care about. It runs as its own task and may wait on what it reads: a `vfs.read` of bytes only the blob store holds (a binary file on the web build) fetches them. The writes to one asset reach the hook in the order they were made, each once the hook before it has finished. A re-entrancy guard suppresses writes back into the same asset routed inline from the hook, and a write the hook makes is routed on a later frame like any other, so the hook must be convergent on its own: diff the meaningful state and short-circuit while your own regeneration is in flight. | | `M.onDelete` | `(ref)` | When an instance of this type leaves the runtime: it is deleted, or the engine swaps away from the world binding that held it. Its files are gone from `/zero/source` by then. A removal routed while the instance's `onChange` is waiting reaches `onDelete` once that hook, and every write queued behind it, has finished. On a swap the instance still exists in the world it belongs to, and a VFS write the hook makes reaches the world now bound. | | `M.validate` | `(assetRef) -> { { code, message, severity? } }` | On `asset.validate`, after the structural `type.yaml` check, for the type's own SEMANTIC validation. `severity` defaults to `"error"`; error-severity problems flip `ok` to false, warnings do not. A hook that raises or returns a non-table is itself reported as a `validate.hook_failed` error. `world.push` runs this per user asset, so declaring it enforces your type's rules at publish time with no further wiring. | ### The two contracted `M.ref` names Most `M.ref` methods are your type's own surface: name them what you like, return what you like. Two are read by the engine and mean the same thing for every type, so their shape is fixed: - **`instantiate(self, target?, opts?) -> (root, idMap)`** — makes an instance part of the scene. Defining it is the whole opt-in: `ref:canInstantiate()` is true exactly when it exists. Its **return is a contract** — see the next section. - **`inspect(self) -> detail`** — the type-specific half of `asset.inspect`. See its section below. ### Names a type cannot shadow Some keys resolve on every `AssetRef` before per-type dispatch, so an `M.ref` entry of the same name is never reached: `canInstantiate`, `getSource` / `getBytes` / `getText`, `exists`, `deps`, `meta`, `runtime`, `events`, `modules`, `typeRef`, and the residency flags `has_backing_asset`, `has_runtime_changes`, `cpu_resident`, `gpu_resident`. These are the behaviours every asset must expose identically, which is why they win. ### Reloading A `behavior.luau` edit ripples to existing refs with no restart: dispatch reads `mod.ref` fresh each time and `require`'s cache is re-run in place. A type whose folder appears at runtime is picked up on the next dispatch — negative results are not cached either. ## The names your type's assets hold (`references:`) An asset that names another asset by a string depends on it: the named asset travels with it into a pack or a pull, and a name nothing answers to is an unresolved dependency `worldValidation` reports and the push gate refuses. The engine reads `require(...)` and the asset lookups on its own; a name your type's format or API carries anywhere else is one you declare, in `type.yaml`: ```yaml references: # A top-level key of this type's own files that holds a name (or a table of them). keys: - { key: "shader", type: "shader" } # A call's argument, counting from 1, wherever the call is written. args: - { call: "g:node", position: 2, type: "procNode" } # A field of the options table a call takes. fields: - { call: "fx.beam", field: "material", type: "material" } ``` `type` is the category the name resolves in, one of `asset.categories()`. An argument declared once per category, at the same `call` and `position`, takes the name from whichever category answers. A key or a field holds one category: declared again with another `type`, it takes the later one. The block is declared as the type registers, when the library or the world holding it is laid into the VFS, so every reference table reads it whatever script has or has not run. `asset.declareReferenceKey`, `asset.declareReferenceArg` and `asset.declareReferenceField` declare the same things from a script, for a surface that is no type's. ## What search does with your type (`indexing:`) A type declares what search embeds for its instances. **This is not optional and there is no useful default**: ZeroMind runs your declaration and adds nothing of its own, so anything you do not point at is absent from the index — silently, and for every instance of the type forever. Twenty types once shipped with no `indexing:` block and every instance of them was unfindable. A type whose instances are never searchable (a run record, a log) says so with `indexing: none`; every other type declares a recipe. A type without an `about.yaml` beside its `type.yaml` refuses every push that carries it, whether or not the push edited the type. Texts in it that are not written yet follow the rule every `described` file follows: they refuse the push that edits, stages or commits the type. Two words carry the whole thing, and they are the same two the search tool exposes: - **`identity`** — what an instance IS. For anything you can look at, that is the picture (`content:` + `modality: image`, matched directly by a text query). For everything else it is the authored text that says what it is. - **`capability`** — what it DOES and how it is made. Code, settings, the model-written summary of them. A type with no behaviour has no `capability` entry. A type with nothing to look at has no image. Leaving a slot empty is a statement; filling it with whatever happens to be lying around is not. The one you have to decide when authoring a type is: *for an instance of this, what is the thing a person would recognise it by, and what is the thing it does?* A texture answers "the image" and "its compression settings". A module answers "its README" and "its code". Write those two answers into `indexing:` and the rest follows. Three specifics worth knowing before you write one: - **`derive` is instructed by this type's own `README.md`.** A model reads an instance's source and writes a description; what it embeds is the description, not the source. It follows your README to know what it is looking at, so a type whose README says what its instances are gets good derivations for free. There is no prompt to name. - **`derive` loses detail.** It keeps the main technique and drops secondary ones. If the source is code you want searchable by its own vocabulary, declare the same files a second time as `capability` with `extractor: verbatim`. Two entries, same role, different failure modes. - **Never `source: { field: name }`.** A filename is one or two words with no usable embedding, and a corpus indexed that way answers "language runtime" with `say_runtime_2.soundClip`. `facets:` is the second stage: a `file:` embedded whole (`.metadata`, so keys nobody declared still get indexed) plus computed keys that state a value for every instance including `false` — the raw file can imply "not rigged" and can never say it. The full schema, every extractor and the facet sources are in [`assetTypes/README.md`](../README.md); the scaffolded block with inline guidance is in [`template/type.yaml`](template/type.yaml). ## A container whose contents work together (`system: true`) A type that is a container can say its contents are one working whole by declaring `system: true` at the top level of its `type.yaml`. `package` declares it: the components, modules, scenes and tools a package ships are parts of one system. The declaration is plain data, read from the decoded `type.yaml` (`require("@builtin::assetTypes.assetType.shared.declaration").of("package").system`), and a type that leaves it out is an ordinary type. ## What your type looks like (`preview:`) A type declares how its instances are pictured, and the engine makes the picture when something needs it: staging an instance whose `preview.png` is missing or pictures content it no longer holds queues a render, a view that shows the instance asks for one, and `ref:preview()` renders one on demand. An edit renders nothing on its own. Each `preview.png` records the content it pictured, which is how a stale one is told from a current one. The preview studio owns the light, the backdrop, the framing and the camera, and nothing in the world reaches it, so an instance pictures the same in every world. Declare one of four recipes: | `kind` | The picture is | Your type provides | |---|---|---| | `instantiate` | the asset stood in the studio through its own `instantiate` | `ref.instantiate` | | `image` | a file the instance holds, fitted to the frame, nothing rendered | `source.files`, the candidate files in order | | `surface` | the asset painted on a builtin mesh | `mesh`, and `ref.previewMaterial(self) -> { material }` | | `custom` | whatever `ref.preview(self, opts)` returns | `ref.preview` | ```yaml preview: kind: surface mesh: sphere ``` A scene-instantiable type that declares nothing still answers `ref:preview()` through its `instantiate`, but persists no picture: the declaration is what makes the engine keep one. List `preview.png` among the type's files so an instance may hold it. The picture is findable only when `indexing.content` names it. The two are separate statements, and neither is derived from the other: ```yaml indexing: content: - role: identity modality: image source: { file: "preview.png" } ``` `@builtin::assetTypes.assetType.shared.previewRecipe` reads the declaration; the scaffolded block with inline guidance is in [`template/type.yaml`](template/type.yaml). ## Typing a result from the instance (`M.refShapes`) Every method on `M.ref` is checked against the type its `--!return` names, and every asset of the type gets the same one. That is right for most methods and wrong for the ones whose result is shaped by the ASSET: a method answering one entry per child folder, per row of a config, per binding an input map declares. The widest true annotation for those is `{ [string]: Thing }`, and an indexer accepts every key — so a caller's typo reads as valid and nothing reports. `M.refShapes` lets the type state the result per instance. Each entry is `function(self) -> (typeExpression, source?)`: a Luau type expression for THIS asset, and the module whose type vocabulary the expression uses. Read the asset; never run it — stating a type must not take effect. ```lua -- inputMap.assetType/behavior.luau — the shipped example. -- `activate()` hands back one handle per control the map declares. M.refShapes = { activate = function(self): (string, string) local names = {} for _, control in ipairs(M.ref.controls(self)) do table.insert(names, control.name .. ": Handle") end if #names == 0 then return "", "" end return "{ " .. table.concat(names, ", ") .. " }", "@builtin::modules.zinput.scheme" end, } ``` With it, `map.jump:onPressed(fn)` resolves and `map.noexisting` is reported with the map's real controls. Without it, both pass silently. ### What the call site has to say A per-instance type is matched by the asset's IDENTITY, so it applies only where the reference the method is called on says WHICH asset. Two spellings do: ```lua -- a component field, whose declared default names the asset public = { map = Field.assetRef("inputMap", "@builtin::inputMaps.default", Sync) } local controls = public.map:activate() -- typed for THAT map -- an annotation, naming category and identity local m: AssetRef<"inputMap", "@builtin::inputMaps.default"> ``` `asset.resolve("<identity>", "<category>")` carries the CATEGORY, so the methods the category defines are checked on the result — but not which asset it found, so a per-instance result keeps the category's declared return. A reference that names no asset (`asset.resolve(someVariable)`, a value passed in as a parameter) carries neither, and calls on it are unchecked. That is the same rule everywhere: the checker states what the code states, and a name computed at runtime states nothing. ### The result is a value, not a binding The type belongs to the expression, so it travels the way any inferred type travels. Indexing the call's result is checked; stashing it in a module local and indexing it from another function is not, because the local's declared type is what carries across — and `any` (or no annotation) carries nothing: ```lua -- checked: `d.greting` is reported function awake() local d = public.dialogue:lines() d.greeting:say() end -- NOT checked: `lines` is a module local typed `any` local lines: any = nil function awake() lines = public.dialogue:lines() end function start() lines.greting:say() end ``` Bind what you need at the call site and the names stay checked in both places — the asset-derived type at the boundary, ordinary scoping after it: ```lua local lineGreeting = nil function awake() local d = public.dialogue:lines() lineGreeting = d.greeting -- `d.greting` is reported here end function start() lineGreeting:say() end ``` ### When nothing is reported and you expected something From a call site, a type that is correct and a type that was never published look the same: no diagnostic either way. `require("@builtin::assetTypes.assetType.shared.refShapes").published()` answers which it is. It returns two maps — the category surfaces, and the per-asset results keyed by identity and then by method: ```lua local shapes = require("@builtin::assetTypes.assetType.shared.refShapes").published() shapes.categories.dialogue --> "{ lines: () -> any, lineNames: () -> { string } }" shapes.returns.Shopkeeper.lines --> "{ browsing: Line, farewell: Line, greeting: Line, wares: Line }" ``` An identity absent from `returns` was never published for, which is a different thing from published-and-correct — and the reason to look here rather than at the call site. The answers are recomputed when an instance is written, so a control added to a map reaches the checker with no restart. Only types that declare `refShapes` are read per instance, and at most 64 assets of one type are — past that the type keeps its declared return and the engine log names what was dropped. ## The instantiate hook (`M.ref.instantiate`) — a contracted return A type opts into becoming part of the scene by defining `instantiate` on its `ref` table. That is the whole opt-in: `ref:canInstantiate()` is true exactly when the hook exists, so consumers offer a scene path — an `Asset.source` field, a viewport drop, a tool argument — by CAPABILITY rather than by a list of type names. Unlike `inspect`, this hook's **return is a contract**. A caller writes one piece of code against every instantiable type, so what comes back cannot vary by type: ```lua -- behavior.luau local Instantiable = require("@builtin::assetTypes.assetType.shared.instantiable") local M = {} M.ref = { instantiate = function(self, target, opts) local root = Instantiable.root(self, target, opts) -- IN: the base opts -- ... compose whatever this type is, under `root`, NOW ... return Instantiable.result(self, root, idMap) -- OUT: the contract end, } return M ``` **IN.** `target` is an owning entity ref: the instance lands under (or, for a hierarchy type, onto) that owner. With no target the type spawns a fresh root. `position`, `rotation`, `scale`, `name` and `temporary` mean the same for every type — `Instantiable.root` applies them to a root you mint, `Instantiable.place` to one you adopt, so you never re-read the spec. Honour more opts of your own if your type needs them, and document them in the hook's `--!arg` docs. **OUT.** Return `(root, idMap)` through `Instantiable.result`: - **`root`** — the composed root, as an `EntityRef`. Composition is **synchronous**: everything your type builds is live when you return, so the caller can parent to it and read its components in the same statement. Do not defer the work to a component's `awake` and return an empty shell — a root that is not live is refused. - **`idMap`** — the `originalId -> runtimeId` map naming what you spawned, or nil for a type with no addressable children (`result` normalises it to `{}`). **A caller never receives nil.** A component that re-composes your asset on every load keeps this map and passes it back in, which is how a cross-entity reference into the composition survives a reload. `AssetRef` runs every `instantiate` through `result` on the way out whether or not your type called it, so returning something else fails at your own call rather than handing a caller a nil root. Calling it yourself is still how you say what you return, and running it twice changes nothing. `@builtin::assetTypes.assetType.shared.instantiable`'s README is the full reference for both halves. ## The inspect hook (`M.ref.inspect`) `asset.inspect(ref)` resolves `ref`, builds a common envelope shared by every asset (`identity`, `name`, `guid`, `source`, `typeName`, `typeDefinitionPath`, `scope`, `origin`, `description`, `tags`), then calls the resolved type's own inspect hook — `M.ref.inspect(self)` on `behavior.luau` — for the type-specific `detail`. The hook returns *only* `detail`; the framework fills in everything else: ```lua -- behavior.luau local M = {} M.ref = { inspect = function(self) -- self.path is the asset's own folder. Parse the asset's OWN -- files — source text, a native payload header, its `.metadata` -- — never runtime state (a live component instance, a GPU -- upload, a compiled schema): inspect must work on an asset that -- hasn't been compiled, uploaded, or registered yet. return { -- type-specific fields, whatever this type wants to surface } end, } return M ``` A type that omits `M.ref.inspect` yields the generic record: the envelope alone, `detail = nil`. That's a valid, working state — not an error — but it means agents calling `asset.inspect` / `tools.use("assets","describe", ...)` on an instance of the type see only identity and scope, none of what makes an instance of it meaningful. Declaring the hook is what makes a type's instances inspectable for what they actually are. A hook that raises leaves `detail = nil` and sets `record.warning` to the error text — `asset.inspect` itself never raises for a resolved ref. ## Discovery - `asset.list("assetType")` — every registered asset type. - `asset.inspect("<typename>")` — the type's identity, source path, and this README, plus its `about.yaml` texts as `detail.about`. - `asset.resolve("<typename>", "assetType")` — the `<typename>.assetType` asset itself (used by the validator to find the type's `type.yaml`). ## Related - `assetTypes/README.md` — the full `type.yaml` schema and validator rules. - `@builtin::assetTypes.assetType.shared.instantiable` — the instantiation contract's shared implementation, both halves. - Every other `*.assetType/` here — the concrete types built on this meta-type. ## The Inspector a type ships Every type names the file its Inspector sections come from with `inspector: { type: "inspector.luau" }` in its type.yaml. `asset.create("assetType", name)` scaffolds the block and an `inspector.luau` whose Contents section lists an asset's files, built from `ctx.parts`. `asset.validate` on a type that names none reports `assetType.inspector_required` (an error for a `@builtin` type the engine's library authors; a warning for a world's own, and for one the library carries by reference, which the world that published it answers for), and one whose file does not load `assetType.inspector_invalid`. ## In the Inspector Type: what the type.yaml declares (suffix, container, primary files, the settings and inspector blocks), whether the type ships a behavior, how many instances it has, and **Open** for its files. Schema: the settings every instance carries, as read-only typed controls at their defaults (a type whose schema is per instance says where it is declared). Instances: a link to each of the first 20 assets of the type, and how many there are when there are more.

# preview Render an asset's preview in the preview studio: an isolated camera, lit only by its own three-point rig, over a neutral backdrop, that nothing in the scene reaches. `ref:preview()` renders any asset by the recipe its type declares under `preview:` in its `type.yaml`, and these are the primitives it calls: they spawn temporary entities, frame an offscreen camera over them, render one frame, read it back as a PNG, and tear the entities down. ## Surface - `preview.fromEntities(makeFn, opts?) -> PreviewResult` — run `makeFn` to instantiate entities, frame a camera to their bounds, render one offscreen frame, and return the still PNG. - `preview.fromRecipe(ref, recipe, opts?) -> PreviewResult` — render `ref` by a declared recipe: `instantiate` stands it through its own `instantiate`, `surface` paints the material its type's `ref.previewMaterial` returns on the recipe's mesh, and `image` fits a file the asset holds to the frame on the studio backdrop without rendering anything. - `preview.backdrop() -> { r, g, b }` — the studio backdrop's colour in a finished preview, 0-255. `PreviewResult` is `{ available, imageBase64?, rendered?, width?, height?, bounds?, stats?, reason? }` — `imageBase64` is the rendered PNG when `available` is true, and `reason` explains why when it is false. `opts` is `{ size? = { width, height }, angle? = { yaw, pitch } }`. ## Example local result = asset.resolve("gold", "material"):preview({ size = { width = 512, height = 512 } }) -- result.imageBase64 holds the rendered PNG (base64)

# scene_instantiable (module) The instantiation contract's shared implementation. An asset type opts into scene instantiation by defining `instantiate(self, target?, opts?)` on its behaviour `ref` table; this module carries the parts that mean the same thing for every type, so a caller writes ONE piece of code against all of them. ```lua local root, idMap = ref:instantiate(target?, opts?) ``` ## The contract **IN — the base opts.** `target` is an owning entity ref: the instance lands under (or, for a hierarchy type like a bundle, onto) that owner. With no target the type spawns a fresh root. `position`, `rotation`, `scale`, `name` and `temporary` place that root and mean the same for every type. `rotation` takes three numbers as pitch/yaw/roll in DEGREES, or four as a quaternion. A type may honour more opts of its own — `params` for a type built from declared inputs, `idMap` / `diff` / `sourceTag` for the bundle override contract — and says so in its own `instantiate` docs. **OUT — the two returned values.** Every type returns the same pair: - **`root`** — the composed root, as an `EntityRef`. Composition is **synchronous**: the root and everything the type built under it are live the moment the call returns, so a caller can parent to it, read its components and hand it on in the same statement. There is no frame to wait for and no callback. - **`idMap`** — the `originalId -> runtimeId` map naming what the composition spawned, `{}` for a type with no addressable children. **Never nil.** A component that re-composes the asset on every load (`Asset`) keeps this map and passes it back in, which is how a cross-entity reference into the composition — `SkinnedModel.skeletonRoot` pointing at a bone — survives a reload. The return is enforced, not merely described: `AssetRef` dispatches every `ref:instantiate(...)` through `result` on the way out, whether or not the type called it. A type that returns something else fails at its own call rather than handing its caller a nil root or a map that is sometimes absent. ## Exports - `M.root(self, target?, opts?) -> root` — stand the root entity for a type that spawns one: parented to `target`, born temporary when `opts.temporary`, named `opts.name` else the asset's own name, placed. - `M.place(root, opts?) -> root` — apply the placement opts to a root the type already has (the adopt path: a bundle exploding onto its target, a sceneModule reconciling under one). - `M.result(self, root, idMap?) -> (root, idMap)` — return through the contract. Checks `root` is a live entity ref, normalises a missing map to `{}`, and errors naming the asset type when either is something else. - `M.isOwned(opts?) -> boolean` — whether a component drives this call. The `Asset` / `SceneModule` components tag their own calls with `sourceTag`; they hold the reference and re-compose on every load. An untagged call came straight from `ref:instantiate(...)` and has no such owner. - `M.own(root, self, idMap?) -> root` — hand an already-composed root to an `Asset` component pointing at `self`, so the reference and its map persist and the composition is rebuilt on the next load. The component adopts the live composition rather than building a second one. - `M.check(value, constraint) -> ok, reason?` — the `sceneInstantiable` field-constraint validator, also registered under that kind on load. ## The field constraint `Field.instantiableRef` emits `constraint = { kind = "sceneInstantiable" }`, and this module registers the validator for it on load. Given a written value: 1. `nil` passes — the field is optional (no asset assigned). 2. Reads the value's identity — a bare string, or a table's `__ref` / `guid` / `identity` / `name`. 3. Resolves it (`asset.resolve(identity)` — any category) and asks the resolved ref `ref:canInstantiate()`: true iff the asset's type defines an `instantiate` method. This is what lets `Field.instantiableRef` accept by CAPABILITY rather than a hardcoded type list — a new scene-instantiable asset type is accepted the moment it defines the hook, with no edit to the field or its consumers.

# oceans A sea and the ground under it, as one package: the wave simulation, the surface that renders it, the seabed it is seen through, and the answer to "how high is the water here" that gameplay needs to float things on it. ```lua local Ocean = require("@builtin::systems.oceans.modules.ocean") Ocean.create({ preset = "gale" }) ``` That is a whole ocean — waves out to the horizon, foam on the breaking crests, a seabed below, and a surface that follows whoever is looking at it. To float something on it: ```lua local ocean = Ocean.forEntity(oceanEntityId) boat.position = { x, ocean:sampleHeight(x, z), z } ``` It is a building block. The sun the water glitters under, the ambient its foam sits in and the sky it reflects all come from the scene, through the same directional light and reflection probes every other material in the engine reads — so an ocean drops into a world that already has lighting instead of bringing a second set, and changing the scene's light changes the water with it. ## What it does The simulation is **spectral**: instead of animating individual waves, it builds the sea's energy across every wavelength and direction from an oceanographic spectrum, then inverse-transforms that into a height field. A real sea is what comes out — wind speed alone decides wave height, and it rises with wind the way a fully developed sea does, following the Pierson–Moskowitz law. It runs in **cascades** — independent wave fields over different patch sizes, each band-limited to its own range of wavelengths. A tile of roughly two kilometres carries the long waves and one of a few hundred metres the short ones; they sum into a surface with detail at every scale, and because the bands are disjoint no wavelength is synthesised twice. Above them a **Gerstner bank** adds the swell analytically, which no cascade can hold: a wave longer than its own patch has nowhere to live, and swell arrives from a distant storm on its own heading anyway. **Foam** is not painted on. It comes from the Jacobian of the wave displacement: where the surface folds over itself, the wave is breaking. Whitecaps appear where and when the geometry actually breaks, accumulate into a persistent world-space field, and streak behind the crest as they decay. **Colour and transparency are the same mechanism.** Per-channel Beer–Lambert extinction over the distance light travelled through water gives both — red dies within a metre, blue survives tens. That is why shallow water over sand reads turquoise and the open sea reads near-black blue without switching materials. **The seabed** is one noise field read twice: scaled it is the terrain's relief, unscaled it picks between sand and rock, so outcrops stand on the high ground and sand fills the hollows. The sun's caustic web moves over both, bent by the horizontal displacement of the water directly above it. Bodies land on it: the pass that raises the ground writes the same field out as a height patch that travels with the viewer, so what a body stands on is what the frame drew. Nothing here ships an image. Every map the surface and the seabed sample — the foam patterns, the sand, the rock, the caustics — is grown on the GPU at startup. ## The pieces | Asset | What it is | |---|---| | `components/Ocean` | Puts a sea on an entity. Its fields are the sea state; the simulation is rebuilt from them, so an ocean survives a scene reload. | | `modules/ocean` | The substrate: `attach`, `create`, `forEntity`, `sampleHeight`, `sampleDisplacement`. | | `components/Buoyancy` | Floats a rigid body on the sea. Its fields are the hull: how dense it is, how steady, and what box displaces water. | | `modules/buoyancy` | The forces: `attach`, `forEntity`, `columns`, `submergedFraction`, `restingY`. | | `modules/oceanPresets` | Nine named sea states, from `calmClear` through `gale`. | | `modules/oceanQuality` | The four tiers — how finely a sea is resolved, as distinct from what sea it is. | | `modules/oceanClipmap` | The camera-following ring geometry both the surface and the seabed are built on. | | `modules/oceanFloor` | The seabed: terrain, ground materials, caustics and the ground physics collides with. | | `modules/oceanScene` | The seam between the scene capture and the materials that sample it. | | `shaders/oceanSurface` | The water: cascade normals, absorption, exact dielectric Fresnel, subsurface scattering, sun glitter, foam, and the view from below. | | `shaders/oceanFloor` | The seabed: sand and rock blended by terrain noise, under a caustic web. | | `materials/oceanWater`, `materials/oceanSeabed` | The default looks. | | `renderFeatures/oceanScene` | Copies the frame's colour and depth so the surface can refract what is behind it and measure its own water column. | | `computeShaders/ocean_*` | The ten-stage GPU pipeline. | ## Wind is the control Significant wave height goes as the **square** of wind speed, so that one field does most of the work: | Wind | Sea | Wave height | |---|---|---| | 3 m/s | glassy, a mirror | ~0.2 m | | 11 m/s | working sea, occasional whitecap | ~2.5 m | | 24 m/s | gale, breaking and streaked | ~12 m | Everything else shapes character rather than size: `choppiness` pinches crests into peaks, `standingWaveRatio` runs waves both ways instead of only downwind, `jonswapGamma` sharpens a fetch-limited sea, and the foam layers decide how readily a breaking crest whitens and how long it streaks. Read `documentation/oceans.guide` for the full walkthrough, including the seabed, buoyancy, reflections and what each tier costs.

# Generator A live procedural generator: it binds a `.procGraph`, plays the graph's timeline and stands each of the graph's outputs in the scene as children of the entity it is on. Change a param and the output is made again in place; in edit and in play alike, nothing it makes is written to the world's source. ```lua local graph = asset.create("procGraph", "crate") -- a box with a `size` input; edit its init.luau local e = entity.spawn("crate") e.component.add("Generator", { graph = graph }) e.component.get("Generator").params = { size = 2 } ``` ## Fields | Field | What it does | |---|---| | `graph` | The `.procGraph` it plays. | | `params` | Overrides for the graph's declared inputs, by name. | | `output` | One declared output to stand; empty, the default, stands every output, one root each. | | `playOn` | `"auto"` (default) plays a timeline with no end as soon as it binds and holds any other on its first frame; `"load"` plays on bind; `"manual"` waits for `play()`. | | `ending` | `"graph"` (default) does what the timeline declares; `"loop"` plays the range round and round; `"hold"` plays it once and stays on its last frame. | | `speed` | How fast its clock runs: 1 its own rate, 0 still, negative plays a timeline with an end backwards. | | `diskCache` | Whether the outputs the graph caches load from, and are written to, the world's disk cache. On by default. | | `cookBudgetMs` | Milliseconds of cook work a frame before a cook yields to the next frame. 5 by default. | ## Methods `play()`, `pause()`, `seek(seconds)`, `seekFrame(frame)`, `loop()`, `hold()`, `setFps(fps)`, `setRange(first, last)` and `setWallTime(on)` drive its clock, on every peer. `getFrame()`, `getTime()`, `describeGraph()` and `playback()` read it; `playback()` also says what running the graph costs and how each output is drawn. `cancelCook()` stops a cook in flight and leaves the last output standing. `apply()` swaps the generator for the asset it makes: the frame being presented becomes a bundle, and an `Asset` component standing it takes the Generator's place. The `onFinished` event fires when a range played once reaches its end. A timeline that runs in real time (`realTime = true`) has an end when its graph states `frames` beside it (`g:timeline({ realTime = true, fps = 60, frames = 180 })`) or when `setRange` gives it one; with neither it runs on and never finishes. When the playhead of one with an end reaches its last frame, `ending` applies as it does to any timeline: `"graph"` loops where the graph declares `loop` and otherwise holds on the last frame and fires `onFinished` once; `"loop"` plays it again from the start, a fresh simulation each time, without firing it; `"hold"` stays on the last frame. `play()` plays a held one again from its start. `playback().ends` is whether the timeline has an end, and `last` is its last frame. A real-time timeline begins again, by `seek(0)`, a loop or `play()`, in the runs its solvers hold on the device: a restart costs a rewrite like any other present, and opens no cook. ## Under an effect An effect's play runs each graph of its entry on a Generator, a child of the play's entity. `effectRef:play(entry, opts)` and the `Effect` component make them and drive their clocks together, so a shot, an impact or a cast is a play of an effect (`guides { path = "topics/visual-effects" }`). The play's own `playback()` adds its Generators' costs together, and `procgen.frames` and `procgen.onPresent` take the play's entity as they take a Generator's. Every play of one graph with the same params plays the frames the first one cooked. A Generator of a graph with `playOn = "manual"` cooks every frame of the timeline while it waits, and `playback().cookedThrough` reaching `playback().last` says every frame is cooked. ## Related - `guides { path = "systems/procgen/documentation/procgen" }`: graphs, ops, timelines, effects and the live generator in full. - The `procgen` toolbox: `spawn`, `adjust`, `apply`, `generators`, `cooks`, `frames` and `onPresent` work on generators by entity.

# proc Code-authored, graph-backed procedural generation for the Zero engine. A graph is one function of `g`: `proc.define(function(g) ... end)`. Nodes are called by family and name (`g.<family>.<name>({ ... })`), inputs are declared with `g:input(name, default, opts)`, the returned table is the graph's outputs, and `io.output` is how the graph stands in the world. `builder.module/README.md` holds every rule of that form. This module owns the whole procedural model: the graph builder + data model, the operation registry, the type system, the lazy cached evaluator, deterministic scoped hashing, and the node-family op implementations. Authored `.procGraph` graphs are persisted via `procGraph.assetType`; the `procgen.preview` / `procgen.spawn` operations live in `procgen.toolbox` and are invoked as tools: `use_tool` from an agent, or `tools.use("procgen", "preview", args)` from a script. Generated meshes/materials/textures/bundles are persisted through their own `.assetType`. An op family can also come from outside this package: a `.procPack` asset registers its ops in the same registry, called as `g.op.<id>(...)` exactly like the ones shipped here (`proc.registerPack(name, ops)` is what it registers through, and what a test or a tool calls to hold a family for the life of one VM). `terrain.*` is one such pack, shipped in `terrainSystem.package/procPacks/` and covering a whole landscape; `guides { path = "systems/terrainSystem/documentation/terrain" }` is its guide. To find out what the registry holds, use the `procgen` toolbox: `searchNodes` searches it and `describeNode` describes one node or op. `proc.search_ops(query)` and `proc.schema(id)` are the same answers in-process, for a graph builder looking something up while it runs.

# Scatter Strews copies of one shape over the surface of another, each with its own turn, lean and size. Both the surface and the thing scattered are inputs, so this covers rocks on a hillside, crates on a deck, bushes along a bank or rubble across a floor: wire it a different `source` and it is a different field. It makes points on the surface (`points.on_surface`, area-weighted), gives every point its own random yaw, lean and scale (`instances.randomize_transform`), and places the source on those points (`instances.on_points`). The transform is read from the same point cloud the instances sit on, so each copy takes the pose of its own point. ## Inputs | Input | Type | Default | What it does | |-------|------|---------|--------------| | `surface` | Geometry | none | What the copies land on. Points are area-weighted, so a bigger face gets proportionally more. | | `source` | Geometry | none | The shape being copied. | | `count` | Int | 200 | How many copies. | | `seed` | Int | 1 | Changes the arrangement. The same seed always gives the same field. | | `scaleMin` | Float | 0.8 | Smallest per-copy size multiplier. | | `scaleMax` | Float | 1.4 | Largest per-copy size multiplier. Equal to `scaleMin` means uniform. | | `tilt` | Float | 0.15 | Radians of random lean off vertical. `0` stands every copy upright. | ## Output `instances`: a population, the points each carrying the source as its `Mesh`. A Generator draws it as one hardware-instanced draw call per source; `instances.realize` merges it into a single Geometry. ## Calling it Another graph calls a `.procGraph` as it calls a node, by its path or identity, naming the inputs in a table; the call answers what the graph outputs (`instances`). Its declared inputs are the call's inputs.

# json JSON encode/decode library for Luau. Encodes Lua values to JSON strings and decodes JSON strings back to Lua values. Used for communication with the Rust side of the engine, the VFS read/write bridge, and any wire-format that needs JSON. Pure Luau, no engine dependencies. Compact and pretty-printed encoders, plus a hand-rolled decoder that streams the input by position so it works under WASM as well as native. ## Exports - `Json.encode(value: any, indent?: string, currentIndent?: string) -> string` — compact encode. Functions / unknown types and NaN/Inf encode as `null`. - `Json.encodePretty(value: any, indentStr?: string) -> string` — pretty-printed encode with sorted object keys (diff-friendly). - `Json.encodeArgs(...: any) -> string` — encode varargs as a JSON array. - `Json.decode(str: string) -> any` — decode a JSON string. Returns the decoded value, or `nil` + error message on failure. ## Usage ```luau local Json = require("@builtin::modules.json") local widget = { type = "button", text = "Click Me" } local compact = Json.encode(widget) -- '{"text":"Click Me","type":"button"}' local pretty = Json.encodePretty(widget, " ") local decoded = Json.decode(compact) local v, err = Json.decode("oops") -- v = nil, err = error message ``` ## Notes - Object keys are sorted alphabetically in both encoders for consistent output across runs. - Numeric keys on objects are stringified at encode time (JSON has no numeric keys). Pure-integer key sets get detected as arrays via `isArray` and encoded with brackets. - NaN, +Inf, -Inf encode as `null` — JSON has no representation. Round trips through `decode` recover `null` (Lua `nil`), so they don't preserve. - Unicode `\uXXXX` escapes decode to UTF-8 by hand to stay WASM-safe. Only the BMP is covered; supplementary planes via surrogate pairs are not. - Functions encode as `null`. - Decode is character-streamed — no regex, no `string.match` patterns on the whole input — so the line-and-column information needs to be reconstructed from the position offset.

# prefab Entity prefabs and bundles: the records a spawned hierarchy is made of, and the asset they persist as. The definitions live in `proc.ops.prefabs`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "prefab" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. Each `prefab.*` op also answers to the same id with `template` in place of `prefab`. ## Ops - `prefab.empty` - `prefab.add_component` - `prefab.from_geometry` - `prefab.from_geometries` - `prefab.from_instances` - `prefab.from_population` - `prefab.from_asset` - `bundle.from_population` - `bundle.from_asset` - `bundle.from_prefab` - `bundle.from_instances` - `bundle.join` - `bundle.write` - `bundle.spawn` - `prefab.entity` - `prefab.parent` - `prefab.link` - `scene_fragment.write` - `part.merge` - `part.unpack`

# prefab (nodebox) Prefabs: the entity records a spawned hierarchy is made of, as record and list values. prefab.empty makes a root, prefab.entity, prefab.parent, prefab.add_component and prefab.link shape the hierarchy (each calls prefab.edit, which holds the record-list edits and the name lookup that prefab.find answers), and prefab.from_geometry, prefab.from_geometries, prefab.from_instances, prefab.from_population and prefab.from_asset make prefabs from what a graph built. The output node shows a prefab and the export node saves it as a bundle. prefab.record and prefab.find are the parts the others are built from: one entity record, and a lookup of an entity by name.

# component Components an element carries into the scene, their fields set from constants, animated values or other nodes' outputs. `procgen.searchNodes("", { pack = "component" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `component.set` — give every element of a class a component, native or script, with its fields given by name: a constant, an animated value, or a node's output wired in, such as the Material a `material.shader` node made.

# sweep Building a surface from a curve: sweeping a profile along it, revolving it, lofting between them. The definitions live in `proc.ops.sweep`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "sweep" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `geometry.sweep` - `geometry.revolve` - `geometry.loft`

# instances Placing copies of a source on points, varying them, and realizing, drawing or spawning the result. The definitions live in `proc.ops.instances`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "instances" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `instances.on_points` - `instances.randomize_transform` - `instances.pick_random` - `instances.pick_by_attribute` - `instances.realize` - `instances.spawn` - `instances.draw` - `instances.cull` - `instances.set_material` - `instances.transform` - `instances.from_bundle`

# emit Shapes particles are born from. Each op makes a point cloud, and each point carries `N`, the direction pointing out of its shape. Wire the cloud into `sim.spawn`: a particle is born on one of its points, and the source's `speed` launches it along that point's `N`. `procgen.searchNodes("", { pack = "emit" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `points.sphere` — points in a ball, or on its surface with `shell = 0`. `N` points straight out from the centre. - `points.cone` — points spread evenly across a cone's angle around an axis. With no `length`, every point sits at the apex: a nozzle whose `N`s fan out across the cone. A `length` fills the cone's volume out to that distance. - `points.cylinder` — points in a cylinder, or on its side with `shell = 0`. `N` points straight out from the axis. - `points.on_mesh` — points scattered evenly by area over a mesh's faces. Each point carries every attribute the mesh holds where it landed: - point and vertex values are blended across the face; - a face's own values come from that face; - values that cannot be blended come from the nearest corner. `N` is the mesh's normal there, or the face's own normal when the mesh carries none. Particles born on a painted mesh take its colour with them. ```lua local g = proc.graph("jet") g:node("nozzle", "points.cone", nil, { count = 256, direction = { x = 0, y = 1, z = 0 }, angle = 12 }) g:node("src", "sim.spawn", { points = "nozzle" }, { rate = 400, speed = { x = 4, y = 7 } }) g:node("sim", "sim.particles", { sources = { "src" } }) ```

# field.distance (procNode) How far each element's position is from a target, as a Float field. It makes the target the wired `b` field or, when `b` is left unwired, the fixed `point` as a constant field (`value.fallback`, `field.constant`), then measures with `field.vector_math` in `distance` mode from `a` to that target. The result compiles to the device with the rest of the field chain. ## Inputs - `a` (`Field<Vec3> | Vec3`): the positions being measured, one per element. - `b` (`Field<Vec3> | Vec3`): what each element is measured to, per element, so the target can move with the element. Wired, it stands in for `point`. - `point` (`Vec3`, default `{ 0, 0, 0 }`): one fixed position every element is measured to when `b` is unwired. It is how a radial falloff around a place is built. ## Outputs - `field`: the distance, a Float field.

# topology What a mesh is connected to: edges, boundaries, islands, adjacency, and conversion between element classes. The definitions live in `proc.ops.topology`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "topology" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `topology.edges` - `topology.boundary` - `topology.islands` - `topology.adjacency` - `topology.convert`

# strip Surfaces laid along curves. `geometry.ribbon` lays a flat ribbon of a width along every curve of a geometry, lying square to `up`. It is what a crack glowing in the ground, a trail, a beam, a tyre mark or a road is drawn with. Each edge of a ribbon carries every attribute of the curve point it was laid from, so a field or a material reads `generation`, `heat` or anything the curve carries across the ribbon. The mesh's uv is laid for a shader: - `uv.x` runs 0 to 1 along each curve, by distance; - `uv.y` runs 0 to 1 across it, so a hot core down the middle and a soft edge come from `uv.y` alone. Width can change along a ribbon: - `taper` narrows each ribbon toward its end, the way a crack thins to its tip; - `widthBy` names a Float point attribute that scales the width where the points carry it — for example a branch's width from its `generation` through a ramp, or a trail thinning with age. `lift` raises the ribbon off its curve along `up`, so one laid on a surface draws above it. `procgen.searchNodes("", { pack = "strip" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ```lua local g = proc.graph("fissure") g:node("line", "curve.line", nil, { start = { x = -1, y = 0, z = 0 }, finish = { x = 1, y = 0, z = 0 }, segments = 8 }) g:node("cracks", "curve.branch", { curve = "line" }, { generations = 3, branches = 2, normal = { x = 0, y = 1, z = 0 } }) g:node("glow", "geometry.ribbon", { curve = "cracks" }, { width = 0.05, taper = 0.9, lift = 0.004 }) g:output("glow", "glow") ```

# instances (nodebox) Instances: pack a geometry into a piece (instances.pack), place a piece set on target points (instances.to_points) and take a population or piece set apart (instances.unpack). A piece is one point whose `Mesh` holds a geometry whole; `geometry.merge` with `pack` puts several together into a piece set. The copies `instances.to_points` makes are a population, which the output node draws as instanced draws, one per piece and material, and export saves as a population asset; any other points stand as one entity each. instances.pack, instances.to_points and instances.unpack are the nodes of that chain, with `points.pose` composing the instance attributes (`P`, `orient`, `scale`, `N`, `v`, `up`, `pscale`, `rot`, `trans`, `pivot`) the copies stand at. Earlier nodes of the nodebox stand a source on points (instances.on_points), deal one of several sources to each point (instances.pick_random, instances.pick_by_attribute), vary and move the copies (instances.randomize_transform, instances.transform, instances.set_material) and merge them into one geometry (instances.realize). The points they make carry a `Mesh` and stand as entities through the output node. instances.place, instances.variants, instances.turn and instances.sources are the parts the others are built from: a transform written onto points, a variant index written onto points, the product of two rotations, and the geometries a population stands (the ones given, else the ones its points carry).

# scene Reading the scene into a graph. These nodes pull from the scene; every other node takes what they make as an input. A graph is evaluated in its own space, whose origin is the entity it stands on — a Generator's. An effect built at the origin therefore works wherever it is played, with nothing wired, and a pose brought in from the scene lands in that same space unless a node asks for the world's. ## Nodes - `scene.query` — entity ids out of the scene: by Name or a glob over Names, by a component they carry (native or script), as the children, descendants or parent of other entities, or the camera the scene is seen through. Its `of` and `within` take another query's ids, so queries compose. It outputs `ids` and their `count`. - `scene.fetch` — the entities `ids` names as points, one each, in that order. Every point carries its entity's id as `entity`; `transform` brings the pose as `P`, `orient` and `scale`, in the graph's space, the world's or each entity's own under its parent (`space`); `components` brings any component as an attribute named after it holding its record. Those are the attributes `proc.translate` writes back to an entity, so what a graph fetches, edits and outputs lands back on the same components. The pose follows the entities, and the graph's origin, as they move, without a cook. - `scene.input` — scene.fetch on the entity the graph stands on, always. Its pose in the graph's space is the origin; `space = "world"` says where the graph stands. A graph standing on no entity has no point here. - `scene.water`: the water the scene holds, read as it stands each frame: every surface a water system provides. Wired into `terrain.drape`'s `ground`, it sets points on the water, each taking the surface's height and normal and marked `wet`, and they follow the waves. `procgen.searchNodes("", { pulls = "scene" })` lists every node that pulls from the scene, these and the ones reading a particular part of it (`terrain.ground`, `sim.scene_colliders`).

# procgen The procedural-generation tool family: find the nodes a graph is built from, edit a graph's code, preview it, try values for its inputs, inspect it, spawn a live generator to iterate in the scene, and watch cooks as they run. A graph is the code of its `init.luau` (`proc.define(function(g) ... end)`); the tools here read that code, edit it, picture it and run it. ## Discovery - `searchNodes`: find nodes, the counterpart of `search_tools`: every node a graph calls (`g.<family>.<name>`, and the ops of packs as `g.op.<id>`), by keyword over names, families, inputs, outputs and descriptions and, in a session bound to a world, by meaning through ZeroMind. With no query it names every family and the nodes in it. - `describeNode`: one node in full, the counterpart of `describe_tool`: what it does, its inputs in call order with their types, defaults, ranges and options, its outputs, its family, the call a graph writes and what it costs. - `search` — free-text search over the `.procGraph` graph library (name / id / description / tag / category). - `find` — discover graphs by what they *produce* (an output type or producing-op substring, e.g. `{ produces = "Bundle" }`). - `inspect` — one node's op, sockets, producers, and consumers. - `coverage` — every current op with the new node that replaces it and its parity state, and every library graph with the worst state among the ops it names. - `stats` — structural counts (nodes / composites / inputs / outputs), plus evaluated-output stats when a `target` is given. - `trace` — the dependency chain for a target, in evaluation order. - `explain` — an agent-oriented natural-language summary of a graph. - `diff` — a structural diff between two graphs (changed/added/removed nodes, per-node deltas). - `validate` — type-check a graph: missing inputs, type mismatches, cycles, invalid composite bindings. - `generators` — survey every live procedural generator in the scene: bound graph, params, realized child count, and cook state. ## Edit the code These edit a graph's (or node's) `init.luau` as code and write it only once it builds, so the graph stays valid. A section is a run of statements named by the lines it spans; a call is named by the local it declares or a line it spans. - `collapse`: lift a section (a few node calls doing one job) into a node of its own: its inputs are the values the section reads, its outputs the values the code after it reads, and the section becomes one call of the new node. The graph cooks to the same result, and `searchNodes` finds the node. - `flatten`: the inverse: write a node's body out in place of a call to it (one call, every call of a node, or every call of a node outside the built-in library). - `reference`: put a call of an existing node in place of a section. - `promote`: make a part (a `.procGraph` called by its path) a node found by name, which stays the part's. - `patch`: set and unset what one call is given. - `modify`: structural edits as one change: add, remove and repoint calls, rename locals, declare inputs and outputs. ## Try it A tool that takes a graph to preview or run takes it by its VFS path or its name, or as a graph object (what `proc.define`, `proc.graph` and `proc.load` return); `spawn` takes a saved graph, since a generator plays an asset. - `tweak` — preview a graph with other values for its declared inputs, in a single step, leaving its source as it is: the knob-tuning loop. ## See it / make it real - `preview` — evaluate a target and render it for any output type (Geometry, points, Field heatmap, Material ball, Texture, Bundle); the picture comes back in the result beside its stats. - `spawn` — spawn a live procedural generator from a graph: creates an entity with a Generator component bound to it, realizing the output immediately and regenerating live as params change. - `adjust` — adjust a live generator in place: merge param overrides or switch the realized output. - `apply` — swap a live generator in place for the asset it makes: its current output becomes a durable bundle, and an Asset component standing it replaces the Generator, like applying a modifier. - `bake` — evaluate a target and realize it straight into the scene as durable content, without a live generator. ## Cook observability - `cooks` — the scene-wide cook monitor: every in-flight cook, a bounded history of recently finished ones, with progress (the nodes cooked so far and the node running now), status, duration, and — on failure — the error and the node that broke, and the frames generators presented most recently. - `cancel` — cancel an entity's in-flight cook; it stops at its next checkpoint and the previous output stays realized. - `onPresent` — be told the moment a generator presents the frame you describe (an output, a graph time or a time within a repeating cycle, an element count), with the probe's own options beside the terms: `capture` a picture of that frame (what the generator draws alone, framed to fit, over the grey studio backdrop), `freeze` the generator and the world on it (the generator plays on with `generator:play()`), a `when` and `run` of your own. It arms a probe, so `probe.list`, `probe.hits` and `probe.cancel` manage it. - `frames` — see how an effect goes: a picture of the frame a generator presents at each graph time you name (or `count` of them from `from` to `to`), each of what it draws alone, framed to fit, over the grey studio backdrop an asset preview is photographed in, with the frame, how it was presented and each output's element count beside it. A time past the end of a timeline shows its last frame, with a `note` saying so; a picture of a frame that draws nothing, or one that holds the backdrop alone, says so in its own `note`. A generator whose cook failed raises, naming the node and the reason. The clock goes back where it stood after.

# texture Textures generated from noise and gradients, and the PBR material that consumes them. The definitions live in `proc.ops.textures`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "texture" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `texture.noise` - `texture.gradient` - `texture.from_raster` - `texture.from_shader` - `material.pbr`

# part (nodebox) part.merge packs several values into one part, each piece keeping what it is; part.unpack gives one piece back by its name.

# curve Curves as geometry. A curve is a primitive of a Geometry: a run of its points, in order, open or closed, that is a line rather than a surface. A mesh built from the geometry draws its faces and not its curves. The curve's points are points like any other, so every point and field op moves them. One geometry holds any number of curves (the branches of a crack, the strands of a bolt), and the ops that sample, sweep or grow along lines read every one. The definitions live in `proc.ops.curves`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "curve" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `curve.line` — a straight curve from `start` to `finish`, in `segments` spans. - `curve.circle` — a closed circular curve in the XZ plane. - `curve.bezier` — a cubic Bézier curve from four control points. - `curve.from_points` — one curve through a geometry's points, in their order; the points keep every attribute they carry. - `curve.smooth` — every curve rounded into a Catmull-Rom spline through its own points. - `curve.resample` — every curve laid out again with points evenly spaced by arc length, a set number per curve or as many as a spacing fits. Move curves with `geometry.transform`, displace them with `geometry.set_position` and a field, and join them with `geometry.append`. `points.on_curve` samples points along them, and `geometry.sweep` carries a cross-section along each one.

# field Fields: a value per element, built from position, attributes, noise and maths, sampled where an op needs it. The definitions live in `proc.ops.field`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "field" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `field.constant` - `field.index` - `field.position` - `field.normal` - `field.attribute` - `field.random` - `field.noise` - `field.math` - `field.vector_math` - `field.compare` - `field.mix` - `field.map_range` - `field.distance` - `field.swizzle` - `field.combine`

# math One node per operator and function of the authoring surface: add, sub, mul, div, mod, pow, neg, abs, min, max, floor, ceil, sqrt, sin, cos, tan, acos, atan, log, sign, deg, rad, clamp, lerp, smoothstep, length, normalize, dot, cross, vec2, vec3, vec4, the comparisons (lt, le, gt, ge, eq, ne, and `compare` over them), `where`, the integer functions (to_int, to_float, bor, bxor, shl, floordiv), and `concat` for text. Operators and `math.*` over sockets resolve to these nodes. Each calls an operation of `proc.fieldc.operators`: over plain numbers and vectors it answers the plain result, over a Column or a Field it answers a Field (a fieldc template), so a chain of math nodes is one expression that the node consuming it evaluates in a single dispatch (`fieldc.evaluate`).

# entity Reading the live scene into a graph: an entity's transform, points, geometry and bounds. The definitions live in `proc.ops.entity`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "entity" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `entity.transform` — one entity's pose, as a value. - `entity.points` — a list of entities, or a parent's children, as ordered points: `scene.fetch` in the world's space or under each parent, with each entity's own `up` beside its pose. - `entity.geometry` — the mesh one entity's Model draws. - `entity.bounds` — one entity's bounds, or its hierarchy's. `scene.query` and `scene.fetch` (the `scene` pack) read any number of entities, with any of their components, in the graph's own space.

# ramp A ramp is a value that changes over 0..1. It is how an effect makes one thing follow another: colour over life, size over speed, opacity over height. `procgen.searchNodes("", { pack = "ramp" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `ramp.keys` — a ramp built from keys. Each key is `{ t, value }`, and the value can be a `Float`, `Color`, `Vec2`, `Vec3` or `Vec4`. Between keys the value moves in one of three ways: - `linear`: a straight line from key to key; - `smooth`: eased into and out of each key; - `constant`: each key's value held until the next key. - `ramp.blackbody` — the colours a blackbody glows at across a temperature range, as a Color ramp: red embers through orange flame to white. `glow` makes the hotter keys brighter; 4 follows the fourth power of temperature that real blackbody radiance does. - `ramp.sample` — a ramp read at every element, at the position along it a 0..1 field names. The ramp compiles to the element's dispatch, so a solver's particles read it on the device. - `field.ramp` — a ramp read at every element by a value it carries: a graph of `field.attribute`, `field.map_range` and `ramp.sample`. By default each element reads it by its own `life` attribute, so particles change over their lifetime. `by` names any other attribute, `range` maps that attribute's values onto 0..1, and wiring `t` reads the ramp by any field. A ramp is a graph value like any other. It can be wired, animated (its keys are params) and cached. ```lua g:node("fire", "ramp.blackbody", nil, { from = 900, to = 4000, glow = 1 }) g:node("tint", "field.ramp", { ramp = "fire" }) g:node("lit", "attribute.set", { domain = "sim", value = "tint" }, { name = "Cd" }) ```

# sink The sinks: a generated mesh, texture, material or population written out as a real asset. The definitions live in `proc.ops.sinks`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "sink" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `mesh.write` - `texture.write` - `material.write` - `population.write` - `debug.dump` - `debug.validate`

# core The parts the other procgen nodes are built from: connectivity (edges, boundary, adjacency, islands, owner, corners), normals, weld, select, stitch, curve measure and resample, sampling, neighbours, realize, the raster set (`raster.new`, `raster.read`, `raster.stencil`, `raster.sample`, `raster.add_layer`, `raster.remove_layer`, `raster.reduce`, `raster.column`, `raster.resolve`, `raster.blend`, and `raster.cells` under them), `column`, and `entity.read`, which brings scene entities in (assets come in through `io.import`). Each is a graph of the four ops, the kernels of `kernels/` and other core nodes. `join` holds the module that places the parts of a join, called by `concat` and `realize`. A graph calls them as `g.core.<name>`, for instance `g.core.edges`. A node with several outputs answers a record: `local faces = g.core.normals.face(...)` then `faces.geometry`, `faces.scaled`. Every node's README states its inputs and outputs.

# group Named selections over a mesh's points, vertices, edges or faces, for other ops to act on. The definitions live in `proc.ops.groups`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "group" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `group.create` - `group.by_normal` - `group.by_bounds` - `group.by_random` - `group.by_island` - `group.combine` - `group.invert` - `group.expand` - `group.shrink` - `group.list` - `group.info` - `group.remove`

# subdivide Catmull-Clark style subdivision: more faces where a surface needs to be smooth. The definitions live in `proc.ops.subdivide`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "subdivide" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `geometry.subdivide`

# asset The one node an asset enters a graph through. ## Ops - `asset` — an asset's content as a graph value, in the form its type states: a mesh is a Surface, a texture is a Texture. The asset is read when the node cooks. An asset type states the conversion in the `graph` its `behavior.luau` declares: `read(ref)` answers the value, and `write(value, name, place)` persists a value as that asset again. The sinks that write a value back (`mesh.write`, `texture.write`) go through the same `write`, so what enters a graph and what leaves it are one conversion. ```lua local rock = g:node("rock", "asset"):param("asset", "@builtin::meshes.sphere") local heights = g:node("heights", "asset"):param("asset", "terrain_height") ``` `procgen.searchNodes("", { pack = "asset" })` lists the family and `procgen.describeNode("op.asset")` describes it.

# Scatter (node) A scattering node: its `init.luau` holds the graph that does the work, so the declared inputs are this node's inputs and the declared output is this node's output. The node is its pipeline, in one self-contained asset. It makes points on the surface (`points.on_surface`, area-weighted), gives every point its own random yaw, lean and scale (`instances.randomize_transform`), and places the source on those points (`instances.on_points`). The transform is read from the same point cloud the instances sit on, so each copy takes the pose of its own point. A node is findable by what it does: the `procgen` toolbox's `ops` with the query `scatter` lists it beside `points.on_surface` and `instances.on_points`. Editing this node's `init.luau` cooks again every graph that calls it. ## Inputs - `surface` (Geometry): what the copies land on. - `source` (Geometry): the shape being copied. - `count` (Int, default 200): how many. - `seed` (Int, default 1): changes the arrangement. - `scaleMin` / `scaleMax` (Float, defaults 0.8 and 1.4): per-copy size range. - `tilt` (Float, default 0.15): radians of random lean. ## Output - `instances`: a population, the points each carrying the source as its `Mesh`. ## Authoring a node A node is a graph returned from a `.procNode`'s `init.luau` (`proc.define`). `asset.create("procNode", name)` scaffolds that shape, and `procNode.assetType/README.md` describes what a node states and how graphs call it.

# field.ramp (procNode) A ramp read at every element by a value it carries: a particle's colour, size or opacity following its age. It takes the value each element reads by (the wired `t`, else the element's own `by` attribute, through `value.fallback` and `field.attribute`), maps it from `range` onto 0..1 (`field.map_range`, the ends read off `range` by `value.get`), and reads the ramp there with `ramp.sample`, compiled into the element's dispatch. A value past either end of `range` reads that end of the ramp. ## Inputs - `ramp` (`Ramp`): the ramp to read. - `t` (`Field<Float> | Float`): where along the ramp each element reads. Unwired, it is the element's own `by` attribute. - `by` (`String`, default `"life"`): the Float attribute each element reads the ramp by when `t` is unwired. A particle solver's particles carry `life`, 0 at birth to 1 at death. - `range` (`Vec2`, default `{ 0, 1 }`): the values of `t` that land at 0 and at 1 on the ramp, so a speed from 0 to 20 or a temperature from 300 to 3000 reads the whole ramp. ## Outputs - `field`: the ramp's value at each element.

# decimate Reducing a mesh's triangle count while holding its silhouette. The definitions live in `proc.ops.decimate`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "decimate" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `geometry.decimate`

# bevel Rounding an edge or a corner into a chamfer of a chosen width and segment count. The definitions live in `proc.ops.bevel`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "bevel" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `geometry.bevel`

# geometry Composing and measuring meshes: transform, join, merge, triangulate, voxelize, delete, separate. The definitions live in `proc.ops.geometry`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "geometry" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `geometry.transform` - `geometry.append` - `geometry.recalculate_normals` - `geometry.triangulate` - `geometry.merge` - `geometry.measure` - `geometry.voxelize` - `geometry.set_material` - `geometry.set_position` - `geometry.delete` - `geometry.separate`

# editorSelection Named selection scopes for the editor. A scope is an independently tracked, ordered set of typed refs plus a primary (the last ref added or clicked). Distinct scopes never clobber each other, so viewport, outliner, inspector and asset browser share one answer to "what is selected" per kind. A ref is `{ kind: string, id: string }` — a stable id, never a display string, so rename/move never invalidates a selection. ## Exports - `M.scope(name) -> Scope` — get/create a named scope handle. - `M.set(scope, refs)` — replace refs in order; primary becomes the last. - `M.get(scope) -> { Ref }` — refs in click order (fresh array). - `M.primary(scope) -> Ref?` — last-clicked ref, or nil. - `M.clear(scope)` — empty a scope. - `M.toggle(scope, ref)` — add if absent, remove if present. - `M.add(scope, refs)` — add each ref not already present; primary becomes the last added. - `M.remove(scope, refs)` — remove each of `refs`; primary becomes the last remaining or nil. - `M.contains(scope, ref) -> boolean` — membership by `(kind, id)`. - `M.count(scope) -> number` — the scope's selection size. - `M.subscribe(scope, fn) -> handle` / `M.unsubscribe(scope, handle) -> boolean`. - `M.context() -> { scope, refs, primary }` — last-focused scope, for command ctx. ## Usage ```luau local Selection = require("@builtin::modules.api.editor.selection") local scope = Selection.scope("entity") Selection.set(scope, { { kind = "entity", id = "player_1" } }) Selection.subscribe(scope, function() refreshInspector() end) ``` ## Notes - State lives in a fixed `_G` slot, seeded pre-seal by the boot chain (`prelude.luau`); it survives hot-reload and edit↔play flips. Mutations after boot write into nested tables only. - `set` / `toggle` / `clear` mark their scope as last-focused, which drives `context()` and therefore which scope commands act on. - The service holds the editor's selection state in Luau. Refs handed back by `get` / `primary` / `context` are copies, so a caller can hold or mutate them without touching internal state.

# debug (nodebox) debug.dump summarizes any graph value into a record; debug.validate checks a Geometry's structure and reports every issue it finds.

# sim Simulation: what a solver's particles are born from, what pushes them and what they bounce off, and `sim.particles`, the particle solver. These are the sim context's nodes. What one of them makes is read by the solver at every step, so it is wired into another sim node or into an input that opens sim — `sim.particles`' `sources`, `forces` and `colliders`. Wired anywhere else, `procgen.validate` reports it and the cook refuses it. The definitions live in `proc.ops.sim`; this pack is what puts them in the node registry, so `procgen.searchNodes("", { pack = "sim" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Nodes - `sim.spawn` — a spawn description: particles born on a set of points at a rate and in bursts, with a starting velocity, a lifetime, a size and a stream name. - `sim.force` — a force the solver applies at every step, from any Vec3 field evaluated where each particle is: as an acceleration (`mode = "acceleration"`, scaled by `strength`), or as a velocity each particle is pulled toward at `strength` a second (`mode = "velocity"`). Wind is a wind field and drag is still air, both as velocities. - `sim.collider` — a plane, a sphere or a box the particles bounce off. - `sim.scene_colliders` — the scene's collision environment: every box, sphere and capsule physics collider that is not a sensor, turned and moving with its entity, solid from every side, and read where it stands in the graph's space at every step. Its `within` takes only the colliders near its `center`; a solver takes at most 128 shapes. Every shape is met along the whole of each step's move, so a fast particle does not pass through a thin one. - `sim.particles` — the particle solver, a geometry node: every particle from every spawn in one geometry on the GPU, stepped over the graph's timeline under the forces and against the colliders, output as the particles alive now. ```lua local g = proc.graph("sparks") g:node("emit", "points.sphere", nil, { radius = 0.1, count = 16 }) g:node("src", "sim.spawn", { points = "emit" }, { rate = 300, speed = { x = 3, y = 6 } }) g:node("curl", "field.curl", nil, { frequency = 0.8, amplitude = 4 }) g:node("swirl", "sim.force", { field = "curl" }) g:node("world", "sim.scene_colliders", nil, { bounce = 0.3 }) g:node("sim", "sim.particles", { sources = { "src" }, forces = { "swirl" }, colliders = { "world" } }, { gravity = { x = 0, y = -9.8, z = 0 } }) g:output("points", "sim") ```

# extrude Pushing faces out along their normals, and giving a surface thickness. The definitions live in `proc.ops.extrude`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "extrude" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `geometry.extrude` - `geometry.solidify`

# gpu Field ops evaluated on the GPU: one dispatch over a whole field, matching the CPU result. The definitions live in `proc.gpu`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "gpu" })` lists the family and `procgen.describeNode("op.<id>")` describes either of them. `proc.gpu.eval` is a convenience wrapper over the same registered ops. ## Ops - `gpu.scale` - `gpu.noise`

# shader An author's own compute shaders as graph nodes. A `.computeShader` written for anything else runs inside a graph unchanged: its bindings are the geometry's columns, its `params:` are the node's knobs, and what it writes comes out as columns every op after it reads. `procgen.searchNodes("", { pack = "shader" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `shader.compute` — run a `.computeShader` over a geometry's elements, one invocation per element. A buffer binding is the column of its own name, or the one `bind` names: `access: read` reads it, `access: read_write` writes it and makes it when the domain has none. The shader's `params:` take their values from `uniforms`, where each can be animated or wired, and `count`, `time` and `frame` are filled in when the shader declares them. The same shader placed as two nodes reads each node's own columns and values. - `sim.shader` — a solver whose step is a `.computeShader`: the domain's columns are its state, the shader runs once per element at every fixed step writing its `read_write` bindings in place, and `dt`, `time` and `frame` are the solver's own. ## Writing a shader for a graph The element index is `global_invocation_id.x`. A column's lanes are packed `f32`s: a Float column binds as `array<f32>`, a Vec3 column as `array<f32>` read three to an element, and a Vec2 or Vec4 column as `array<vec2<f32>>` / `array<vec4<f32>>`. ```yaml bindings: - { name: P, access: read_write, element: f32 } - { name: weight, access: read, element: f32 } params: - { name: lift, type: float, default: 1.0 } - { name: count, type: int, default: 0 } ``` ```wgsl @compute @workgroup_size(64) fn main(@builtin(global_invocation_id) id: vec3<u32>) { let i = id.x; if (i >= u32(params.count)) { return; } P[i * 3u + 1u] = P[i * 3u + 1u] + params.lift * weight[i]; } ``` ```lua g:node("raised", "shader.compute", { domain = "pts" }, { shader = "lift", uniforms = { lift = 2 } }) ``` ## Finding the points near a point A shader that looks at its neighbours — separation in a flock, the car ahead in traffic, a density — declares the three read bindings of a spatial grid and includes the `grid` shader module; the node gets a `neighborRadius`, builds a grid of the domain's points with cells that wide before it runs (and again at every step of a `sim.shader`), and binds it. The shader then walks the 27 cells around a point instead of every point. ```yaml bindings: - { name: P, access: read, element: f32 } - { name: nb, access: read_write, element: f32 } - { name: gcfg, access: read, element: f32 } - { name: grange, access: read, element: u32 } - { name: gorder, access: read, element: u32 } ``` ```wgsl #include "@builtin::systems.procgen.grid" let c = zero_grid_cell(p); for (var dz = -1; dz <= 1; dz = dz + 1) { for (var dy = -1; dy <= 1; dy = dy + 1) { for (var dx = -1; dx <= 1; dx = dx + 1) { let cc = c + vec3<i32>(dx, dy, dz); let span = zero_grid_range(cc); for (var s = span.x; s < span.y; s = s + 1u) { let j = gorder[s]; // j == i is the point itself; a j whose own cell is not cc // shares a bucket with it and belongs to another cell } } } } ``` ```lua g:node("flock", "sim.shader", { domain = "birds" }, { shader = "flock_step", neighborRadius = 1.5 }) ``` A step that reads its neighbours' state while every element writes its own would read some of them half-updated. A read binding named `prev_<column>` (`prev_P`, `prev_v`) is that column as it stood before the dispatch — a copy `sim.shader` takes before every step — so each element reads the same before-state and writes only its own: ```yaml bindings: - { name: P, access: read_write, element: f32 } - { name: prev_P, access: read, element: f32 } ``` `points.neighbors` answers the common questions — how many neighbours, the nearest, their centroid and their mean of an attribute — without a shader.

# grid A grid is space cut into cells: a geometry whose points are the centres of its cells, laid out x fastest, then y, then z, and whose point columns are its channels (a density, a distance, a height, a colour). A grid one cell thick along an axis is flat: the height over a ground, an image. Because a grid is a geometry, everything that works on points works on its cells. `attribute.set` writes a channel from any field, `attribute.accumulate` totals one, `attribute.promote` folds one into a single value. These ops add what knowing the layout gives: - `grid.box`: a grid of cells filling a box. Give it a cell count per axis, or a cell size. - `grid.cell_index`: which cell each position falls in (-1 outside), as a field. - `grid.neighbor_index`: the cell a fixed step away from each cell, held to the grid's edge, as a field. - `grid.sample`: a channel read at every point of a geometry, blended between the eight cell centres around it. `procgen.searchNodes("", { pack = "grid" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. Particles deposited into cells, then read back by the particles: ```lua local air = g:node("air", "grid.box", nil, { size = { x = 4, y = 3, z = 4 }, cells = { x = 32, y = 24, z = 32 } }) local cell = g:node("cell", "grid.cell_index", { grid = air }) local dense = g:node("dense", "attribute.scatter", { geometry = air, source = sparks, index = cell }, { name = "mass", as = "density" }) g:node("felt", "grid.sample", { geometry = sparks, grid = dense }, { name = "density" }) ``` A blur along x is two neighbours gathered and averaged: ```lua local right = g:node("right", "grid.neighbor_index", { grid = dense }, { offset = { x = 1, y = 0, z = 0 } }) local left = g:node("left", "grid.neighbor_index", { grid = dense }, { offset = { x = -1, y = 0, z = 0 } }) local a = g:node("a", "attribute.gather", { geometry = dense, index = right }, { name = "density", as = "r" }) local b = g:node("b", "attribute.gather", { geometry = a, index = left }, { name = "density", as = "l" }) ```

# geometry.recalculate_normals (procNode) Every vertex's normal averaged, by area, over the faces meeting it. The node is `geometry.smooth_normals` with a crease angle of 180 degrees and area weighting, so no vertex splits: a vertex shared by two faces is smooth across them, and one already split between two copies stays a hard edge. ## Inputs - `geometry` (`Geometry`): whose surface the normals are read off. Attributes and material carry to the result. ## Outputs - `geometry`: the geometry with recomputed per-vertex normals.

# data The operations a new node is built from. Each one is a single pass over a whole class of elements on the device. Processing data is a graph of these: a field computes a value per element, and these ops move it, fold it, and keep or reorder the elements. `procgen.searchNodes("", { pack = "data" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `attribute.gather` — each element reads a column from the element its index names, in this geometry or in a `source` geometry. Use it to read a neighbour or a parent, or to copy values across by id. - `attribute.scatter` — each element sends a column to the element its index names. Every receiving element folds what reached it (sum, mean, min or max), and an element nothing reached holds `fill`. Use it for deposits, per-cell totals and group sizes. - `attribute.promote` — moves a column between points, corners, faces and the whole geometry (`detail`). Moving to fewer elements folds; moving to more copies. - `attribute.accumulate` — a running or total fold of a column, over the whole class or within the groups that `by` names. - `elements.keep` — keeps the points or faces whose value is not 0, with every column they carry. - `elements.sort` — puts the points or faces in the order of a value. A threshold filter is `field.compare` into `elements.keep`: ```lua local tall = g:node("tall", "field.compare", { a = height, b = 2 }, { op = "gt" }) g:node("kept", "elements.keep", { geometry = pts, keep = tall }) ``` A total per group, standing on every member: ```lua g:node("islandArea", "attribute.accumulate", { geometry = mesh, by = island }, { name = "area", class = "primitive", mode = "total", as = "islandArea" }) ```

# material (nodebox) Materials as records: material.pbrMat is the standard metallic-roughness material made from its PBR maps (base colour, metallic-roughness, normal, occlusion, emissive) and their factors, and material.shader a material of any surface shader, holding every property and slot to what the shader declares. Each answers one element holding the record of the material kind (`records/material.procRecord`), which geometry.set_material, instances.set_material and the other inputs that take a material put on what draws; the output node shows it and the export node saves it as a `.material`.

# instances.cull (procNode) Keeps the instances a test says to. An instance survives when the value it is judged by is strictly above `threshold`; `invert` keeps the rest instead. The value is the `mask` field when it is wired, else the named point `attribute` (`field.attribute`). `elements.keep` on the points carries every attribute onto the instances that stay, so a culled set realizes as the whole one would have. With nothing to judge by, every instance stays, and inverted, none does. ## Inputs - `instances` (`Points`): the set to thin out, points carrying a Mesh. - `mask` (`Field`): the value each instance is judged by. Wired, it outranks `attribute`. - `threshold` (`Float`, default 0.5): an instance survives when its value reads strictly above this. Raising it thins the set, lowering it fills it back in. - `attribute` (`String`): a point attribute on the set to judge by, read while `mask` is unwired. A name the points do not carry is refused. - `invert` (`Bool`, default false): true keeps the complement, every instance the test dropped. ## Outputs - `instances`: the surviving instances.

# points.box (procNode) A 3D lattice of points filling a box centred on the origin. Each count is at least 1, and the extent the lattice spans is the counts times `spacing` (`value.math`). `grid.box` lays out the cells, x fastest, then y, then z, on the device, and each cell's centre is one point. `attribute.remove` takes the cell layout off the detail so the lattice reads as Points, and each point carries its own number as `id`. ## Inputs - `countX` (`Int`, default 3): how many points along X. The lattice holds countX x countY x countZ points and stays centred on the origin on every axis. Below 1 reads as 1. - `countY` (`Int`, default 3): how many points along Y, the layers the lattice is stacked in. 1 collapses it to a single flat sheet at y = 0. Below 1 reads as 1. - `countZ` (`Int`, default 3): how many points along Z. Below 1 reads as 1. - `spacing` (`Float`, default 1.0): distance between neighbouring points, the same on all three axes. The lattice spans (count - 1) x spacing per axis. ## Outputs - `points`: the lattice, with `id` numbering each point.

# material Materials made from any surface shader, with every property the shader declares set, animated or wired from the graph. `procgen.searchNodes("", { pack = "material" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `material.shader`: a material from a surface `.shader`. Each property its `properties.yaml` declares is set by name in `properties`, as a constant, an animated value or a wired output, and each texture slot by name in `textures`. `blend`, `cull` and `depthWrite` set how it draws. A shader that declares a `buffer` property reads, through `elements`, one vec4 per live element another part of the graph made. ```lua local ember = g:node("ember", "material.shader", { properties = { gain = 6 } }, { shader = "spark", blend = "additive", depthWrite = "false", cull = "none" }) ``` `material.pbr`, the metallic-roughness material, comes with the `texture` pack.

# abi The four ops every procgen node is built from. Each states where it runs in its `runs` field, and none calls another op. ## Ops | Op | Runs | Does | |---|---|---| | `device.kernel` | `gpu` | Runs a `.computeShader` over a domain of elements and returns what it wrote as columns | | `transfer.upload` | `cpu_to_gpu` | Turns CPU numbers, lists and tables into device columns | | `transfer.readback` | `gpu_to_cpu` | Turns device columns and live counts into CPU values, a frame or more later | | `cpu.call` | `cpu` | Calls a Luau function with declared return types and a time ceiling | ## device.kernel `kernel` (param) is the shader, a reference resolved from a literal where the node is written (`asset.resolve("<identity>", "computeShader")`; a name is refused); `specialize` (param) gives each of its `specialize` parameters one of its options. `bind` (input) gives every binding its value and `domain` (input) says how many elements run. - A buffer binding takes a Column. A binding the shader writes and that is bound to a Column writes a copy, and the copy comes back under the binding's name. - A `columns` binding takes a table of Columns, packed on the device into one buffer in the order the binding's `order` field states (`order: "shapeKind center extent"`; the table must hold exactly those columns), and in sorted-name order where the binding states none. A kernel that reads its columns by slot number states `order`; one that reads them by `NAME_col_<column>` needs none. - `specialize` takes the table `fieldc.walkSpec(step, opts).specialize` states as it stands (the walk kernel's `WALK_STEP`, `WALK_STEP_HI`, `WALK_DONE` and `WALK_PRELUDE`), and the resources the spec runs over come from `fieldc.bindSpec(spec)`: its `cols` (a table of columns already packed on the device) binds to the kernel's `columns` binding and its `u` (the numbers the chain carries, a device buffer) to its read `buffer` binding. The caller that made them lets them go (`bound.release()`) once the kernel's outputs are no longer read. - A Field bound to a binding is evaluated by the field compiler (`fieldc.evaluate`) in one fused dispatch over the domain, and the column it lands in stands as long as the outputs of the kernel do. - `bind.columns` is a domain (a record of Columns, or a class of a Geometry): every read binding the bind left unnamed takes the column of the same name, and an unbound `columns` binding takes every column of it. - An appended output bound to a column that an append returned writes a copy of it, and the copy keeps the live count that column carries, so a later pass appends after what an earlier one appended. - A param takes a Number or a Bool (1 or 0). A Vec spreads over `<param>_x` to `<param>_w`. `count`, `time` and `frame` are names any node may give; a kernel that declares none of them leaves them out. - A Texture binds its `texels` column, and sets `<name>_width` and `<name>_height` where the shader declares them. - `domain` is a Number, a Column (its elements), or a live count: a count Column, an appended output, or the record `{ count = <one-word Column>, capacity = <Number> }`. A live count dispatches over its capacity, and the shader reads the count through a `buffer` binding named `domain_count`. A shader that declares `domain_count` over a plain number gets the number in it. The live-count form is stated in "Over a live count" below. - An output with `count` or `capacity` is allocated before the dispatch. An appended output comes back as a Column (its `_capacity` and `_liveCount` set) and as `<name>_count`. Outputs: `columns` (Record of Columns) and `info` (the kernel, the variant key, the elements, the determinism the shader declares, the specialization). Column elements are 32-bit words: an `Int` column holds `i32`, a `UInt` column `u32`, every other type `f32` (`column:element()`). A kernel's `i32` and `u32` outputs are `Int` and `UInt` columns. The first run of a kernel waits for its program to be built, so a readback asked for after the run sees what the dispatch wrote. A column whose words are not the ones a binding reads is cast by value before the dispatch: a Float column meeting an `i32` or `u32` binding (and an Int or UInt column meeting an `f32` one) is read as the numbers it holds, not as the bits of its words. The cast covers read bindings and in-place bindings; what a kernel writes back through an in-place binding is the column of the binding's type (`Int` for `i32`). ## Over a live count A kernel runs over a plain number of elements (every slot live) or over a capacity whose live count sits in a one-word device buffer. A node that deletes, welds, expands or pairs elements states the count it made on the device, and the next kernel takes it as its domain, so the count never crosses to the CPU between them. **What a node passes.** `domain` is the count and the capacity it is bounded by: `found.indices.count` (the count of an appended output, whose capacity the output carries), an appended output Column itself, or the record `{ count = <one-word Column>, capacity = <Number> }` for any other count held on the device (a scan's `total`, a count made by `proc.device.count`; its words are read as u32). A Number is the plain form, as before. **What a kernel declares.** In `bindings.yaml`, a count binding that exists only in the variant that reads a count, and the specialization that picks the variant: ```yaml bindings: - { name: domain_count, kind: buffer, access: read, element: u32, when: "COUNT=device" } specialize: - { name: COUNT, options: [plain, device] } ``` `device.kernel` runs the `COUNT=device` variant when the domain is a live count, and the `plain` variant (the bindings and the code the kernel always had) when it is a Number. A kernel that declares `domain_count` without `when` reads it in every variant, and gets the number in it over a plain domain. **What the shader does.** The dispatch covers the capacity (`zero_n()`), outputs sized by `n` hold the capacity, and the live count is `min(domain_count_get(0u), zero_n())`. The code that reads it sits in `// @when COUNT device` ... `// @end` blocks (`compute_abi` removes a block from the variants it does not name). A slot at or past the live count reads nothing and writes the inert value of each output it owns: | Kernel | Inert value of a slot past the live count | |---|---| | `gather` | `dst` is zeros | | `compact` | `inverse` is -1; `indices` is -1 past the kept ones | | `scan` | `dst` is the total of the last group (0 for an empty run) | | `jump` (rank, min) | `parent_out` is the slot itself, `value_out` is 0 | | `loops` | stage clear writes every slot of the dispatch; stage link: `next` is the slot itself, `head` is 0 | | `loops_cut` | `head` is 0, `cut` is the slot itself | | `loops_place` | `ring` is -1, `pos` is 0 | | `edges_runs` | `flag` is 0; `a` and `b` are -1, `fcount` is 0 | | `expand` | `owner` and `local_index` are -1 past the sum of the counts | | `hash_gather` | `items` past the count are left as allocated (0) | **A new count.** A kernel that makes a count writes it to an appended output's counter, which the op returns as `<output>_count` and as the live count of the output (`output.count`); it carries its capacity and is a domain as it is. `compact` writes the kept count, `expand` the sum of the counts, `hash_gather` the number of points listed, and `scan` states its total in `total` (an `i32` scan's total is a count: `{ count = scanned.total, capacity = ... }`). **Capacity.** When the node does not know a count it allocates for the bound it can state, and the kernel never writes past it. `compact`, `gather`, `scan`, `jump`, `loops*` and `edges_runs` write at most as many slots as the capacity they run over. `expand` holds at most `n` slots (`n * k` when no count exceeds `k`). `hash_gather` holds at most its `total` param, which is the bound the node states (a pair list has no smaller bound than points times queries). In those two the count buffer states the true count whatever the capacity: a count above `.capacity` is an overflow, the first `capacity` slots are written and the count minus the capacity is how many did not fit. A node that states a bound checks `count <= capacity`. **Storage buffers.** A stage binds at most 8 on the web. A `COUNT=device` variant binds one more than the plain one, and the table counts the variants that exist: | Kernel | plain | device | |---|---|---| | `gather` | 3 | 4 | | `compact` | 4 | 5 | | `scan` | 4 | 5 | | `jump` | 7 | 8 | | `loops`, `loops_cut`, `loops_place` | 6 | 7 | | `edges_runs` | 8 | 5 (heads), 8 (table) | | `expand` | 5 | 6 | | `hash_gather` | 6 | 8 | `edges_runs` binds the buffers of its own stage in the device variant (`when: "COUNT=plain; COUNT=device STAGE=table"`), which is how it stays at 8. `abi.directLimit` counts every `buffer` binding the schema declares, `domain_count` included, so a kernel with a `columns` binding that adopts the form has one direct column fewer; none of these ten has one. ## transfer.upload `values` is a Record. A Number becomes a one-element Float column; a list of numbers a Float column; a list of `{x,y,z}` a Vec column, a list of text (or `{ type = "String", values = {...} }`) a column of the values; `{ type = "Int", values = {...} }` a typed column (`Float`, `Int`, `UInt`, `Vec2`, `Vec3`, `Vec4`, `Color`); a table of those a table of columns; a Column is held as the device run it has. ## transfer.readback `columns` is a Record of Columns, live counts, plain values (numbers, booleans and text answer themselves) or tables of them, a Field (evaluated over the elements of the column it reads, then read; a Field that reads no column has no length and is refused naming the form to use), or a Geometry or a Part, which answers the copy holding what its columns held. A live count answers a Number, a Float or Int column a list of numbers, a vector column a list of `{x,y,z,w}`. The op waits across frames; `report` states the names, elements, bytes and frames. Anything that waits on a readback value is a planning step. ## cpu.call `fn` (input) is called with `args` (input). `returns` (param) lists the type name of each result (`Number`, `String`, `Bool`, `Function`, `List`, `Column`, `BufferRef`, or a procgen type) and a call that returns anything else is refused. `ceilingMs` (param) refuses a call that took longer. A device Column reaches the function as a `BufferRef { buffer, type, count, lanes, element }`.

# component (nodebox) component.set gives every element of a class a component with the fields given.

# texture (nodebox) Textures: images drawn on the device as Texture values, a width, a height and one colour per texel. texture.noise and texture.gradient draw from a formula, texture.from_shader from an author's compute shader and texture.from_raster from the layers of a raster. A material takes a Texture in a slot, and the output node shows one. texture.cells is the part the first two are built from: one point per texel carrying its column and row.

# geometry Nodes that move, join, cut, round, thicken and sample meshes. A graph transforms a geometry (`geometry.transform`, `geometry.set_position`, `geometry.merge`), welds and shades it (`geometry.weld`, `geometry.smooth_normals`), models it (`geometry.extrude`, `geometry.solidify`, `geometry.bevel`, `geometry.subdivide`, `geometry.decimate`), builds surfaces from outlines (`geometry.sweep`, `geometry.revolve`, `geometry.loft`, `geometry.ribbon`) and reads it into volumes (`geometry.voxelize`, `geometry.to_sdf`). Each is built from the core nodes and the kernels of the library. ## Nodes - `geometry.transform`, `geometry.set_position`, `geometry.set_material`, `geometry.merge`, `geometry.triangulate`, `geometry.measure`: the basic edits and the measurement of a geometry. - `geometry.weld` (with `match = "position+normal"` it keeps hard edges), `geometry.smooth_normals`: merging points and shading normals. - `geometry.extrude`, `geometry.solidify`, `geometry.bevel`, `geometry.subdivide`, `geometry.decimate`: modelling. - `geometry.sweep`, `geometry.revolve`, `geometry.loft`, `geometry.ribbon`: surfaces from outlines and paths. - `geometry.voxelize`, `geometry.to_sdf`: a mesh as cells and as a distance field. - `geometry.boolean`: union, subtract or intersect of two closed meshes, over the `intersect` kernels. - `geometry.selected`, `geometry.flip`, `geometry.profile`, `geometry.tangents`, `geometry.sides`, `geometry.shared`, `geometry.bvh`, `geometry.rings`, `geometry.first`: the parts the nodes above are built from, each usable on its own. - `geometry.unit`, `geometry.perpendicular`, `geometry.rotate`, `geometry.transport`: vector arithmetic over sockets that the nodes which orient points and normals share. ## Conventions - Each node's folder name is its call name inside the box: `geometry.<folder>`. - Inputs and outputs carry the names of the op each node replaces. - A node that answers a Data table from numbers read back off the device holds the Luau for it in a `readings.module` inside its own folder. - A node with one output answers that output's value; a node with several answers a record by output name. - A fold's index runs from 1: the first pass is 1, so a pass that works on level, chunk or step `n` reads `index - 1` when it counts from 0 (`geometry.bvh`, `geometry.to_sdf`, `geometry.sweep`, `geometry.loft`). - A field bound to a kernel takes the length of that dispatch, so a node writes a value out as a column (a gather with an explicit `count`) before it binds one whose length differs from the dispatch's.

# edui.inspector.parts The building blocks a type's `inspector.luau` composes its sections from. Every Context carries this module as `ctx.parts`, so an inspector file requires nothing from `@builtin::editor`: ```luau return { sections = { { id = "summary", title = "Summary", build = function(ctx) local rows = ctx.parts.facts(ctx, { { label = "Vertices", value = 24 }, { label = "Size", value = ctx.parts.bytes(1536) }, }) local n = #rows for _, node in ipairs(ctx.parts.action(ctx, "rebuild", "Rebuild", function() ctx.ref:rebuild() end)) do n += 1 rows[n] = node end return rows end, } } } ``` Every function takes the section's Context first and returns a list of edui nodes, unless stated. | Part | What it shows | Callback key | |---|---|---| | `format(v)` | a value as text: integers plain, other numbers to 4 significant digits, booleans yes/no, a list as its length, a map as its entry count (returns a string) | — | | `bytes(n)` | a byte count as text: `84 B`, `1.5 KiB`, `2.00 MiB` (returns a string) | — | | `facts(ctx, rows, empty?)` | label/value rows (`{ label, value, mono? }`); the value takes the width its label leaves and wraps within it; a row whose value is nil shows "—", so a value that could not be read is seen to be missing. A row that does not apply to the subject is left out of `rows` by the section; with no rows `empty` shows | — | | `list(ctx, items, { max?, empty?, mono? })` | one text row per item, at most `max` (40), then "… and N more" | — | | `table(ctx, key, columns, rows, empty?)` | a table of records, each cell through `format` | `<keyPrefix>:tbl:<key>` (widget id) | | `links(ctx, refs, { max?, empty? })` | one button per asset (an AssetRef, a `{ __ref = guid }` envelope, or a guid or name), named and typed; clicking selects it. An item that does not resolve is listed as text | `<keyPrefix>:link:<guid>` | | `entityLinks(ctx, ids, { max?, empty? })` | one button per entity, by name; clicking selects it. An id whose entity no longer exists is listed as text, marked despawned | `<keyPrefix>:ent:<id>` | | `action(ctx, id, label, run, { primary? })` | a button running `run`; a run that raises shows its message beneath the button until the next run | `<keyPrefix>:act:<id>` | | `openFile(ctx, path, label?)` | an action opening `path` in the Code panel; nothing when the file is absent | `<keyPrefix>:act:open:<path>`, the path relative to the subject's folder | | `problems(ctx, problems, clean?)` | one notice per `{ message, code?, severity?, line? }` (error tone, or info for a warning, info or hint), or `clean` ("No problems.") | — | | `swatch(ctx, color, label)` | a colour square (`{ r, g, b }` in 0..1) beside its label and hex (returns one node) | — | | `cached(key, paths, compute)` | `compute()`'s value, computed again only when the content version of one of `paths` moves (returns the value). Read through `ctx.parts`, it is held while a Context that read it stays open; read through the module itself, until the next `Inspector.release` | — | | `state(ctx)` | the table a Context's sections keep state in between builds (a picked zoom, a chosen tab), forgotten when the Context is released (returns the table) | — | | `check(ctx, path)` | a "Check" action running `lsp.check(path)`, then the counts and diagnostics of the last check of the file's current content | `<keyPrefix>:act:check:<path>`, the path relative to the subject's folder | | `values(ctx, { subject, schema?, values?, write?, readOnly? })` | typed controls over any values: one control per schema field, each edit checked with `Field.check` and written through `write` inside one undoable operation; `readOnly` shows the values with no control that writes. The same subject shown by two Contexts keeps two states | `<keyPrefix>:val:<subject>:set:<field>` | ## Rules a section keeps - **No write in `build`.** A build only reads; writes happen in an action's `run`, in `ctx.setSettings`, or in a `values` part's `write`. - **Expensive reads are once per content version.** A build that decodes a payload, walks a file or asks the LSP goes through `cached` (keyed on the files the value comes from) or runs behind an action. `check` holds each file's last result for as long as the file's content is unchanged. - **Every callback key starts with `ctx.keyPrefix`**, so two subjects — the panel's asset and an inline editor of the same asset — never share one. - **What the parts hold goes with the Context.** `ctx.parts` is the parts as that Context reads them. `Inspector.release(keyPrefix)` forgets the Context's action failures, file checks and state, and every cached value no other open Context read.

# normals Welding coincident points and smoothing the normals that shading reads. The definitions live in `proc.ops.normals`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "normals" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `geometry.weld` - `geometry.smooth_normals`

# points Point clouds: grids, discs, poisson sets, points on a surface or a curve, and the ops that filter, relax and look around them. The definitions live in `proc.ops.points`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "points" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `points.grid` - `points.disc` - `points.poisson` - `points.box` - `points.on_surface` - `points.from_vertices` - `points.filter` - `points.on_curve` - `points.relax` - `points.neighbors` - `points.count_neighbors`

# sdf (nodebox) Signed distance field nodes: shapes, smooth combines, round and shell, space warps (transform, twist, bend, taper, elongate, mirror, repeat), displacement, grids and fields in and out, and sdf.mesh, which contours a shape into a closed mesh.

# points.grid (procNode) A flat lattice of points in the XZ plane, centred on the origin. Each count is at least 1, and the extent the lattice spans is the counts times `spacing` (`value.math`). `grid.box`, one cell thick at height `y`, lays out the cells, x fastest, then z, on the device, and each cell's centre is one point. `attribute.remove` takes the cell layout off the detail so the lattice reads as Points, and each point carries its own number as `id`. ## Inputs - `countX` (`Int`, default 4): how many points along X. The grid holds countX x countZ points and stays centred on the origin, so each one added widens it by `spacing`, half of that to either side. Below 1 reads as 1. - `countZ` (`Int`, default 4): how many points along Z. A count of 1 leaves a single row running along X. Below 1 reads as 1. - `spacing` (`Float`, default 1.0): distance between neighbouring points, the same on both axes. The grid spans (countX - 1) x spacing by (countZ - 1) x spacing. - `y` (`Float`, default 0.0): the height the whole lattice sits at. Every point takes this as its y. ## Outputs - `points`: the lattice, with `id` numbering each point.

# growth Curves that grow from other curves. The result is a single geometry holding every curve, starting curves included. Each point carries: - `generation`: 0 on the starting curves, one more per fork; - `u`: how far along its own curve, 0 to 1. Because the result is geometry, every curve, point and field op works on it: - roughen it with `geometry.set_position` and a noise field; - sweep it into tubes with `geometry.sweep`; - sample it with `points.on_curve`, for sparks along a crack; - read `generation` through a ramp, so branches thin as they fork. `procgen.searchNodes("", { pack = "growth" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `curve.branch` — branches sprout from each curve, generation after generation. Each curve sends out `branches` children from along its length. A child turns off its parent by up to `angle`, is `ratio` as long, and wanders as it goes. A `normal` keeps the growth in one plane, the way a crack keeps to the surface it crosses. Use it for cracks, lightning forks, frost and coral. - `curve.grow` — branches reach toward a cloud of attractor points (space colonisation). A node grows a step toward the attractors that pull on it, and an attractor a branch reaches is spent, so the growth fills the cloud's shape. Use it for canopies, root balls and leaf veins. ```lua g:node("impact", "curve.line", nil, { start = { x = -1, y = 0, z = 0 }, finish = { x = 1, y = 0, z = 0 }, segments = 8 }) g:node("cracks", "curve.branch", { curve = "impact" }, { generations = 4, branches = 2, angle = 45, wander = 25, normal = { x = 0, y = 1, z = 0 } }) g:node("here", "field.position") g:node("jag", "field.curl", { position = "here" }, { frequency = 3, amplitude = 0.05 }) g:node("rough", "geometry.set_position", { geometry = "cracks", offset = "jag" }) ```

# points.filter (procNode) Keeps the points a test says to. The value each point is tested by is the `mask` field when it is wired, else the named `attribute`'s values (`attribute.labels`). The test is a comparison (`field.compare`): above `threshold`, or, when `equals` is given, equal to the index that value or label names. `elements.keep` on the points carries every attribute and the detail onto the points that stay, counted on the device. Given neither a mask nor an attribute, the points come back as they are. ## Inputs - `points` (`Geometry`): the cloud to thin. Every point attribute and every detail value is carried onto the survivors, so a colour or an index still belongs to the point it started on. - `mask` (`Field`): the per-point value tested; a point stays when it is above `threshold`. Wired, it decides, and `attribute` is read only when this is empty. - `threshold` (`Float`, default 0.5): a point stays when its value is strictly above this. Raising it keeps fewer points. - `attribute` (`String`): a point attribute to test instead of wiring `mask`. A name the points do not carry is refused, naming the ones they do. - `equals` (`String | Float`): keeps the points whose `attribute` equals this instead of testing it against `threshold`. It is a number, or a label: one of the texts a text attribute holds, or one of the names the points' detail `labels` gives a numeric one (how one solver's particles are split back by the `stream` their source named). ## Outputs - `points`: the points that stay.

# boolean Union, intersection and difference between two solids. The definitions live in `proc.ops.boolean`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "boolean" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `geometry.boolean`

# geometry.delete (procNode) Deletes the triangles a test selects. A triangle is selected when its value is strictly above `threshold`. The value each triangle is tested by is the `mask` field when it is wired, else the named primitive `attribute` (`field.attribute`), else 0. `invert` deletes the triangles the test did not select. `elements.keep` on the primitives does the removal: every point stays, and the triangles that remain keep their corners and attributes, counted on the device. ## Inputs - `geometry` (`Curves | Surface`): whose triangles are thinned. Point and detail attributes carry over as they are; primitive and vertex attributes stay with the triangles that survive. - `mask` (`Field`): read once per triangle for whether it goes. Wired, it is what the selection reads, and `attribute` is read only when this is empty. - `threshold` (`Float`, default 0.5): a triangle is selected when its value is strictly above this. Raising it deletes less. - `attribute` (`String`): a primitive attribute on the geometry to read the selection from, instead of a wired mask. A name the triangles do not carry is refused. - `invert` (`Bool`, default false): true deletes every triangle the test did not select, so a mask naming what to keep cuts away the rest. ## Outputs - `geometry`: the geometry with the selected triangles removed.

# shader (nodebox) An author's own compute shaders as nodes. shader.compute runs a .computeShader over the elements of a geometry through the device.kernel op: each buffer binding is a column of the geometry, each param a knob of the node, and what the shader writes comes out as columns.

# flow Fields that push things around, and the noise they are made of. Each is a field like any other: `sim.force` applies it to a solver's particles, `attribute.set` writes it onto a geometry, and a field op combines it with others. Each also compiles to the dispatch its CPU form computes, on the same lattice hash as `field.noise`, so a solver evaluates it on the device at every step. A `position` left unwired is where each element of the domain stands: the particles a solver steps, or the points an `attribute.set` writes. Wire a position to sample the field somewhere else. `procgen.searchNodes("", { pack = "flow" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Fields that push - `field.curl` — curl noise. It swirls with no sources or sinks, so what follows it eddies without bunching up or thinning out. This is how smoke, dust and sparks move in turbulent air. - `field.vortex` — turning around an axis through a centre. It is strongest at the axis and falls to half at `radius`. - `field.attractor` — pulls toward a centre, fading to zero at `radius` when one is given. A negative strength repels. ## Orientation - `field.align` — the rotation turning an element's `axis` (+Y unless given) onto a direction, as the quaternion `orient` takes. An unwired direction is each element's own `v`, so written onto particles as `orient` it turns each one onto its motion. A card drawn with `zero_billboard_streak` then streaks along it. ## Noise - `field.worley` — the distance to the nearest scattered feature point. Use it for cells, cracks, scales and stone. - `field.simplex` — smooth signed noise in [-1, 1]. ```lua local g = proc.graph("embers") g:node("emit", "points.grid", nil, { countX = 1, countZ = 1 }) g:node("src", "sim.spawn", { points = "emit" }, { rate = 200, lifetime = { x = 2, y = 4 } }) g:node("curl", "field.curl", nil, { frequency = 0.6, amplitude = 5 }) g:node("swirl", "sim.force", { field = "curl" }) -- Air rising at 2 m/s: each ember is pulled toward that velocity, which is -- wind and drag in one. g:node("updraft", "field.constant", nil, { value = { x = 0, y = 2, z = 0 } }) g:node("air", "sim.force", { field = "updraft" }, { mode = "velocity", strength = 0.4 }) g:node("sim", "sim.particles", { sources = { "src" }, forces = { "swirl", "air" } }) ```

# scene (nodebox) scene.query finds entity ids by name, component and hierarchy, scene.fetch brings entities in as points carrying their pose and components, scene.input is the entity the graph stands on, and scene.water is the water the scene holds.

# geometry.separate (procNode) Splits a geometry's triangles in two by a test. The value each triangle is tested by is the `mask` field when it is wired, else the named primitive `attribute` (`field.attribute`), else 0. Two comparisons against `threshold` follow (`field.compare`): strictly above, and at or below. `elements.keep` on the primitives runs once for each, so `a` holds the triangles above and `b` the rest. Both keep every point, and between them they hold every triangle once. ## Inputs - `geometry` (`Curves | Surface`): whose triangles are divided. Point and detail attributes carry to both halves as they are; primitive and vertex attributes stay with each half's own triangles. - `mask` (`Field`): read once per triangle for which half it joins. Wired, it is what the split reads, and `attribute` is read only when this is empty. - `threshold` (`Float`, default 0.5): a triangle goes to `a` when its value is strictly above this, and to `b` otherwise. - `attribute` (`String`): a primitive attribute on the geometry to read the split from, instead of a wired mask. A name the triangles do not carry is refused. ## Outputs - `a`: the triangles whose value is strictly above `threshold`. - `b`: the rest. A call answers both as a record by output name.

# attribute Reading, writing and moving the per-element columns a mesh carries. The definitions live in `proc.ops.attribute`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "attribute" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `attribute.set` - `attribute.labels` - `attribute.remove` - `attribute.transfer` - `attribute.statistics` - `attribute.normalize`

# sdf Signed distance fields: shapes as distance, combined smoothly, and carried across to and from geometry. The definitions live in `proc.ops.sdf`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "sdf" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `sdf.sphere` - `sdf.box` - `sdf.rounded_box` - `sdf.torus` - `sdf.capsule` - `sdf.cylinder` - `sdf.cone` - `sdf.plane` - `sdf.union` - `sdf.subtract` - `sdf.intersect` - `sdf.transform` - `sdf.twist` - `sdf.bend` - `sdf.taper` - `sdf.elongate` - `sdf.round` - `sdf.shell` - `sdf.mirror` - `sdf.repeat` - `sdf.position` - `sdf.displace` - `sdf.mesh` - `geometry.to_sdf` - `sdf.from_grid` - `sdf.sample`

# sim (nodebox) Simulation nodes: sim.spawn, sim.force, sim.collider, sim.scene_colliders, sim.particles and sim.shader, built on the runtime's g:state and g:step.

# abiBox A node for the procgenAbi suite: it is called through the builder and written out in a graph.

# mesh The primitive solids and sheets a graph starts from: `mesh.box`, `mesh.sphere`, `mesh.cylinder`, `mesh.cone`, `mesh.capsule`, `mesh.octahedron`, `mesh.torus`, `mesh.rounded_box`, `mesh.plane` and `mesh.grid`. Each is made on the device from lattices and fans of the `make` kernel, with positions, normals and texture coordinates written as formulas over the lattice, and answers triangles centred on the origin that fill the box its parameters name. ## Conventions - Each node's folder name is its call name inside the box: `mesh.<folder>`. - Parameters keep the names and defaults of the op each node replaces. - `mesh.lattice` makes the lattices and fans the presets share, `mesh.spherical` the point of a sphere and `mesh.cube_faces` the faces of a cube; a preset writes its positions, normals and texture coordinates as formulas over the lattice.

# io The ways in and out of a graph: `luau` runs a function of a Luau module on the CPU, `output` shows a value in the world and answers a Handle, `export` saves a value as an asset, and `engine` calls the engine bridge the core reading nodes and `export` use. `output` holds `show.module` and `engine` holds `engine.module`, the functions they call.

# value Single values a graph computes with. A measurement turns into something a loop stops on, a count another node takes, or anything a switch decides. `procgen.searchNodes("", { pack = "value" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `value.get` — one field of a Data or record value, by a dotted path such as `bounds.max.y`. When the path misses, the error names the fields that are there. - `value.math` — `a <op> b` for add, sub, mul, div, min, max or pow. `b` is a wire or the `constant` param. - `value.expr` — a number that follows an expression over the graph's time (`t`, `frame`, the math functions) and the names `variables` gives it, each a constant, a graph input or another node's number. A curve that depends on graph inputs is this one node: `{ variables = { peak = peak, decay = decay } }` with `expression = "peak * max(0, 1 - t / decay) ^ 2"`. - `value.compare` — `a <op> b` for less, less_equal, greater, greater_equal, equal or not_equal, answering a Bool. - `value.switch`: `ifTrue` when `when` is true, `ifFalse` otherwise. Only the one taken is cooked. - `value.present`: whether anything is wired into `value`, as a Bool: what a graph used as a node asks of an input its caller may leave unwired. - `value.fallback`: the value wired into `value`, or `fallback` when nothing is. `fallback` is cooked only when it is the one taken. ```lua local stats = g:node("stats", "geometry.measure", { geometry = grown }) local top = g:node("top", "value.get", { data = stats }, { path = "bounds.max.y" }) local done = g:node("done", "value.compare", { a = top }, { op = "greater_equal", constant = 3 }) ```

# mesh The primitive solids a graph starts from. A `.mesh` asset enters a graph through the `asset` node (`procPacks/asset.procPack`), as the Surface the mesh type states. The definitions live in `proc.ops.sources`; this pack is what puts them in the op registry, so `procgen.searchNodes("", { pack = "mesh" })` lists the family and `procgen.describeNode("op.<id>")` describes any one of them. ## Ops - `mesh.box` - `mesh.sphere` - `mesh.cylinder` - `mesh.cone` - `mesh.plane` - `mesh.capsule` - `mesh.octahedron` - `mesh.torus` - `mesh.rounded_box` - `mesh.grid`

# entity (nodebox) entity.transform and entity.bounds read one entity's pose and bounds as values, entity.points reads a set of entities as points, and entity.geometry reads the mesh an entity's Model draws as a Geometry.

# io.output (procNode) Show a value in the world through the translation layer: a Geometry as a mesh, points that carry components (a Mesh, a Material, a light) as one entity each, the copies `instances.to_points` made as instanced draws, primitives as entities, a Texture, Material, Raster or Part as what each is. Answers a Handle that the runtime releases when the output goes away. Built from the Luau node (`io.luau`) over `show.module`, which sits in this node's folder: its `show` function registers what the value needs and answers the Handle. A graph is pulled from its output nodes. ```luau g.io.output({ value = mesh }) g.io.output({ value = rocks, class = "point" }) ``` ## Inputs - `value` (Value). The value to show: Geometry, Points, Part, Texture, Material, Field, Raster or Prefab. A Prefab stands as the entities its records describe. - `class` (one of "", point, primitive). Default `""`. What one element of a Geometry stands for in the world. Empty shows a geometry with primitives whole as one mesh and stands each point of a set of points that carries components as an entity; "point" or "primitive" stands each element of that class as its own. - `layer` (String). Default `""`. For a Raster, the layer drawn; empty draws `height` when the raster has it, else its first layer. - `name` (String). Default `"output"`. The base name of the entities and assets the show makes. ## Outputs - `handle`: the Handle of what was registered.

# islandLagoon The island the `island_lagoon` demo scene stands in, as a terrain graph. A flat lagoon bed at -14 m with a broad dome rising through sea level at roughly 1:21, carrying two surfaces: sand from the lagoon floor up past the waterline, grass over the dry crown. The gentle slope is the point — it puts a continuous range of water depth in front of the camera, which is what makes the ocean's shoaling, absorption and shoreline wash readable in one shot. ## Inputs None. Every dimension is authored in the graph; edit `init.luau` to move the waterline, widen the beach or change the relief. ## Outputs - `land`: the landscape as one element carrying `Terrain`, which the graph shows through `io.output`: the ground, its colliders and its water, standing in the scene. ## Consumers - `@builtin::systems.oceans.demo.island_lagoon` instantiates it as the demo's terrain and binds the ocean's `ground` to the entity it produces.

# assetType runtime The machinery that reads a `<typename>.assetType/behavior.luau` and turns its declarations into live behaviour. A `behavior.luau` is a table of declarations — `ref` methods, `modules` shared code, an `events` schema, a `namePattern`, `refShapes`, and the `onCreate` / `onRegister` / `onChange` / `onDelete` / `validate` / `settingsDefaults` / `settingsCorrections` hooks. None of it runs itself. This is the code that runs it, and it lives here because reading a type's declarations is the **assetType type's own behaviour** — the same way `material.assetType` owns what a `.material` does. ## Sub-modules | Module | Reads | Responsibility | |---|---|---| | `ref.module` | `ref`, `modules` | Builds every `AssetRef` envelope, attaches the shared metatable, and dispatches per-type methods and shared modules onto it. Also owns edit-mode write-behind persistence. | | `create.module` | `onCreate`, `namePattern`, `validate` | Backs `asset.create`: resolves the type, checks the name against its pattern, runs `onCreate` (or clones `template/`), and writes the instance. `validate.module` beside it checks a creation `opts` table against the type's `createSchema`. Before running `onCreate`, resolves the type's settings chain (below) and hands the result to the hook as `opts.settings`. | | `settings.module` | `settings`, `settingsDefaults`, `settingsCorrections` | A type's declared settings schema and where its values live (`type.yaml`'s `settings:` block). `Settings.resolveForCreate` layers the schema's own defaults, the type's own `settingsDefaults(name, opts, asked)` hook (a DEFAULT the schema can't express — a name-derived convention, a fact read off a payload the caller handed it, a value following a field `asked` shows a higher layer naming; any later layer overrides it), the Preset Manager, an importer's settings, the caller's `settings` table, then the type's own `settingsCorrections(values, name, opts)` hook (a CROSS-FIELD CONSTRAINT the schema can't express, applied last over the fully merged values). A correction over a default/preset/importer value lands silently; a correction that would override what the caller's own `settings` table explicitly asked for refuses the creation instead, naming the field and why. Neither hook is ever handed a table to mutate; each returns what it wants changed (`settingsCorrections` may also return a `{ [field]: reason }` table for that refusal message). `Settings.cloneValues` deep-copies a values table — `create.module` hands `onCreate` a copy, never the table it stamps. `Settings.valuesOf` / `writeValues` read and write an asset's own values file. | | `typeYaml.module` | `type.yaml` | The folder a type lives in and its parsed `type.yaml`, decoded once per content version of the file. `settings.module` and `inspector.module` read their blocks through it. `about` / `aboutAt` read a type's `about.yaml` (`intent`, `function`, `usage`), leaving out any key that is empty or still starts with `[[describe]]`; `aboutRows` and `aboutMarkdown` lay the texts out for the Inspector and the `types/<name>` guide. | | `inspector.module` | `type.yaml`'s `inspector:` block | Which inspector a type declares for its assets (`inspector: { type: ... }` or `{ instance: ... }`), and the declaration that file returns — the sections it adds, the generic ones it replaces, and their order — or the problem that kept it from loading. | | `onRegister.module` | `onRegister` | Fires an instance's once-only registration hook — on arrival, on world load, and for `@builtin` library instances. | | `changeDispatch.module` | `onChange`, `onDelete`, `refShapes` | Routes a VFS source write or a folder delete to the enclosing typed asset's type hooks. | | `refShapes.module` | `refShapes`, `ref` | Publishes what every `AssetRef<category>` answers to, so a member read on an asset-typed value is checked against that category's real surface. | | `events.module` | `events` | The per-asset event runtime behind `ref.events`. | | `instantiable.module` | `ref.instantiate` | The instantiation contract an asset type opts into: `root` stands the root entity, `place` applies the base placement opts to one the type adopted, and `result` shapes the `(root, idMap)` every `instantiate` returns. Also registers the `sceneInstantiable` field-constraint validator. | | `declaration.module` | `type.yaml` | The type's decoded declaration, read once and held until a write inside an `.assetType` folder; what every question about a type as a whole reads. | | `previewRecipe.module` | `type.yaml` `preview:` | How an instance's `preview.png` is produced: which of the four recipes (`instantiate`, `image`, `surface`, `custom`) the type declares, and what that recipe needs. | ## Reaching it ```luau local rt = require("@builtin::assetTypes.assetType.shared") rt.ref.loadTypeBehavior("material") ``` Fields resolve lazily. The prelude requires the sub-modules directly, in dependency order (`ref`, then `changeDispatch`, `onRegister.install()`, `refShapes.install()`) — a table that required all six on load would take that ordering away from it.

# Module (asset type) A module is a reusable, stateless (or globally-stateful) Luau library that other code pulls in with `require()`. Modules are the unit of factored-out logic in a world: helpers, math libraries, format parsers, registries, shared algorithms. ## When to use one - You have logic you want to share across multiple components, services, scenes, or tools. - You have a registry, lookup table, or shared cache that callers all read from / write to. - You want a stable API surface (`M.fn`) other code can depend on. If the logic is bound to one entity, use a `.component`. If you want a named UI of fields rather than functions, use a `.preset`. ## Where it lives - Source: `/zero/source/.../<name>.module/` - Identity: the source path with `/` written as `.` and each segment's type suffix dropped — `/zero/source/demo/beats.module` is `demo.beats`, and `/zero/source/kit.package/beats.module` is `kit.beats`, the container's name kept and its `.package` suffix gone. `asset.create` returns this string, `asset.resolve(...).identity` reads it back, and the `require` forms below write it as `<identity>`. - Folder shape: - `init.luau` (or `init.lua`) — module body. **Required.** Returns a table (conventionally named `M`). - `README.md` — instance-level documentation. **Required.** - `.metadata` — agent-editable tags + free-form fields. **Required.** ## How to create one ```luau asset.create("module", "<name>") -- Creates: /zero/source/<name>.module/ -- init.luau (canonical `local M = {} … return M`) -- README.md (instance README template) -- `folder` places it in a subfolder of /source, and that subfolder -- leads the identity: `{ folder = "lib" }` produces `lib.<name>`. -- `into` authors it inside a resolved container (a package, a toolbox), -- whose own identity leads the same way: asset.create("module", "<name>", { folder = "lib" }) asset.create("module", "<name>", { into = asset.resolve("myPkg.package") }) ``` ## How it operates 1. **Registration.** Writing `init.luau` into a `.module/` folder indexes the asset and registers the module path with the resolver. 2. **Loading.** The first `require("<identity>")` runs the file's body and caches the returned table. Subsequent requires from anywhere return the **same table** — this is the shared-state lever for "module-local" registries. 3. **Hot reload.** Editing the file re-runs the module body and folds what it returns into the table already loaded, so that table keeps its identity: a caller that captured it with `require` reads the new source's functions and values through the reference it already holds, and a later `require` returns that same table. A key the new source drops goes away; a key something set at runtime stays. The body's own `local`s start again from their initial values, so state that must outlive an edit lives in `modules.state()` (`guides { path: "core/scripting-and-tasks" }`). 4. **Identity resolution.** A module is reached by its `<identity>`, and where the caller lives decides which spelling of it resolves. For a module in a **world**, from a caller in that same world — another module, a component, a scene entrypoint, or an `execute` chunk: - `require("<identity>")` — the identity on its own, resolved against the caller's own root. It carries every folder segment, so a module created with `{ folder = "demo" }` is `require("demo.beats")`. - `require("@root::<identity>")` — the same root-relative resolution, written out. - `require(".sibling")` — a module in the same folder, by its bare name; `..name` steps up one folder, `...name` two. Logs, stack traces and hot-reload notices name that same module `@local.source.<identity>` — its key under the world source root. The `<identity>` tail of that key is the form above, so a trace reading `@local.source.demo.beats` is `require("demo.beats")`. For a module in a **library** — content under `/zero/source/libs/@<lib>/` — `@<lib>::` addresses that library's root from anywhere: `require("@builtin::modules.transform")`. Mounting a world as a library moves its files under such a root and flips the caller root to `@<lib>::`, which is what keeps the root-relative forms above resolving across the move. ## Discovery - `asset.list("module")` — every registered module. - `asset.inspect("<name>")` — public functions, source path, this type README. - `ls /zero/source/<name>.module` lists the files the folder holds. ## Authoring conventions - Return a single `M` table from `init.luau`. Top-level statements with side effects run on first require — useful for one-time initialization, dangerous if they touch the engine before it's ready. - Write exported functions as `typed function`, not `function`: the argument types are enforced at the call and the checker knows the signature, so a caller's mistake is reported where they made it. - Annotate exported functions with `--!desc` / `--!arg` / `--!return` / `--!example` so the LSP, `tools.list`, and `asset.inspect` surface them. A function with no `--!desc` is reachable only by someone already reading this file. - Declare a VALUE with `Field.<kind>(default, mode, description)`, and a table whose members are reached through a metatable with `--!members <TypeName>` — the latter gives the surface its accepted member set, its type, and its documentation from one table. See `guides { path: "core/authoring" }` for all four rules and `modules/api/engine/entity.module/members.module` for a worked member table. - Keep module state in module-local upvalues or in `modules.state()`. Globals leak across reloads. Module-locals start again from their initial values with each hot reload; the table `modules.state()` returns is the same table on both sides of every reload. - Prefer focused modules over kitchen-sink modules. If two halves of a module have no shared state, split them. ## Common pitfalls - **Cyclic requires.** A `require` chain that loops will return the partial table (the half built before the cycle was detected). Design for one-way dependencies. - **Engine-time side effects.** Don't `entity.spawn` at module top-level — the engine may not be ready. Expose an `M.init` and call it from a scene entrypoint. - **Hot-reload + module-local cache.** A module that caches expensive computation in upvalues loses that cache on reload — fine for dev, but be aware in performance work. - **`init.lua` vs `init.luau`.** Either works, `.luau` is canonical. - **Writing one while play runs.** A `/source` write made while play is running lands on the play shadow, and a guarded play-exit discards it unless it is kept. One `.module` write shadows `init.luau`, the `README.md` and the `.metadata` together. `vfs.write(path, bytes, { durable = true })` skips the shadow, and `vfs.promotePlayShadow` keeps what is already on it — the `core/vfs` guide has the model and what each route costs. ## Related types - `.component` — for entity-bound state + lifecycle hooks. - `.service` — generates content you don't have yet (a mesh, sound, texture, …) via a metered provider. - `.tool` — for a single agent-callable function with a YAML schema. - `.package` — to group several modules + components + scenes into one shippable folder. ## In the Inspector Exports: what the module exports (name, kind, signature), parsed from its source without running it, with **Check** (the LSP's diagnostics for its entry file) and **Open**.

# Buoyancy Floats the entity's rigid body on the sea. ```lua entity.find("barrel").component.add("Buoyancy", { density = 0.4 }) ``` The entity needs a dynamic `Physics` body. Position and orientation stay the physics world's — this component only adds the forces water exerts, so a floating body still collides, still takes impulses, and still falls when it is lifted clear of the water. | Field | What it does | |---|---| | `density` | Relative to water: the lower it is the higher the hull rides, and a body denser than water sinks. A hull settles a little deeper than the number alone asks for, so trim it until the waterline sits where it should. 0 releases the body. | | `damping` | How hard water resists the hull moving through it, as a fraction of the damping that settles it without overshoot. 1 is that critical value, 0 bobs indefinitely. Applied per column, so it steadies rolling as well as heaving. | | `angularDamping` | The same, for a hull turning. The rigid body carries it as its own angular damping while the hull is in the water, and it is the only thing that damps a spin about the hull's own vertical axis, which the per-column damping cannot see. | | `columns` | Grid resolution per horizontal axis over the footprint. 1 floats but cannot right itself; 2 is the smallest grid that produces a righting moment. | | `sizeX`/`sizeY`/`sizeZ` | The box that displaces water, in the hull's own space. All three at 0 measures it from what the entity draws. | `barrel:submersion()` reads how much of the hull was under water on the last step, and `barrel:waterline()` reads the world Y the surface stood at under it, wave motion included. Forces reach a rigid body only while the scene is playing, so a hull sits where it was placed in edit mode and settles onto the water when play starts.

# Ocean Puts a live sea on an entity. The component's fields ARE the sea state — wind speed and direction, choppiness, swell, foam, extent and detail — and the wave simulation, the GPU surface mesh and the material bound to the simulation are all rebuilt from them whenever the component wakes. That rebuild is what makes the ocean persistable. The simulation lives entirely in GPU buffers and a runtime mesh, none of which survive an engine restart; the component's settings do, and the whole sea is reconstructed from them. A scene with an ocean in it reloads into the same sea. The surface follows the viewer and covers `extent` metres around them, so one ocean is the whole sea however far anyone sails. `sampleHeight(x, z)` and `sampleDisplacement(x, z)` report where the water is — the same waves that are drawn — which is what a boat, a buoy or a swimmer floats on. Start from a `preset` (`calmClear`, `darkChop`, `darkRolling`, `heavySwell`, `whitecapped`, `murkyGrey`, `paleSwell`, `glassyDark` and `gale`) and override whatever the scene needs. Wind speed does most of the work: significant wave height goes as its square.

# ocean_assemble Unpacks one cascade's two transformed fields into the `(dx, height, dz)` displacement field the surface mesh reads, applying the `(-1)^(x+z)` sign alternation that undoes the centred-on-zero wave-vector grid the spectrum was built on. Height and horizontal displacement carry independent gains, so crest pinching (`choppiness`) can be dialled without changing wave height.

# ocean_displace Displaces the ocean surface mesh by one cascade, once per cascade per frame. The first cascade writes each vertex from the rest position stored in its UV and the rest accumulate onto it, so the mesh is rebuilt from a clean grid every frame instead of drifting. Cascades are sampled at the vertex's true world position — the mesh follows the camera, so its rest grid sits at a moving origin. The vertex normal accumulates each cascade's surface gradient (the ratio `n.xz / n.y`), which is how independent wave fields actually combine; per-fragment normal detail comes from the cascade normal maps in the surface shader, since the mesh is far too coarse near the horizon to carry it.

# ocean_evolve Advances one cascade's static spectrum to the current time — `h(k,t) = h0(k) e^{iwt} + conj(h0(-k)) e^{-iwt}` at the deep-water dispersion `w = sqrt(g|k|)` — and emits the two complex fields the inverse FFT consumes. The frequency is quantised to a multiple of `2*pi / loop_period` so the whole sea state repeats seamlessly instead of drifting as elapsed time grows. Field A packs the height and X-displacement spectra into one complex field (`H + i Dx`), which the Hermitian symmetry of both lets a single inverse transform separate again — two FFTs per cascade instead of three.

# ocean_fft Transforms one axis of an ocean cascade's complex field in place, as one dispatch per axis: a workgroup per line runs every Stockham auto-sort radix-2 butterfly stage against workgroup-shared memory, so a 256-wide transform costs one dispatch rather than eight butterfly passes and needs no bit-reversal permutation. Supports grids up to 512 per side. The axis, direction and scale arrive through the bound `plan` buffer rather than a `params:` uniform, because same-frame dispatches are chained into one submission and a uniform rewritten between them would not be seen per-dispatch.

# ocean_floor_displace Raises the seabed's flat grid into terrain: one gradient-noise field over world XZ, written into each vertex's height, with the analytic slope written into its normal. Runs when the mesh recentres rather than every frame. The terrain is still in the world; only the grid under it moves. It is a compute pass rather than the surface shader's `vertex()` hook so that every pass that draws the mesh, and everything that reads its vertex buffer, meets the same displaced geometry. The normal is the derivative of the noise rather than a difference of neighbouring vertices, so it stays correct where the grid is coarse — which, over a clipmap, is nearly everywhere. ## The collision patch The threads past the mesh write a square patch of the same field into `heights` as plain metres, row-major with the column along world X and the row along world Z — the layout a heightfield collider indexes. `plan[2]` gives the patch its world centre, its samples per side and its world span. It is the same call to the same function that raised the vertices. A second evaluation of the noise, in Luau or in a pass of its own, is a copy free to drift from the one that is drawn, and ground stood on a metre from where it is drawn is worse than ground with no collision at all — nothing reports it. ## Bindings | Buffer | Access | Contents | |--------|--------|----------| | `plan` | read | lane 0: `xy` mesh world origin, `z` vertex count, `w` noise period (m). lane 1: amplitude, lacunarity, persistence. lane 2: `xy` patch centre, `z` samples per side, `w` patch span (m). | | `vertices` | read_write | The mesh's vertex buffer, engine 23-word layout. | | `heights` | read_write | The collision patch, `side * side` f32 metres. | Dispatch `vertexCount + side * side` threads.

# ocean_floor_texture Grows the three tiling maps the seabed is built from: sand, rock, and the caustic web the sun draws on both of them. Albedo goes in `rgb` and height in `a`; the caustics map carries two independent phases in `r` and `g`. Generated rather than shipped as images. A stored texture is a binary, content-addressed asset, and a material blocked on a texture reference that never resolves never prepares — which leaves its entire uniform block unwritten and the surface black. Generating keeps the seabed on the same compute-texture path the cascade maps and the foam patterns already use. Run once per map at startup, each with its own seed. Every map tiles: each octave hashes its lattice modulo a period that divides the texture size. The caustics are constructed rather than painted. Sunlight refracting through a wavy surface lands as the light a patch gathers divided by the area it spreads over — the reciprocal Jacobian determinant of the refraction map. Writing the surface as a height field makes that map `p + k grad h`, so the determinant is that of `I + k H`; inverting it produces the sharp filaments and their crossing cusps, which are the places the determinant approaches zero and a finite bundle of light lands on almost nothing.

# ocean_foam The persistent whitecap field: a world-space region, following the viewer, in which foam accumulates where the sea folds and drains everywhere at a fixed half-life. Shading foam directly from the instantaneous fold makes it blink with the wave that caused it. This field is what gives a broken crest a wake of white behind it, and what the surface's `waves` foam layer is actually gated on. Run once per frame, after every cascade's `ocean_normals`. The two history buffers swap roles each frame; the caller binds whichever holds last frame's result as `previous`.

# ocean_foam_texture Grows the tiling greyscale pattern the three foam layers stamp on the water. It is generated rather than shipped as an image. A stored texture is a binary, content-addressed asset, and a material blocked on a texture reference that never resolves never prepares — which leaves its entire uniform block unwritten and the surface black, not merely un-foamed. Generating the pattern keeps foam on the same compute-texture path the cascade maps already use. Run once per layer at startup, each with its own seed. The noise tiles: every octave hashes its lattice modulo a period that divides the texture size.

# ocean_normals Differentiates one cascade's displacement field into a shading normal and a foam mask. Normals come from central differences of the displaced positions (so crest pinching is accounted for, unlike a height-only gradient), with wrap-around neighbours because the cascade tiles. Foam comes from the smaller eigenvalue of the horizontal displacement Jacobian: where it goes negative the surface has folded over itself, which is what a breaking wave is — so whitecaps appear from the same displacement that raised the crest rather than from a painted-on noise threshold. Fresh foam replaces the stored value immediately while old foam fades at `foam_decay` per second, leaving streaks behind broken crests.

# ocean_probe Resamples every cascade onto one small grid that the CPU reads back, so gameplay can ask where the water is without stalling a frame on the full simulation. Dispatched once per cascade: the first overwrites the grid, the rest add to it. `xyz` is the summed displacement in metres and `w` the strongest folding, so a caller can also ask whether the water at a point is breaking. The swell bank is deliberately absent — it is analytic and longer than the tile this grid covers, so `ocean.module` evaluates it directly on the CPU instead.

# ocean_spectrum Builds one ocean cascade's time-independent complex wave amplitude `h0(k)` from a JONSWAP directional spectrum: a Phillips energy core, Donelan–Banner directional spreading around the wind, a JONSWAP peak enhancement, and a `k_min`/`k_max` band limit that keeps each cascade to its own disjoint range of wave numbers. The result is randomised into a complex Gaussian so the same sea state produces a real random surface rather than a deterministic ripple. Runs when the sea state changes, not per frame — `ocean_evolve` animates the field it writes.

# Island lagoon The spectral ocean against a shore: an island rising out of a lagoon at a beach's slope, so one view holds every water depth from the waterline to open blue. Load it with `scene.load("@builtin::systems.oceans.demo.island_lagoon")`, then walk down to the water. ## What it shows - **Depth as colour.** The water column's absorption is per-channel, so the sea reads turquoise where the sand is a metre or two down and turns blue as the bed falls away. The gradient is the ground's own slope seen through the water, not a painted ramp. - **The seabed through the surface.** The bed is refracted, attenuated over the real path the light travelled, and lit by the caustic web the surface focuses onto it. - **Shoaling.** Chop dies as the bottom comes up — geometry and shading together — so the shallows are glassy while the open water stays crisp. - **The shoreline.** Wash along the waterline, foam that clings to breaking crests, and a sea that meets the sand instead of ending at it. - **A sun path over water.** The glitter track is the surface's own slope statistics under this scene's directional light. ## Things to try ```luau local Presets = require("@builtin::systems.oceans.modules.oceanPresets") Presets.names() -- nine sea states, calm to gale entity("lagoonSea").Ocean.preset = "gale" -- the same shore under a gale entity("lagoonSea").Ocean.seaLevel = 2.0 -- flood the beach ``` A preset is a whole sea — spectrum, swell, colour, all three foam layers and the seabed — so swapping one changes the water and leaves the island, the light and the sky exactly where they are. ## What it is made of - `@builtin::systems.oceans.demo.islandLagoon` — the terrain graph the island is baked from. - `Ocean` — the sea, bound to that landscape through its `ground` field. - A directional sun, an ambient fill, a `ProceduralSky` and a `PhysicalAtmosphere`. The ocean carries no light of its own: every reflection, the glitter and the foam's shading come from these.

# oceans guide The walkthrough for building a sea with the oceans package: putting an ocean in a scene, choosing a sea state and understanding which control does what, floating things on the waves, and what the simulation costs.

# oceanSeabed The ground under the sea: one gradient-noise field mixed between sand and rock, lit by the scene's own sun and ambient, with the caustics the waves above focus onto it added on top. The simulation drives the cascade displacement map, the sand and rock maps the compute pass generates, and the terrain's world origin on this material as the clipmap recentres; the blend threshold, the tiling and the caustic strength are authored here. Sea-state presets in `~.modules.oceanPresets` override these values.

# oceanWater The default open-ocean material the `Ocean` component applies: deep blue with per-channel absorption tuned for clear seawater, a near-mirror surface, and breaking-wave foam. The simulation drives the cascade normal maps, the cascade patch sizes and the scene-depth map on this material every frame; everything else is authored here. Sea-state presets in `~.modules.oceanPresets` override these values for paleSwell, gale and the rest.

# buoyancy Floats a rigid body on the sea the simulation is already drawing. ```lua local buoyancy = require("@builtin::systems.oceans.modules.buoyancy") buoyancy.attach(barrel, { density = 0.4 }) ``` Or attach a `Buoyancy` component next to the entity's `Physics` body and author `density` / `damping` / `angularDamping` / `columns` on it — the component calls this module every frame. ## A hull is a bundle of columns A grid is laid over the hull's footprint, and each cell stands for a vertical prism spanning the hull's full height. Every column measures the water above its own base, and carries the share of the displaced volume that implies, applied at its own position. That is what the grid is for. One force at the centre of mass can only push a body up and down; forces spread over the footprint push harder on the side that is deeper, which is what rights a hull that has been tipped over and what makes it pitch as a wave rolls under it. `columns = 1` is a single central column: it floats, but it cannot right itself. ## Density sets the waterline `density` is relative to water: the lower it is, the higher the hull rides, and a body denser than water sinks. `buoyancy.restingY(waterY, height, density)` gives the height at which a hull of that density displaces its own weight. A hull settles somewhat deeper than that height, and how much deeper moves with how long the frames are — a force applied from a script acts over a frame, while gravity is integrated by the physics step, so the two balance a little below where the arithmetic puts them. Densities up to about a half float on every frame time measured; above that a hull rides progressively lower and sinks outright on a long frame. Trim the number until the waterline sits where it should. The body's own mass comes from its rigid body, whether `Physics.mass` sets it or the solver derives it from the collider volume, and the buoyant force is scaled against it, so a hull floats at the same waterline whatever mass it was authored with — mass changes how briskly it gets there, not where it ends up. `mass` and `gravityScale` may be passed to `attach` / `configure` for a body whose rigid body says something else. ## Damping is measured against the hull's own spring Buoyancy is a spring: push a hull under and the water pushes back in proportion to how far, so it has a natural frequency of its own, set by how deep it has to sink to displace its own weight. `damping` is a fraction of the damping that would return it to its waterline without a single overshoot — 1 is that critical value, lower values let it bob on the way, 0 bobs indefinitely. Reading it as a ratio rather than an absolute rate is what keeps a dinghy and a barge equally steady at the same setting. It is applied per column against that column's own velocity, so it steadies rolling as well as heaving; a body spinning about its own vertical axis moves every column but their forces cancel in pairs, so `angularDamping` damps the hull's turning on top of it. That one is handed to the rigid body as its own angular damping rate for as long as the hull is in the water, so the physics step takes the spin down itself and can never overshoot the rest it is bringing the body to. Both scale with how much of the hull is actually in the water, so a body lifted clear of the sea falls freely. ## The hull's box The hull is measured from what the entity draws, in the entity's own space, so it stays the same box however the body is turned. Where that box sits comes with it, so a model drawn off its own pivot — a keel-pivoted boat, an offset child mesh — displaces water where it draws and carries its columns over that footprint. What an entity draws arrives over the frames after it is spawned, so the measurement is retried until it lands and a body keeps its place while it waits. `sizeX`/`sizeY`/`sizeZ` name a box explicitly — for a body whose visible mesh is not what displaces water, or one that draws nothing at all. That box is centred on the entity's origin, and it belongs at the size of the body that is actually there: the water pushes on the rigid body's own inertia, so a footprint much wider than the collider rocks a hull the body has no weight to steady. ## What it reads The water height comes from `ocean:sampleHeight`, the same wave field the surface renders, so a hull rides the waves that are on screen. With no ocean in the scene there is nothing to float on and the body is left to the physics world; pass `ocean` to pick one when a scene has several.

# ocean The oceans package's substrate. One `Ocean.create` call brings up a live sea: the GPU wave simulation, the surface mesh that renders it, the material bound to the simulation's output, and the coarse readback gameplay queries. The simulation is spectral and runs in cascades — independent wave fields over different patch sizes, each band-limited to its own range of wavelengths, summed into one surface. That is what gives detail at every scale (swell, wind waves, chop) while keeping each transform small. The surface is one mesh whose vertices a compute pass rewrites every frame, so no wave data crosses to the CPU for rendering. It is graded radially and follows the viewer, snapped to a wave-patch multiple so the sea stays put in the world while the mesh slides under it. `sampleHeight` / `sampleDisplacement` answer where the water is, from a small grid read back off the GPU a few times a second — enough to float a boat on the same waves that are drawn without stalling a frame on a round-trip. Both invert the horizontal wave displacement, so they return the surface point that actually ended up above the position you asked about. Use the `Ocean` component to place a sea in a scene; use this module directly to drive one from code.

# oceanClipmap Builds the ocean's geometry: concentric rings that double in extent and halve in density outward, the stitch strips that remove the T-junctions between them, and the skirt that carries the water out to the horizon. Returns the vertex and index data as Luau buffers, ready to upload straight into the compute buffers `ocean_displace` rewrites each frame.

# oceanFloor The ground the water is seen through. It spans the same extent as the clipmap, follows the viewer the way the surface does, and is shaded by `~.shaders.oceanFloor`. One noise field is the whole terrain: scaled it is the relief the seabed's vertex stage raises the grid into, and read again unscaled it picks between sand and rock. Over both moves the sun's caustic web, displaced by the horizontal displacement of the water directly above it. The seabed applies no absorption of its own. The water column belongs to the surface shader, which knows the real distance light travelled through water; attenuating here as well would darken the ground twice. Its three tiling maps are grown once by `ocean_floor_texture` — the same compute-texture path the cascade maps take — so the seabed carries no binary asset and no content reference that could fail to resolve. ```luau local Floor = require("@builtin::systems.oceans.modules.oceanFloor") local floor = Floor.create({ config = cfg, -- a resolved ocean config extent = 12800, -- the clipmap's own extent, metres prefix = "ocean1_floor_", name = "Seabed", }) floor:bindWave(cascadeDisplacementTexture, cascadeTile) floor:step(elapsed, viewerX, viewerZ) floor:destroy() ``` `Ocean` creates and drives one of these itself whenever the sea state's `floor` block is enabled, so a scene that uses the `Ocean` component gets a seabed without naming this module at all.

# oceanPresets Named sea states for the oceans package — `calmClear`, `darkChop`, `darkRolling`, `heavySwell`, `whitecapped`, `murkyGrey`, `paleSwell`, `glassyDark` and `gale`. Each name says what the water does, so a sea can be picked off the list without reading its values. A state is an `OceanConfig` fragment applied underneath whatever the caller passes to `Ocean.create`, so any single field can be overridden without giving up the rest. The states are laid out along the Beaufort scale, because wind speed is what determines wave height in a spectral ocean — the remaining fields shape character: how long the swell runs, how readily crests break, and what colour the water body is. `materialProperties` returns the appearance half of a preset, ready to apply to an ocean material.

# oceanQuality The four quality tiers: how finely the sea is resolved, as distinct from what sea it is. A tier owns the FFT grid per cascade, the clipmap's ring density, the swell band count, the whitecap field's resolution and whether screen-space reflections run. It never touches wind, spectrum shape or colour — those come from the preset, so the same named sea looks like itself on any machine.

# oceanScene The seam between the `oceanScene` render feature, which captures the colour and depth behind the water, and the ocean materials that sample them. `renderer.feature.create` hands back a handle rather than the feature module, so a shared module is how the half that fills the textures reaches the half that reads them.

# ocean_copy Copies the ocean's rendered surface into the scene target. ## Bindings | name | kind | |------|------| | `scene_depth` | `texture_depth` | | `scene_color` | `texture2d` | | `depth_out` | `storage2d (r32f)` | | `color_out` | `storage2d (rgba16f)` |

# oceanCalmClear The "Calm Clear" sea state, offered as `calmClear` in the ocean's preset list (slot 1 in the calm-to-gale progression). The lightest wind in the catalogue, at 4 m/s, over the brightest and clearest water it holds, above a shallow shoal. A complete `oceanPreset` configuration: spectrum and swell, colours, fresnel, all three foam layers, the seabed and its caustics, subsurface scattering, screen-space reflections and the sun sparkle.

# oceanDarkChop The "Dark Chop" sea state, offered as `darkChop` in the ocean's preset list (slot 2 in the calm-to-gale progression). A brisk wind chopping the darkest water in the catalogue, with almost no swell running underneath it. A complete `oceanPreset` configuration: spectrum and swell, colours, fresnel, all three foam layers, the seabed and its caustics, subsurface scattering, screen-space reflections and the sun sparkle.

# oceanDarkRolling The "Dark Rolling" sea state, offered as `darkRolling` in the ocean's preset list (slot 3 in the calm-to-gale progression). Dark water rolling under a long swell, on the least choppy surface in the catalogue. A complete `oceanPreset` configuration: spectrum and swell, colours, fresnel, all three foam layers, the seabed and its caustics, subsurface scattering, screen-space reflections and the sun sparkle.

# oceanGale The "Gale" sea state, offered as `gale` in the ocean's preset list (slot 9 in the calm-to-gale progression). The strongest wind in the catalogue, at 38 m/s, raising a fully wind-driven sea under the heaviest surface foam. A complete `oceanPreset` configuration: spectrum and swell, colours, fresnel, all three foam layers, the seabed and its caustics, subsurface scattering, screen-space reflections and the sun sparkle.

# oceanGlassyDark The "Glassy Dark" sea state, offered as `glassyDark` in the ocean's preset list (slot 8 in the calm-to-gale progression). No swell at all and the highest standing-wave ratio in the catalogue: a still, strongly refracting surface over near-black water. A complete `oceanPreset` configuration: spectrum and swell, colours, fresnel, all three foam layers, the seabed and its caustics, subsurface scattering, screen-space reflections and the sun sparkle.

# oceanHeavySwell The "Heavy Swell" sea state, offered as `heavySwell` in the ocean's preset list (slot 4 in the calm-to-gale progression). The largest and longest swell in the catalogue, running through mid teal-green water. A complete `oceanPreset` configuration: spectrum and swell, colours, fresnel, all three foam layers, the seabed and its caustics, subsurface scattering, screen-space reflections and the sun sparkle.

# oceanMurkyGrey The "Murky Grey" sea state, offered as `murkyGrey` in the ocean's preset list (slot 6 in the calm-to-gale progression). Grey, murky water whose reflections fall away close to the eye and which carries no glitter at all. A complete `oceanPreset` configuration: spectrum and swell, colours, fresnel, all three foam layers, the seabed and its caustics, subsurface scattering, screen-space reflections and the sun sparkle.

# oceanPaleSwell The "Pale Swell" sea state, offered as `paleSwell` in the ocean's preset list (slot 7 in the calm-to-gale progression). A big swell under one of the lightest winds in the catalogue, through the palest blue subsurface transmission it holds. A complete `oceanPreset` configuration: spectrum and swell, colours, fresnel, all three foam layers, the seabed and its caustics, subsurface scattering, screen-space reflections and the sun sparkle.

# oceanPreset A complete sea state for the ocean system: everything `ocean.create` needs to stand up a specific sea, from the wave spectrum to the seabed under it. Each `.data` instance is one named preset offered in the ocean's preset list. ## Fields - `key` — the name the preset answers to in `ocean.create({ preset = ... })` and the presets API. Stable; world content refers to it. - `label` — the human-readable name shown in pickers. - `order` — the preset's slot in the calm-to-gale progression the list is offered in (1 = flattest). - `seed` — the spectrum's random seed. - `waves` — the FFT spectrum: wind speed and direction, choppiness, gravity, JONSWAP gamma, spectral sharpness, standing-wave ratio, animation speed, and a global amplitude on top. - `cascades` — the three simulation bands: per-band enable, amplitude and world-space tile scale in metres. - `gerstner` — the analytic long swell layered under the FFT bands: wavelength and its spread, amplitude, wave count, directional spread. - `clipmap` — the surface mesh: base tile size in metres and ring count. - `color` — the water column: absorption rates authored as a hex triple (decoded to per-channel 1/m extinction), transmission and body colours, and the depth assumed where nothing stands behind the water. - `fresnel` — the mirror: distance fade start/power, index-of-refraction ratio, normal strength, screen-space refraction strength. - `foam` — the three layers: `surface` lace, `waves` whitecaps (with persistence, optional `breaking` window and `placement` mask), and the `shoreline` wash. - `floor` — the procedural seabed and its `caustics` web. - `shore` — how deep the bottom starts taking the waves (`shoalDepth`, metres); omitted, the ocean's default shoaling band applies. - `sss` — subsurface scattering through backlit crests. - `ssr` — screen-space reflections. - `sparkle` — the sun's specular glint. Colour-valued fields are authored as `#rrggbb` strings and decoded to linear RGB by `Presets.color` on the way to the GPU — including `absorptionColor`, whose channels are extinction rates rather than a colour.

# oceanWhitecapped The "Whitecapped" sea state, offered as `whitecapped` in the ocean's preset list (slot 5 in the calm-to-gale progression). A hard wind raising the steepest crests in the catalogue, whose foam is the heaviest and the slowest to fade. A complete `oceanPreset` configuration: spectrum and swell, colours, fresnel, all three foam layers, the seabed and its caustics, subsurface scattering, screen-space reflections and the sun sparkle.

# oceanScene Copies the colour and depth of everything drawn behind the water into textures the ocean surface material can sample. A surface shader cannot bind the frame's own depth buffer or colour target while drawing into them, and the water needs both: depth gives the length of the water column, and colour is what refraction bends and what screen-space reflections march through. Both copies run at `afterOpaque` and are published through `~.modules.oceanScene`, which is where the ocean materials pick them up.

# oceanFloor The seabed under the spectral ocean: sand where the ground has settled, rock where it has not, lit through the water by a moving web of focused sunlight. One noise field decides the whole terrain. Scaled, it is the relief the vertex stage raises the mesh into and the normal that shades it; unscaled, the same field picks between sand and rock — so rock outcrops stand on the high ground and sand fills the hollows, because the two are readings of one surface rather than independent patterns laid over each other. Both ground maps carry albedo in `rgb` and height in `a`. The height is differenced into a detail normal that rides on the terrain's own slope as a gradient, so relief accumulates rather than one normal replacing the other. The caustics are two layers of the caustics map scrolling against each other at slightly different scales and in opposite directions, displaced by the horizontal displacement of the water directly overhead — which is what makes the web ripple with the surface instead of sliding across the ground as one rigid sheet. Each colour channel is read at its own small offset, giving the chromatic fringe focused light through a dispersing medium has. The seabed applies NO absorption of its own. The water column above it belongs to the water surface, which knows the real distance the light travelled through water; attenuating here as well would darken the ground twice. The mesh follows the viewer, so `floor_center` carries where it currently sits and every terrain and texture lookup is made in world space. That is what keeps the ground still while the mesh slides beneath it.

# oceanSurface The water surface of the spectral ocean. Geometry arrives already displaced by `ocean_displace`, so this shader only decides what the surface looks like: the normal summed across cascades as gradients (which is what adds when wave fields overlap), a water column shaded by per-channel Beer–Lambert extinction over the distance to whatever lies behind it, Fresnel reflection from the scene's own reflection probes, subsurface scattering through backlit crests lit by the scene's directional light, a sharp sun-glitter lobe, and foam from the simulation's own breaking-wave mask plus a shoreline band. Opacity is the extinction rather than an authored constant, so colour and transparency stay consistent from a turquoise shallow to a near-black deep. Works from below as well as above.

# Package (asset type) A package is an asset — a `<Name>.package/` folder that bundles components, modules, scenes, presets, tools, and any other typed sub-assets under one identity, installed into a world as one unit. Packages are how authoring sets get distributed across worlds. A **library** is the addressable root scope content resolves under (`@builtin`, `@<name>`) — a whole world mounted into this one under a namespace, via `zeromind.installLib` / `world.installLibrary`. A package is an asset that lives inside such a root, and one library holds as many packages as its author put there. A package is installed by guid the way every asset is (`zeromind.install`, `zeromind.installAsset`). ## When to use one - You're authoring a coherent feature suite (character controller stack, voxel engine, UI kit, animation library) and want to ship it as one install target. - You want a stable identity worlds can install and resolve sub-assets against (`@<lib>::pkg.sub_module`). - You want versioning + a per-package metadata layer that travels with the contents. If you're authoring inside a single world and don't need a separate install lifecycle, you don't need a package — drop your `.component` / `.module` / etc. directly in `/zero/source/`. Packages are for cross-world distribution. ## Where it lives - Source: `/zero/source/.../<Name>.package/` (or, for legacy packages, a folder containing `package.yaml` at its root). - Identity: `<Name>` (the `.package` suffix collapses in identity — mirrors `.module`). A file at `<Name>.package/<sub>/init.luau` resolves under the same identity it would at `<Name>/<sub>/init.luau`. - Folder shape (container-style — open child set): - `package.yaml` — metadata (name, version, description). **Required.** - `README.md` — instance documentation. **Required.** - `.metadata` — agent-editable tags + free-form fields. **Required.** - Sub-asset folders: any combination of `.component/`, `.module/`, `.scene/`, `.preset/`, `.tool/`, `.toolbox/`, `.material/`, `.shader/`, etc. The validator permits unlisted children (`allow_unlisted: true`) by design — packages are open containers. ## How to create one ```luau asset.create("package", "<Name>") -- Creates: /zero/source/<Name>.package/ -- package.yaml (metadata scaffold) -- README.md (instance README template) -- `folder` places it in a subfolder of /source instead of the root: asset.create("package", "<Name>", { folder = "systems" }) ``` Then scaffold sub-assets inside it: ```luau local pkg = asset.resolve("<Name>.package") asset.create("component", "Spinner", { into = pkg }) asset.create("module", "util", { into = pkg }) ``` ## How it operates 1. **Registration.** Writing `package.yaml` indexes the package with the package registry. 2. **Install.** A package is installed by guid, the way every asset is: `zeromind.install` from the shared library, or `tools.use("zeromind", "installAsset", <guid>)` inside the engine. The install writes the package's files (and the deps its `.refs` record) into this world's source, so its sub-assets resolve here. `tools.use("zeromind", "preview", <guid>)` reports what an install would write before it writes anything. 3. **Sub-asset resolution.** Because `.package` collapses in identity, sub-asset paths work whether the package folder is suffixed (`<Name>.package/<sub>`) or not (`<Name>/<sub>`). 4. **Updates.** `tools.use("zeromind", "updates")` lists installed content with upstream changes available; re-running the install pulls them. 5. **Metadata.** `package.yaml::name` overrides the folder stem if present (rare); `version` + `description` are surfaced in the package index. 6. **Hot reload.** Edits to sub-assets hot-reload as normal; edits to `package.yaml` reload package metadata. ## Discovery - `asset.list("package")` — every registered package. - `asset.inspect("<name>")` — sub-asset catalog, source, this type README. - `ls /zero/source/<Name>.package` lists the files the folder holds. - `library.list()` — the library assets registered in this world, including the ones packages under an installed library contribute. ## Authoring conventions - Name packages by their feature (`voxels`, `cameraRigs`, `dialogSystem`), not by their owner — the host library is the `@<lib>::` scope prefix. - Cluster cohesive sub-assets together. A "character controller" package should ship the controller component, its preset configs, its supporting modules, and a demo scene — not just the component. - Document the package's surface in `README.md` — what install installs, what each sub-asset does, how they relate. Agents reading `cat /zero/source/<Name>.package/README.md` get the full picture in one shot. - Version conservatively — breaking a package means breaking every world that installed it. Use semantic version bumps. ## Common pitfalls - **Missing `package.yaml`.** Without it the folder isn't recognized as a package even if it has a `.package/` suffix. - **Dependency installs.** A package that depends on another package must declare it (in `package.yaml::dependencies` once supported) and the parent world must install dependencies in order. - **Identity collapse.** Sub-asset paths skip the `.package` suffix. Don't include `.package` in `require` strings. ## Referencing inside a package: the `~` rule `~` means **this package**, resolved structurally from the referring file's own location. It is the only package-specific syntax. It is rename-safe (no package name is ever written) and library-agnostic (it never names the host library, so it survives `@builtin` being renamed or the package being mounted elsewhere). `~.tail` maps to `<pkg>.package/tail` from anywhere inside the package. | Referencing from | Use | Example | |---|---|---| | An asset/module **inside this package** | `~.tail` | `require("~.modules.myThing")`, `shader: "~.shaders.myThingBlend"` | | A **different package** under the same root | root-relative identity | `require("@root::systems.otherPkg.modules.x")` | | A **different library's** public API (a deliberate external dependency) | `@otherlib::…` | `require("@physics::modules.rigidbody")` | **Never write `@builtin::` (or any host-library name) to reference your own package** — that couples the package to the library it currently lives in and breaks if the library is renamed or the files move. Use `~.`. It works from Luau `require()` and from asset-reference strings in data files (a material's `mat.yaml` `shader:` field, a component's default asset ref); the engine resolves it against the referring file's own package. `asset.resolve` takes a `~.` name the same way, against the package of the file that calls it: `asset.resolve("~.materials.myThingStandard", "material")`. `~.` is the package-relative self-reference; `@root::` is the root-relative one (the library root, or the world source tree for non-library content). The `core/requiring-modules` guide covers the root model in full. A package that ships substantial functionality should include a `.guide` asset (a `<name>.guide/guide.md` folder anywhere under the package); the `guides` tool discovers it live, so collaborators find the system the way they find built-in guides. A package's test suite reaches the shared `Test` framework through its enclosing asset: `local Test = asset.containing(__FILE__).modules.shared` (`asset.containing` returns the deepest enclosing typed asset, the `.testSuite`, not the outer `.package`). ## Related types - Any of `.component`, `.module`, `.scene`, `.preset`, `.tool`, `.toolbox`, `.material`, `.shader`, `.style`, `.service`, `.importer` — packages bundle these. ## In the Inspector Package: the name, version and description package.yaml declares, how many things the package holds and what they are, and **Open** for package.yaml. A package.yaml that does not decode is listed under Problems with the decoder's error.

# Component (asset type) A component is a reusable behavior + data unit attached to an entity. The component file declares public fields, methods, and lifecycle callbacks; the engine instantiates one per attachment and drives its hooks every frame. Components are the primary unit of gameplay code — movement, AI, animations, UI panels, network sync, and per-entity state all live here. ## When to use one - You need per-entity state that survives across frames. - You need per-entity behavior driven by engine lifecycle hooks (`start`, `update`, `destroy`). - You want to expose configurable fields to designers / `entity.spawn` callers / scenes without code changes. If you need a global service that outlives any entity, use a `.service` instead. If you need a stateless pure-function library, use a `.module`. ## Where it lives - Source: `/zero/source/.../<Name>.component/` - Identity: `<Name>` (the `.component` suffix strips from the identity, but the folder retains the suffix on disk). - Folder shape: - `init.luau` (or `init.lua`) — declares the component. **Required.** - `README.md` — instance-level documentation. **Required.** - `.metadata` — agent-editable tags + free-form fields. **Required.** The structural contract is enforced by `asset.validate` against this type's `type.yaml`. ## How to create one Always start with the scaffold — it guarantees the folder shape matches `type.yaml` from the moment it's on disk: ```luau asset.create("component", "<Name>") -- Creates: /zero/source/<Name>.component/ -- init.luau (canonical declare + public block + hooks stubbed) -- README.md (instance README template) ``` After scaffolding, edit `init.luau` to fill in the actual fields and behaviour. The component registers as soon as the file is written — hot-reload is automatic; no engine restart required. ## How it operates 1. **Registration.** Writing `init.luau` into a `.component/` folder indexes the asset, mints a guid (in the `.meta` sidecar), and surfaces the type to the engine's component registry. Same-frame visible to `entity.component.add`. 2. **Attachment.** `entity(id).component.add(name, data)` (or the batch form `tools.use("entityOps", "addComponents", targets, { [name] = data })`) attaches an instance. The `data` table's fields override the component's declared defaults; omitted fields take the declared default. The `data` values are copied into `public.*` BEFORE `awake()` runs. 3. **Lifecycle.** The hooks run in this order: - `awake()` — same frame as attach, immediately after the data copy. Initialise state, set up native bridges, register with other systems. Other components on the same entity may not have awoken yet. - `start()` — the next frame. Every component on the entity has completed `awake()` by then, so cross-component setup is safe here. - `update(dt)` — same frame as `start()`, then every frame after, for as long as the gameplay clock is running. `fixedUpdate(dt)` runs beside it on the fixed timestep; `editorUpdate(dt)` runs while the clock is held. Which of them ticks is decided by `engine.mode` AND `engine.paused` together — see **Per-frame hooks and the two axes** below, and `man modes`. - `onDestroy()` — when the component is removed via `component.remove` or when the owning entity is despawned. Release resources, drop native ECS components. For the full list (`onEnable`, `onDisable`, `fixedUpdate`, `editorUpdate`, `onPropertyChanged`, `onAssetReload`, `onModuleReload`, `onBeforeSave`, …) and the timing details, **read `man components` — that is the canonical lifecycle reference. Generic component patterns (declare blocks, public fields, sync, ECS bindings, typed methods) all live there.** 4. **Public surface.** Fields declared in `public` are inspectable, editable in the inspector, and persist with the entity. Methods are declared on that same table with a colon — `typed function public:method(args)` — and every one of them takes the component ref as `self`, so a caller invokes it with a colon too: `entity(id).component.get(name):method(args)`. That is the one calling convention a component ref answers to: the reflection methods `ref:fields()` / `ref:getField(name)` / `ref:setField(name, value)` take the same spelling. A function the chunk declares at file scope (`function helper()`) is the component's own, reachable from its hooks under its bare name; `public` is what the ref carries. 5. **Settings and the Inspector card.** `type.yaml` names the component's settings schema as `settings: { schema: { instance: "init.luau", export: "public" } }`: the `public` table IS the schema, and its values live on each entity the component is on, so `asset.schema(componentRef)` answers the Field descriptors and no values file exists. On an entity the Inspector shows the component as a card whose generic `settings` section edits those fields as typed controls, each edit checked against the schema and written to the live component as one undoable operation. `type.yaml` also names `inspector: { instance: "inspector.luau" }`: a component that ships an `inspector.luau` beside its `init.luau` shapes its card — the file returns `{ sections, replace, order }` (see `assetTypes/README.md`, "`inspector:`"), each section's `build(ctx)` reading `ctx.component` (the live component) and `ctx.selection.id` (the entity). `SceneModule.component/inspector.luau` replaces `settings` with the bound module's declared inputs. 6. **Events.** An `events` block declares typed moments the component fires from inside — `events = { onHit = Event({ dmg = Field.number(0, NoSync) }) }`. The owner fires with `events.onHit:fire({ dmg = 10 })`; outside code subscribes through the proxy's subscribe-only facade, `entity(id).component.get(name).events.onHit:connect(fn)` (`:once` / `:wait` too). Pass `Sync` as the event's second argument to replicate a fire to other peers. Events let one component react to another's moments without polling. Full reference: **`man components`**, Events section. 7. **Hot reload.** Editing `init.luau` reloads the component definition; live instances are reconciled with the new declaration in-place, and each crosses one lifecycle boundary: `onDestroy()` ends the running life, then `awake()` and `start()` construct the one that replaces it, and `update()` resumes on the next frame. `public` and `private` values carry across; module-level `local`s belong to the chunk, so the new life starts with them at their initial values and its `awake`/`start` are what fill them in. Whatever the old life handed elsewhere — a subscription, a shared registration, a spawned entity — is released in `onDestroy`, the call that pairs with the construction about to run. An edit that leaves the source byte-identical crosses no boundary at all. A field carries its value across when something stated it: a key of the `data` table the instance was attached with (a scene record's data is that table), or a write made since. Every other field takes the edited source's declared default, so changing a default reaches every instance that left the field to it. An instance that states its own value for a field whose default the edit changed keeps that value, and the reload logs a `[HotReload]` warning naming the field, the entity, the value kept and both defaults. ## Discovery - `asset.list("component")` — every registered component (engine + world + libraries). - `asset.inspect("<name>")` — identity, scope, public fields, lifecycle methods, source path, and this type README. `detail` carries the component's declared `fields`, `methods`, and `events`, parsed from its source — `tools.use("assets","describe", "<name>")` renders it as markdown, so a component's events are visible without opening its source. - `ls /zero/source/<Name>.component` lists the files the folder holds. - `entity(id).component.list()` — components attached to an entity. ## Per-frame hooks and the two axes `engine.mode` (`"edit"` / `"play"`) and `engine.paused` (the gameplay clock) are independent, and the per-frame hooks read them separately: - `update(dt)` / `fixedUpdate(dt)` tick while **the gameplay clock is running** — whichever mode the engine is in. - `editorUpdate(dt)` ticks while **the clock is held** — because the mode is `edit`, or because play is paused — and also alongside `update` whenever edit is running. Which gives four states, and this table is the contract: | `engine.mode` | `engine.paused` | hooks that tick | |---|---|---| | `edit` | `true` | `editorUpdate` | | `edit` | `false` | `update`, `fixedUpdate`, `editorUpdate` | | `play` | `false` | `update`, `fixedUpdate` | | `play` | `true` | `editorUpdate` | Entering edit sets `paused = true` and entering play sets it back to `false`, so a session that never writes `engine.paused` only ever sees rows 1 and 3 — which is where the shorthand "`update` is the play tick, `editorUpdate` is the edit tick" comes from. It is the two default rows of a four-row table, not the rule. **Row 2 is the one that surprises.** With `engine.paused = false` in edit — set by hand, or by a tool that advances the gameplay clock to sample it, such as a `capture.collage` given a `duration` — `update` and `editorUpdate` both fire, once each, every frame. A component that declares both and routes them to one body therefore runs that body **twice per frame**: ```luau local function drive(dt) ... end function update(dt) drive(dt) end function editorUpdate(dt) drive(dt) end -- twice per frame in row 2 ``` Nothing reports the doubling; it reads as an animation running at twice its intended speed. To get exactly one tick per frame in every row, ask which axis you meant and answer it in the body: ```luau function update(dt) drive(dt) end function editorUpdate(dt) if engine.paused then drive(dt) end end ``` A scene `entrypoint.luau` declaring the same two hook names is dispatched by the scene loader, not by this table: there `update` needs play AND running, `editorUpdate` needs edit, and play-paused ticks neither. Read `man scenes` before carrying a component's rule to an entrypoint. ## Authoring conventions - Annotate public fields with `--!desc` so the inspector + LSP show documentation alongside the field name. - Declare lifecycle hooks (`start`, `update`, `destroy`) explicitly rather than relying on engine defaults — readers can see at a glance what runs when. - Keep `update(dt)` cheap — it runs every frame per instance. Move heavy work to `start`, to a service, or behind a job (`man jobs`). - For multi-entity batching, prefer `tools.use("entityOps", "addComponents", targets, components)` over a loop of `entity(id).component.add` — it takes many targets and many components in one call. ## Common pitfalls - **Naming.** The component identity is the folder stem with `.component` stripped (e.g. `<Spinner>.component/` → identity `Spinner`). Don't repeat the suffix in the identity passed to `component.add`. - **`init.lua` vs `init.luau`.** Either is accepted (it's a `one_of_group: "entrypoint"`), but `.luau` is canonical. Mixing both in one folder is invalid. - **`update` in edit mode.** It runs whenever the gameplay clock is running, and entering edit stops that clock — so `update` is idle in a freshly-entered edit session and ticks again the moment anything sets `engine.paused = false`. Use `tools.use("wld", "play")` to test update logic under the mode it ships in; `tools.use("wld", "edit")` to return. See **Per-frame hooks and the two axes** above. - **Renaming.** Renaming the folder changes the identity. Update every `component.add(<oldname>, ...)` call and the scene JSON entries that reference it. ## Related types - `.module` — pure-function library, no per-entity state. - `.service` — globally-scoped behavior, no per-entity state. - `.preset` — a captured component configuration, replayable into `component.add` without re-typing fields. - `.bundle` — entity hierarchies that may carry component attachments as part of the bundle. ## In the Inspector Fields: its execution order, hooks, and how many methods and events it declares, then the fields its `public` table declares as read-only typed controls holding their defaults, with **Check** and **Open** for its entry file. Instances: a link to every entity carrying it. What its card shows on an entity comes from the component's own `inspector.luau`.

# proc.builder What a graph builder hands the author, in the call form: `proc.define(function(g) ... end)`. - `g.<name>(args)` adds a node of the node asset the name resolves to, by asset identity: the nodebox and the node's folder name (`g.points.disc`), a path (`g["/zero/source/fx/ring.procNode"]`), `~` (the nearest package, effect or world root: `g["~/ring"]`), a guid, or a short name (`g.disc`). A name that matches two nodes, and a name that matches none, are errors that name the candidates. Each call is recorded in the graph by the node's guid. Arguments are a table naming inputs or positional values in the node's input order. - What a call answers: a node with one output answers that output's socket, a node with several answers a record of sockets by output name (`local f = g.core.normals.face(geo); f.geometry, f.area`), a node with none answers nothing. The record does not depend on declaration order. - `g.op.<name>(args)` (and `proc.op.<name>`) adds a node of an op, for library nodes built on the ops. - `g:input(name, default, opts)` is typed by the default: `Float`, `String`, `Bool`, `Vec3`, `Color`, `List<T>`, `Record` with its fields. `opts` takes `min`, `max`, `options`, `description`, `optional` and `type` for a default that does not state its type or no default at all. An empty table default with a stated `type` is that type's empty value (`g:input("entities", {}, { type = "List<Entity>" })`). - An input with `options`, or of type Bool or String, is a plain value while the graph is built: `g:input` answers the value itself, `if` over it is allowed, and it passes into calls as a constant. Number and vector inputs are sockets. The graph records the plain values it was built with in `graph.plain`, and each such declaration in `graph.inputs[name].plain = true`. - Sockets take `+ - * / % ^ // ..` and unary minus, `math.*` and `vector.*` (each a `math.<name>` node; `vector.create` is `math.vec2`, `math.vec3` or `math.vec4` by its component count), `x.name`, `x.name = v` and `x[name] = v` for a computed name (which rebind `x`), `x[class][name]`, `x[n]`, and `for index, item in list do ... end`. A source loaded through `builder.prepareSource` reads plain `math`, `vector` and `rand` over sockets unchanged; `define` loads a node or graph entry that way when it names them. - `g.compare(a, op, b)`, `g.where(cond, a, b)`, `g.pick(choice, alternatives)`, `g:fold(n, init, fn, opts)`, `g:state(name, columns)`, `g:step(dt, substeps, fn)`, `g:check(cond, message)`, `g.has(geometry, class, name)` and `g.copy(socket)` record the constructs the evaluator knows. - `g:check(cond, message)`: a `cond` known while the graph is built refuses the build with the message (a true one records nothing); a `cond` that reads a socket is recorded for the plan or the cook to answer. The build of a node's own defaults, which is what indexes the node, holds such a refusal instead of raising it (`graph.refusals`), and `forInputs` states it where the node is called or cooked as it stands, so a check over a plain input fires when the call gives it the refused value. - A plain Luau table filled inside a `for` body over sockets keeps one element (`rings[#rings + 1] = v`, `table.insert(rings, v)`): the body is one pass for every item. `builder.check` refuses it with the code `socket-loop-append`, naming the form to write: a local declared before the loop and assigned inside it, read after the loop, where it is the list of every pass's value. - `g.copy(value)` of a record or a list written in the graph (`g.copy({ total = 0 })`) is a value of its own that member writes rebind, so a `for` body that fills it carries it from pass to pass. - A class view made with a socket key (`names[i]`) and read as a value is a node of the scope it was made in, whichever loop body first reads it. - A `for` body is one pass that stands for every item. `index` is the item's place (a socket, from 1). A value built outside the body that the body reads or assigns (`geometry[class][name] = v`, `record.name = v`, `record[name] = v`) is carried: each pass starts from what the pass before left, the first from the value as it stood before the loop, and after the loop the value is what the last pass left. The loop records the carries in `scope.carries[id] = { init, result }` and the refs `loop_index`, `loop_carry` (the value at the start of a pass) and `loop_result` (the value after the loop). A value the body only reads reads as it was. The emitter writes a carrying loop as it was authored: a local that starts as `g:copy(value)`, the body's assignments to it, and the loop reading that local after it (`proc.emit`). - `g.clock.placement` (16 numbers, column after column), `g.clock.inverse`, `g.clock.rotation` (`{ x, y, z, w }`) and `g.clock.entity` answer where the graph stands in the scene it is cooked in: each is a `construct.scene` node that reads the scene the cook is handed (a graph standing on no entity has the identity placement and no entity). `g.transform.point(p)`, `g.transform.direction(d)` and `g.transform.rotation(q)` carry a world position, direction or quaternion into the graph's space through the inverse placement; each takes plain values, sockets or Fields. - `g:fold(n, init, fn, { stop = "changed" })` or `{ stop = function(before, after) return <Bool> end }`; `fn` returns the state only. The fold runs `n` passes and ends early at the first pass whose stop holds. - `g.element` is the element a Field evaluates over: `g.element.id` (Int), `g.element.P` (the position leaf that `fieldc.withPosition` substitutes, also written `g.element.point.P`) and `g.element.<class>.<column>` for a column of the domain the field stands in. Each read is a socket, so `g.element.id * 1.0` is a math node. - `rand.unit(seed, ...scope, id)` (a global in a node source, also `builder.rand.unit`) is the Float field of unit draws keyed by the seed, the scope (`graphId, nodeId, channel`, or `graphId, compositePath, nodeId, channel`) and the element `id`, last (`g.element.id`). It adds an `io.luau` node `{ module = "@builtin::systems.procgen.proc.fieldc.leaves", fn = "rand", args = { seed, { ...scope }, id }, returns = { "Any" } }` and answers its `value`. - `geometry.names[class]` lists the attribute names a class holds (a list socket the plan answers); `geometry[class].count = n` assigns the domain count; `geometry.material = m` assigns the material. `names` is read by that name on any socket: what is read off it by a class (`geometry.names.point`) lists the names, and any other read (`record.names[2]`, `record.names`) is the member a record holds under that name, as `count` and `keys` are. `material` is assigned by that name on any socket. - A member, an item, a column or the names of a value built outside a fold, step or stop body that the body reads first is a node of the scope the value was built in: the body and every later fold read the one value, which the plan writes once. A read keyed by a socket of the body (a fold's index) stays in the body. - `g.clock.time`, `.frame`, `.delta` and `.duration` are sockets; `.fps`, `.frames`, `.loop` and `.realTime` are the timeline's values. - Luau's `< <= > >= == ~=`, `and`, `or`, `not` and `if` over a socket have no value while the graph is built. `builder.check(source)` names each one with the `g.*` form to write, and `define` holds a node or graph entry to it. Plain inputs are not sockets to the check. A plain Luau table indexed by a socket (`LANES[values.type]`) answers nil while the graph is built, so the check refuses it with the code `socket-table-index`, which names `g.pick`. - A list of values holds a nil as a value: `{ a, nil, b }` is three, and the second is a constant of nothing. ## Building a graph for other plain values A graph whose plain inputs change structure is built again for the values a cook was given. - `builder.forInputs(graph, inputs)` answers `graph` while its plain inputs hold what the build used, else the graph built again from `graph.source` with the values `inputs` states (an input it leaves out takes its default); the result is cached by the source text and the values, so a node written again is built again. It answers `nil, reason` when the source cannot be built again or a value is outside the input's options. - An optional input with no default (`g:input(name, nil, { optional = true })`) is nil while the graph is built for a call that leaves it unwired, and its socket otherwise, so `if input == nil then ... end` in a node source is decided by what the call wired. The declaration states `wiring = true` and the graph records the wiring it was built for in `graph.wiring[name]`; `forInputs` builds the graph again for a cook given no value for such an input (`values[name] == false` states none in `rebuild` and `withInputs`). - `builder.rebuild(graph, values)` builds again unconditionally; `builder.withInputs(values, fn)` runs a function that calls `proc.define` and gives that graph the values. A node asset called with a plain value records it as a constant param; the evaluator reads a node's graph through `forInputs` with those params. ## What a graph records A call-form graph states `surface = "call"`. Each node it makes carries `call = true`, `seq` (the order it was made in, which the emitter writes it back in) and `scope`. A node asset is `op = { __ref, type = "procNode", name }`; an op is its id string; a construct is `op = "construct.<kind>"` with `construct = <kind>`. `graph.scopes` holds each `for`, `fold`, `stop` and `step` body, `graph.states` each `g:state`, `graph.plain` the plain input values. The `inputs` of a construct node are refs (a constant is `{ kind = "const", value }`); `params` are constants. | construct | inputs | params | answers | |---|---|---|---| | `member` | `value`, `name` | | the member of `value` | | `member_set` | `value`, `name`, `to` | | `value` with the member written | | `item` | `list`, `index` | | the item | | `column` | `geometry`, `class`, `name` | | the column read (a read of `count` is the domain count) | | `column_set` | `geometry`, `class`, `name`, `value` | | the geometry with the column written | | `column_remove` | `geometry`, `class`, `name` | | the geometry without the column | | `count_set` | `geometry`, `class`, `count` | | the geometry with that class's domain count set to `count` | | `material_set` | `geometry`, `material` | | the geometry with its material set | | `names` | `geometry`, `class` | | the List of attribute names the class holds, answered at plan | | `has` | `geometry`, `class`, `name` | | a Bool answered at plan: whether the class holds the column | | `check` | `cond` | `message` | nothing; a `cond` that is false when cooked is an error stating `message` | | `compare` | `a`, `b` | `op` (`eq neq lt le gt ge`) | a Bool | | `where` | `cond`, `a`, `b` | | `a` where `cond` holds, else `b` | | `pick` | `choice`, `alternatives` | | the alternative the choice names | | `step_sample` | `step`, `value` | | the value of an animated `value` at the step's time | | `step_between` | `step`, `index` | | the fraction (0 to 1) of the step's movement that source `index` of the step has covered; the evaluator defines it | A call that has several outputs names them in refs: `{ kind = "node_output", node, output = "<name>" }`; a node with one output has `output = nil`. ### Refs The v1 refs (`const`, `graph_input`, `node_output`, `list`, `record`, `animated`) and: | ref | stands for | |---|---| | `loop_item { loop }`, `loop_collect { loop, ref }` | the item of a `for` scope, and the list of `ref` over every item | | `fold_value { scope }`, `fold_index { scope }`, `fold_result { scope }` | the value and the index (from 1) of a fold pass, and the value after the last pass | | `fold_before { scope }`, `fold_after { scope }` | the state before and after a pass, inside a fold's `stop` function; `scope` is the `stop` scope | | `step_state { scope }`, `step_index { scope }`, `step_result { scope }` | the state record, the step record (`dt time graphTime index first start`, with `step_sample` and `step_between`), and the state the step reached | | `state { name }`, `clock { field }`, `engine` | declared state, the clock's field, the engine API namespace | | `element { field, class? }` | the element a Field evaluates over: `field = "id"` its index, `field = "P"` its position leaf (no class), else the column `field` of the domain `class` | ### Scopes `graph.scopes[id]` is `{ kind, parent, seq, ... }`: - `for`: `list`, `item`. - `fold`: `count`, `init`, `result`, and `stop` when it states one: `"changed"` (the pass ends the fold when the state it produced equals the one it read) or `{ scope = <id of a stop scope> }`. - `stop`: a scope whose `parent` is its fold. Its nodes read `fold_before` and `fold_after`; `result` is the Bool ref the fold stops on. It is evaluated after each pass. - `step`: `dt`, `substeps`, `result`. The `plain` table of a graph and the `plain = true` flag of an input declaration state which inputs are build-time values. Part of `@builtin::systems.procgen.proc`.

# proc.demos Procedural-generation demo recipes — graph builders that showcase the proc system end to end. Part of `@builtin::systems.procgen.proc`. - **`cashPile(proc, opts?)`** — scatters a billboard source over a disc of points and merges it into a single mesh (the scatter → merge showcase).

# proc.eval Lazy topological evaluator of a graph target, with per-eval memoization and cycle detection. Part of `@builtin::systems.procgen.proc`. ## Graphs built in the call form A graph built with `proc.define(function(g) ... end)` has `surface = "call"`. It records nodes (ops and node assets), scopes (`for`, `fold`, `step`), declared state and the refs between them. It has no output the evaluator is asked for: every node nothing reads is cooked from. ```lua local play = eval.play(graph, { inputs = { count = 8 } }) local report = play:present({ time = 0, frame = 0, fps = 30, duration = 0 }) play:release() ``` `eval.play(graph, opts)` plans the graph, cooks from every node nothing reads and keeps what those nodes return. `play:present(clock)` cooks at a clock (`{ time, frame, fps, duration }`; a `duration` above 0 is a timeline with an end, where a seek replays from the start), `play:setInputs(inputs)` gives the graph other inputs, `play:handle(id)` answers what a node cooked from answered last, `play:report()` says what happened and `play:release()` lets go of everything the play holds, the Handles its output nodes answered included. Every call-form graph cooks through the plan, whoever asks: `proc.eval(graph, target, opts)` of a graph with `surface = "call"` plans it (`opts.inputs`, `opts.clock`), cooks what the plan waits on and then the target through the flat graph, and a node asset used as an op cooks its graph the same way. `output:<name>` names an output of the graph (`flat.outputs` holds each one lowered), and the nodes the eval cooked into its own cache are released apart from what the answer reaches. `eval.plan(graph, opts)` is the plan alone, and `eval.references(graph)` the assets and ops the graph's calls reach, by guid and id, without cooking. ### The document ``` graph.surface "call" graph.nodes[id] { op, inputs = { socket = ref }, params = { name = ref | value }, scope = scopeId? } graph.scopes { [id] = { kind = "for", list = ref } | { kind = "fold", count, init, result } | { kind = "step", dt, substeps, result }, parent = scopeId? } graph.states { [name] = { columns = ref } } graph.inputs { [name] = { type, default, ... } } graph.outputs { [name] = { ref } } -- what a graph used as a node gives ``` `op` is an op id (`"device.kernel"`, or `"op.device.kernel"`), a node asset (`{ __ref = guid, type = "procNode", name }`) or `"construct.<kind>"`. The refs are the v1 refs (`const`, `graph_input`, `node_output`, `list`, `record`, `animated`) and: | ref | stands for | |---|---| | `loop_item { loop }` | the item of the `for` scope in the copy being written out | | `loop_collect { loop, ref }` | the list of `ref` in every copy of the `for` scope | | `loop_index { loop }` | the place (from 1) of the item in the copy being written out | | `loop_carry { loop, carry }` | a value built outside the `for` scope as a pass begins: the value before the loop for the first copy, what the copy before left for every other | | `loop_result { loop, carry }` | the same value after the last copy | | `fold_value { scope }`, `fold_index { scope }` | the value and the index (from 1) of the pass of a fold | | `fold_result { scope }` | the value after the last pass | | `step_state { scope }`, `step_index { scope }` | the state record and the `step` record of a step body | | `step_result { scope }`, `state { name }` | the state the step has reached | | `clock { field }` | `time`, `frame`, `fps`, `duration` or `delta` of the graph's clock | | `engine` | the engine API namespace | ### The plan - A node asset built in the call form is written out where it is called, its inputs bound to what the call was given. A call nothing reads is cooked from through every output it declares. - A `for` body is written out once per item of its list, a `fold` body n times in a chain, a `pick` takes the one alternative its choice names. A copy is keyed by its content, so reordering, inserting or removing items cooks only what is new. - A count or a list a scope needs is a plan value: a constant, an input, or the answer of a node, which the plan cooks and lists in `report.waits`. A column left on the device is not a plan value; reading it back with `transfer.readback` is, and the wait names the readback. The length a scope was written out for is watched: a cook that answers another length plans the graph again. - A `where` whose condition the plan knows takes one alternative. What only the other alternative stands on is not written out, and a call nothing reads that stands on any of it is not written out either (the nodes a node asset leaves unread are written after every alternative of the plan is decided), so nothing reachable only through the untaken alternative is cooked while the plan is made. A node of the graph itself that nothing reads is always cooked. - A `for` scope's `carries` (`{ [id] = { init, result } }`) chain the copies: copy 1 starts a carried value at `init` and copy n+1 at what copy n's `result` lowered to; a `loop_result` read after the loop is what the last copy left. - A step becomes one solver node. Its state is one record of device Columns per play (`g:state(name, { column = { type, count } })` allocates them zeroed). The columns a state allocates are stated through plan values: a literal record, or a record a fold fills or constructs read off a list or an input (per-source columns, counts from `list.count`, names from `geometry.names`), whose counts the plan cooks and lists in `report.waits`. A `member` or `item` read inside the body of a value the plan knows (a count or a list a fold inside the step is written out for) is answered while the plan is made. The step record carries `dt`, `time`, `graphTime`, `index` and `first`. The body runs `substeps` times in each fixed step of `dt` seconds. Pausing holds the state, a seek back replays from the start on a timeline with an end, and a changed value the step reads begins it again. ### A plan is made once A graph is planned once for the values its plan stands on, and every later cook of it reads that plan. - A plan stands on the registry (`registry.revision()`), on the graph its plain inputs build, on the values of the inputs it read (as keys), on the animated values it read at the clock, on the answers it waited on and the nodes it cooked for a count or a list, and on the modules it required (by what their files hold). A cook reads a kept plan after asking each of those again (`expand.stillStands`); a plan that no longer holds is made again, and a plan that does is read. - Each answer and node the plan waited on is held by the key of its cone, without a cook. The leaves a cone stands on are named once, when the plan is kept (`expand.keyWatches`): the graph inputs it reads, the animated values, the constants that hold a device value (a Geometry, a Column) or an asset reference, and the nodes that read live state; the ops, their versions, the plain constants and the wiring are fixed by the plan and the registry. A read asks the evaluator for the key of each leaf as it stands now (`opts._leafKeys`: a device value is keyed by the run it stands on and the writes the run has had, an asset reference by what the asset's files hold) and compares them with the keys the watch stood at. A watch whose leaves are unmoved holds and cooks nothing; a watch whose leaf moved is cooked again, only its cone, and holds when it answers what it answered, and the keys it stands at are renewed. A plan that cooked a node reading the clock, a play's input or a live run, or whose cone stands on a solver or an op that always cooks, is not keyed: each of its watches is cooked again on every read. - A kept plan also holds the answer of each target it was cooked for (up to four a plan, and sixteen plans at a time), filed by the keys of the target's cone: a cook of `proc.eval` that shares no node cache with its caller, finds the cone unmoved and passes no `stats` or `cookRecord` is answered with a copy of the held answer (a Geometry or a Column is cloned, a list or a record of them rebuilt), and cooks nothing. An answer holding anything else (a Handle, a Field) is not held. The held answers are let go of with the plan. - A plan is kept unless it registered a step solver or wrote a run of the device into itself (a `for` over geometries). A plan that stands on a run of the device holds by the key of its cone, and is made again when the key moves. `eval.planCounts()` answers how many plans were made and read, the milliseconds each took, `notKept`, the plans that could not be kept by what stood in the way, `served`, the cooks answered from a held answer, and `notKeyed`, the kept plans whose watches are cooked again on every read, by why. - `engine` is the engine namespace, a constant. A member read or an item read out of constants, out of a record or a list a call wrote, is the ref written there and costs no node; `engine.require` of a module named by a constant is the module, required while the plan is made and asked for again each time the plan is read. - The plan is made in slices of `budgetMs` (5 ms) when the caller can yield; a cook over the plan hands a frame back after `cookBudgetMs` (100 ms). - A cook that shares no node cache with its caller keeps none: nothing is keyed or filed, what the plan cooked while it was made (or asked again) and what the cook makes stand in one table by node, and all of it is released as the cook ends but what the answer reaches. A Field that is the answer keeps the runs its leaves read; they stand as long as it does. - A node of a plan that stands is held to the contexts its producers operate in once, takes the label of its refusals from one string, and takes its params prepared once when every one is a constant. ### A cook after a change is run from a list (`cookrun`) A kept plan whose cone stands on numbers (graph inputs holding a number or a Bool) is cooked node by node while those numbers move. The recording wraps the plan's cone re-check and the cook together: the first such cook after the plan was made is recorded as a compute list and the next one is recorded beside it; the words that differ between the two recordings (a dispatch param, a word of a write) must each be the value of one leaf in both, and become the slots of the second list. A cook after that runs the list with the leaves' values in its slots, asks the recorded plan-time read-backs again, runs the watches that are not nodes (modules, animated values, the registry stamp) and answers a device copy of the list's columns (`cookrun.counts()`: `recorded`, `diffed`, `replayed`, `verified`, `mismatched`, `readbackChecks`, `dispatches`, `refused` by why): no node is cooked and no buffer is allocated but the copy. What makes a recording stand, and what ends it: - Two recordings are one cook when they make the same dispatches over the same programs and workgroups, bind buffers one for one, and write the same number of words; a run placed at another offset (`zero_base_*`, a write offset) is a placement. A first cook that uploads a mirror of a CPU column makes the pair differ once, so the comparison is tried again on the next cook (twice at most). A moved leaf that is no word of the list is refused by name, since its value reaches the device by a write the recording did not hear. - A cook that read the clock, a play's input or a live run, and an answer that cannot be copied are not recorded. - A `cpu.call` is first handed the geometries it is given with their columns on the device standing in as columns that answer their type, width, length and run (`substrate.structureOf`): a call that asks for no numbers (the names of the columns a class holds, the types a join decides) moves nothing off the device and records no read-back. A call that asks a stand-in for its numbers, fails, answers a stand-in, declares a return that is no plain value, or is handed a geometry counted on the device or a part is made again over the drained inputs, and its read-back is recorded. - Every node whose cook read back from the device (`transfer.readback`, a drained `cpu.call`) is recorded as a read-back row: its inputs, whether they were drained, and a digest of its plain outputs. After the list has run each row is asked again; one that answers another value than it did ends the recording and the cook is made node by node, answering correctly. A read-back whose outputs are not plain data is not recorded. - The first replay of a list is held to the cook of the same values made node by node, column for column; a difference ends the recording (`mismatched`). - A changed key of any other leaf (a Geometry input, a constant device value, an animated value), a plan made again and a registry change let go of the recordings; at most six plans hold recordings. - The recordings of two threads do not meet: a dispatch and a write belong to the recording of the thread that made it. - An answer a recording makes is copied word for word onto runs of their own (`cookrun.deviceCopy`) for the caller and for the held answer, so the buffers the list writes in place are never shared. `cookrun.setEnabled(false)` cooks every cook node by node. A `g:fold` of three passes or more over device state is planned as one `construct.fold_run` node (`foldrun`): the body is built once as a flat graph with the inputs `state` and `index`, the first pass is cooked while a compute list records it, and every later pass queues that list over a copy of the state, so a pass after the first cooks no node. `foldrun.counts()` answers how many passes were recorded, replayed and cooked, and how often a body was refused a list, by why. A body cooks each pass on its own when it reads `index`, when the state holds something the list cannot follow (a record, a text, a readback), when a pass makes a state of another shape, or when the fold sits inside another recording. `foldrun.setEnabled(false)` writes the folds of the plans made after out once per pass. ### How a step runs A step solver plans its body once (`proc.eval.stepplan`), when the state takes its first step. - A node of the body that depends on neither the state, the `step` record, an animated value nor the scene is STATIC: it is cooked once, with the first step, and read as it stands by every later step (`opts.fixed` of the evaluator). The plan reads only the nodes the next state stands on. - What is left is the device work of a step. The first step of each distinct set of `step` values the body reads (its `dt`, `first`, `progress`, ..., and the animated values it reads, as the device sees them: the f32 they round to) is cooked with every dispatch and every write it makes into a device buffer kept as one compute list over buffers the solver holds, and the next state written back into the state's own columns by the last dispatches of the list. Every later step with those values queues the list: the dispatches read the state's columns where they stand and write the next state into them. A step that runs from a list cooks no node and allocates no buffer. - The columns of the state are written in place, so what a step presents is a copy of them made on the device. - Up to six sets of `step` values are kept. A body the plan cannot stand on is cooked a step at a time with its static nodes still read as they stand, and says why in `report.steps[<step id>].reason`: a node of the body reads the clock, a play's input, a live run or the scene; the body reads values back from the device to the CPU; the next state is not a record of Columns the state's own shape; or a `step` value the body reads takes a new value in more than six steps (a body that adds `step.time` to a column, say). - `play:report().steps[<step id>]` holds `steps`, `replays`, `recorded`, `interpreted` (steps cooked node by node), `plannedDispatches` (what one list queues), `dispatches` (queued in all), `allocations` and `uploads` (buffers made and uploads done by steps), `ops` (nodes cooked in steps, by op), `staticNodes`, `variants`, `mode` (`replay` or `cook`), `reason` and `keyValues` (the `step` values of the last step). - `stepplan.setPlanning(false)` makes the solvers begun after cook every step node by node, which is how a planned body is held to the numbers a cooked one gives. A state column the next state names as a Field, a number or a vector is evaluated into a column of the state's own length and type. ### Constructs A construct is a node the evaluator itself knows: `construct.member`, `construct.item`, `construct.member_set`, `construct.column`, `construct.column_set`, `construct.column_remove` and `construct.engine` and `construct.select` are cooked; `construct.pick`, `construct.compare` and `construct.where` are written out in the plan (a compare of two constants is their answer, a `compare` otherwise calls the `math.compare` node, and a `where` over a condition the plan does not know is a `construct.select` node). `construct.select` chooses `a` where `cond` holds and `b` where it does not: numbers, vectors and Fields element by element (`math.where`), and a Geometry, a record or a text by a condition that is one value, which a condition over the elements of a column is not (it is refused naming `g.pick`). A Column or a Geometry a construct reads from a record or a list is a clone of it. `construct.member` reads `count` and `keys` of a plain list or record (the number of members, the sorted names of a record or the places of a list; a value that is nothing has none), `count`, `type` and `lanes` of a Field (the length of the longest column its chain reads, its element type, its components; a Field that reads no column has no length, and the read refuses naming `geometry.point.count`, `column.count` and `g.field.index({ domain })`), and `count`, `type` and `lanes` of a Column. `construct.member` also reads `x`, `y`, `z` and `w` of a vector (a Field of that component for a Field, a Column of that component for a Column of Vec2, Vec3, Vec4 or Quat), the classes of a Geometry, its `material` and its `names` (the attribute names each class holds). On a class of a Geometry a read of a `detail` column answers the value the detail holds. `count` of a Column or of a class of a Geometry is the live count when the elements are an appended or compacted output (a Column of one word, which a kernel with a `domain_count` binding reads the live count through, and a kernel without one runs over the capacity); `capacity` of either is the number of elements the run is allocated for. A record a graph holds under a name a class goes by (`point`, `vertex`, ...) is read and written as a record: `x.point.name` is the member of the member. `construct.column`, `construct.column_set` and `construct.column_remove` take `edge` beside `point`, `vertex`, `primitive` and `detail`: an edge is a unique point pair of the primitives, so the class counts them and a column written on it is one value per edge. `count_set` takes the four stored classes. `construct.column_set` writes a Column, a Field evaluated over the class it is written into, a vector or a number, a record or a text (one value for every element, a constant Record or String column) or a list of records or texts (one to an element, held in a Record or String column on the CPU); a record whose fields are numbers is a record, and a list of numbers is a vector. A column that is the structure of a geometry (`point.id`, `vertex.pt`, `primitive.vstart`, `vcount`, `curve` and `closed`) holds whole numbers: a number, a Field or a Column written to it is stored as an Int, and so is a value written to a column that already holds Int. A detail value is held as itself, a record among them, and `construct.column_remove` removes it. The inputs of every construct take nothing as a value: an optional input a call left out reaches them as nothing. `construct.scene { what }` answers where the graph stands in the scene it is cooked in (`entity`, `placement`, `inverse`, `rotation`); it is read as `g.clock.placement` and the other names, and as `g.transform`. ### What the plan answers A construct that answers while the plan is made cooks the nodes it reads (a wait in `report.waits`, a readback named as one) and records the answer, which is what the play compares to decide whether the plan still stands. - `check { cond } message`: a condition that is false refuses the play with the message. - `has { geometry, class, name }` is the Bool of whether the class holds the column; `names { geometry, class }` is the list of attribute names the class holds. A `for` over the names has one copy per name. - `fold` with `stop`: after each pass but the last the stop is answered, and the fold ends at the first pass whose stop holds. `"changed"` holds when the pass left its state as it found it (numbers by value, a Column or a Geometry by what its runs hold: a device run read for the comparison is a readback wait). A stop function's scope reads `fold_before` and `fold_after` and its result is the Bool. The report's fold scope states `copies`, `stop` (`"changed"` or `"function"`) and `stopped`; each answer is a wait named "the stop of fold '<id>' after pass <n>". - A node asset called with plain inputs (an input with options, or of type Bool or String) is the graph its source builds for those values (`builder.forInputs`); a play built for other plain inputs plans again. Constructs cooked as nodes: - `count_set { geometry, class, count }`: the geometry with the class's element count set. A number sets it; a live count Column (an appended output's) becomes the live count over the capacity it carries; arithmetic over a live count (`kept.indices_count * 6`, a Field over live counts) is evaluated on the device as one word, and the class is as large as that arithmetic reaches when every count it reads is full (`substrate.atCapacity`). - `material_set { geometry, material }`: the geometry carrying the material (a Material value, an asset reference or a name; nothing for none). - `step_between { step, index }`: how far from 0 to 1 the step has come through the span of graph time the present covers; `step_sample { step, value }` is the value, which a step body samples at the step's time. The step record carries `dt`, `time`, `graphTime`, `index`, `first`, `start` (the time the step began at) and `progress`. An `element` ref is the Field the graph's `g.element` stands for: `id` and `P` are fields the field compiler fuses into the chain they sit in; a column of the evaluation domain is `fieldc.element(field, class)`. ### Cooking Every play cooks into one store of the world, filed by content key (the op, its version, the seed, the params and the keys of the inputs): a node of any graph that cooks the same op over the same inputs is cooked once. A value that holds an asset reference is keyed by what the asset's files hold, so editing a module a node calls cooks the node again. The nodes a play pulls from and every step are the play's own. An output node answers a Handle (a table with a `release` function). `cpu.call` owns its list of results: a Handle in it is released when the cook is superseded and when the play ends.

# fieldc A Field is a per-element expression. `fieldc` holds what a Field is made of and how it runs: a chain of templates over a position leaf, an element number, column reads and numbers is written as one WGSL function and runs as ONE dispatch of `kernels/map`, wherever it is consumed. Nothing dispatches per operator. ## Where a Field is evaluated ```luau local column = fieldc.evaluate(field, domain, opts) ``` The one entry point a consumer of a Field calls (a kernel's input, an attribute write, an output): `device.kernel` for a Field bound to a column input, `attribute.write` for a Field value, and every other node that needs a Column. - `field`: a Field, a Column, a `BufferRef` (a device column handed through `cpu.call`), a number or a vector record. - `domain`: a number of elements, or a Geometry (its `opts.class` elements, points by default), whose attributes the leaves reading the evaluation domain bind. - `opts`: `{ class, count, type, clock, where, label }`. `type = "Int"` writes i32 words (a Field tagged Int does so by default). `clock` is `{ time, frame, fps, duration }`: animated values are first sampled there. `where` names the caller in a refusal. - Answers a Column of the domain's count. Raises, naming what refused, when the chain cannot be written as a function. A chain holding an animated value or a live run answers a live column. `fieldc.liveRuns` finds it and `fieldc.tick(runs, clock)` rewrites it each frame: the animated values are sampled at the clock and written into the numbers the dispatch reads, and the dispatch runs again into the same run. An animated input therefore changes the result every frame without a cook. ## Fields the nodes make | Construct | Module | Answers | |---|---|---| | `fieldc.field(v)` | `fieldc` | any socket value as a Field: Field, Column, BufferRef, number, vector, animated value | | `operators.apply(name, ...)` | `fieldc.operators` | `math.*`: the plain result over numbers and vectors, a Field over a run or a Field | | `fieldc.element(name, class?, width?)` | `fieldc` | what `g.element` stands for: `"id"`, `"P"`, or a column of the domain (`g.element.point.N` is `element("N", "point")`) | | `leaves.elementId()` | `fieldc.leaves` | the element number, an Int Field (`g.element.id`) | | `fieldc.position` | `fieldc` | the position leaf `p` (`g.element.P`) | | `leaves.context(class, name, width?)` | `fieldc.leaves` | an attribute of the evaluation domain | | `leaves.rand(seed, scope, id)` | `fieldc.leaves` | the unit draw, equal to `hash.unitFloat` to the bit | | `leaves.call(fn, args)` | `fieldc.leaves` | a function of a prelude shader module of `kernels/` | | `leaves.gather(column, index)` | `fieldc.leaves` | a run read at computed elements | | `leaves.substitute(field, position)` | `fieldc.leaves` | the chain read at another point (`fieldc.withPosition`) | | `leaves.index(domain)` | `fieldc.leaves` | an Int column of 0 to n - 1 | A Field made by these answers `f.x`, `f.y`, `f.z`, `f.w` as the Field of that component. Components are Fields, so the Field of a vector is built from them with `operators.vec2`, `operators.vec3` or `operators.vec4`; Luau's `vector.create` takes numbers. ## How the leaves reach the kernel A chain's leaves are columns. `kernels/map` states every leaf's shape in its `cols` table and reads up to as many leaves as one dispatch has storage buffers for (`compute_abi.directLimit`: 8 per stage on every target, less the table, the numbers and the output, so 5 for `map`) straight from the buffer of the leaf's own run, at no cost beyond the binding. A chain of up to 5 leaf columns is the one dispatch of `map` and nothing else. Leaves past those are copied into the table, one copy dispatch each. `fieldc.bindSpec(spec, { direct })` makes the table; `direct` is the list of leaf slots read from their own runs (`compute_abi.directPlan(columns, limit)`), and the variant is made with the same list: `program:variant({ specialize = ..., direct = { cols = direct } })`. Without `direct` every leaf is copied into the table. `fieldc.operators` folds numbers: every operand a number or vector gives a number or vector. A narrower operand widens to the widest (a number applies to every component, a shorter vector reads 0 where it has none). Division and remainder by 0, the square root and the logarithm of a value at or below 0 answer 0. ## The walk step contract (for `kernels/walk`) A walk kernel takes its per-walker function as a Field spec, the way `kernels/map` takes `TEMPLATE`. ```luau local spec = fieldc.walkSpec(step, { width = 2, count = walkers, done = stop }) -- a state of 8 floats: lanes 0 to 3 in `step`, lanes 4 to 7 in `high` local wide = fieldc.walkSpec(low, { width = 8, count = walkers, high = high }) local bound = fieldc.bindSpec(spec) -- specialize = spec.specialize; bind cols = bound.cols:buffer(), u = bound.u ``` - `width`: floats per state, 1 to 8. `step` is the next state's lanes 0 to 3, a Field of `min(width, 4)` components; above 4, `opts.high` is the Field of the `width - 4` components of lanes 4 to 7. - The state is read through `fieldc.walkState(count, first?)`: `count` (1 to 4) lanes from lane `first` (default 0), all inside lanes 0 to 3 or all inside lanes 4 to 7. A state of 8 floats is read as two leaves, `walkState(4, 0)` and `walkState(4, 4)`. The nodes `field.walk_state({ count, first })` and `field.walk_index()` are these leaves in a graph. - `step` and `high` are written over the state leaves, `fieldc.walkIndex()` (the step number k, from 0), `leaves.elementId()` (the walker's number), Column reads (one value per walker, or a gather at a computed index) and numbers. - `opts.done`: an optional Field<Float> over the same leaves; the walker stops before step k when it is not 0. - `spec.specialize` is a table of the specialization values the walk kernel takes, ready to hand to `device.kernel` / `program:variant` as its `specialize` value: `WALK_STEP` (`zero_walk_chain_step(s, s_hi, k, id)`), `WALK_STEP_HI` (`zero_walk_chain_step_hi(s, s_hi, k, id)`, or `s_hi` when `width` is 4 or less), `WALK_DONE` (`zero_walk_chain_done(s, s_hi, k, id)`, or `false` when there is no `done`) and `WALK_PRELUDE`, the module-scope WGSL that defines those functions, preceded by the preludes the chain calls. Lanes 0 to `width - 1` of `s` (lanes 0 to 3) and `s_hi` (lanes 4 to 7) are the state. - The functions read its leaves through a `cols` columns binding (`cols_f32(slot, i, 0u)`, `cols_vec3(slot, i)`, `cols_i32` for Int runs) and its numbers through `u_get(k)`: the kernel declares those two bindings exactly as `kernels/map` does. `fieldc.bindSpec(spec)` answers the table (`cols`) and the numbers buffer (`u`) to bind; `release()` lets both go. - A read past a run's end reads its last element. ## Other entry points `fieldc.mapSpec(chain, count, domain, { position })` writes a chain as one function for `kernels/map` and `fieldc.runMap(spec)` runs it. `fieldc.compile` / `fieldc.column` write the same chain as a kernel of its own; they stay for the consumers that bind buffers directly.

# proc.fields Value wrappers for the procedural-generation type system: `Field<T>`, `PointCloud` and `Population`. Part of `@builtin::systems.procgen.proc`. Typed values backed by plain strided Luau arrays. - **`Field<T>`** — a lazy per-element value. `Field.constant(t, values)`, `Field.fn(t, stride, f)`, `Field.buffer(t, stride, buf)`; `:sample(id)` → the `stride` components, `:materialize(count)` → a flat `count*stride` array. - **`PointCloud`** — the value a `.procNode` input declared `PointCloud` receives (`proc.substrate.toPointCloud`); every other input, and every op, takes points as a `Geometry` (`proc.geometry.new`). `PointCloud.new(positions)` (flat stride-3 array); `:count()`, `:position(id)`, `:setAttribute(name, field)` / `:getAttribute(name)` / `:attributeNames()`. - **`Field.transform(offset, orient, scale)`** — a per-element transform whose three parts are fields of their own, so each compiles to the device; `:transformParts()` hands them back. Every value carries a `__proc_type` tag that `proc.types.typeOf` reads (`"Field<Vec3>"`, `"PointCloud"`, `"Population"`).

# proc.geometry CPU geometry container (positions/indices/normals/uvs) + bounds, normal recompute, and renderer.mesh.create args. Part of `@builtin::systems.procgen.proc`.

# proc.graph The graph data model and its definition entry: the nodes a graph holds, the normalized `InputRef` edges between them, its inputs and outputs, and its JSON (de)serialization. `proc.graph.define(function(g) ... end)` builds a graph in the call form, whose authoring surface is `proc.builder`: nodes called by asset identity (`g.points.disc({ ... })`), inputs typed by their defaults (`g:input`), sockets that take Luau's operators, members, columns and `for`, and the declarations a graph states about itself: `g:describe` (what it makes), `g:output` (what it gives), `g:family`, `g:timeline`, `g:still` and `g:cost`. The result is a graph with `surface = "call"` that records each node by the guid of the asset it calls. `proc.graph.refusedInput(graph, name, value)` names why a value is not one an input holds. `proc.graph.fromJSON` reads a graph document back and `toJSON` writes it. Part of `@builtin::systems.procgen.proc`.

# proc.hash Deterministic, portable scoped hashing for the procgen evaluator. `scoped(seed, graphId, compositePath, nodeId, channel, elementId) -> number` folds its arguments with 32-bit FNV-1a (via an exact 16-bit-split `mul32`) and a final avalanche, producing a bit-identical `u32` on native, WASM, and Android. `unitFloat(...)` maps the same scope to a value in `[0, 1)` for deterministic random draws. No `math.random` / `os.time` / float transcendentals — determinism is the contract. The per-element scope (`elementId`) keeps a given element's draw stable as unrelated element counts grow.

# proc.noise Deterministic, portable value/gradient noise. Part of `@builtin::systems.procgen.proc`. Built on the integer-lattice hash in `proc.hash` (`latticeCell2/3` / `unitCell2/3` — the corner hashes of one cell, each bit-identical to the matching `hashInts` call): every lattice corner's random value/gradient is integer-derived, and the only continuous math is the quintic fade + linear interpolation. No float transcendentals and no `math.random`, so the result is bit-identical on native, WASM, and Android — which is what makes a procedural texture reproducible everywhere. Exposes `value2`/`value3`, `gradient2`/`gradient3`, and `fbm`.

# proc.ops Op-family loader: registers every procedural op against the registry. Part of `@builtin::systems.procgen.proc`.

# proc.parity The machinery behind the procgen rewrite's parity harness (`procgenParity`), its sheet tests (`procgenSheet`) and the `procgen.coverage` tool. - `parity.json`: `entries` holds one entry per current op. Each names its new composition (`new`, node ids as `nodebox.name`, or `nodebox.*` for any node of a nodebox), its class (`exact`, `meaning` with an `invariant`, `gone` for a named decision with a `note`, `unmapped` where the sheet names no counterpart), and `tolerance` the comparison reads. An entry that states `decided` (the text of the ruling that accepts the difference between the op and its node) keeps running: the value differences its comparison finds are reported as accepted, under the verdict `decided`, and are held to nothing, while a node that raises and the cost findings stay findings (`accepting`, `decidedLines`). `budgets` states, per op, the read-backs its node may make (`{ "<op>": { "readbacks": n } }`); an op without one may make as many as the current op does. `types` maps a socket's type to the fixture a case builds for it. `cases` holds a case per op that needs more than the defaults and names only content the library ships. A parity suite states the cases whose inputs are its test fixtures in the `cases.json` of its folder (`{ "cases": { "<op>": case } }`), since the library ships its test content nowhere; `cases()` is both together, one case per op, and an engine whose library leaves the suite out finds no case for those ops. - A case states `params`, `fixtures` (a fixture by input socket), `node` (the new node a multi-node entry compares against), `rename` (`inputs`, `params`, `outputs`: the new node's names where they differ, `false` leaves a name out), `compare` (`bounds`: a Geometry is held to its bounds alone, for an output whose element layout differs by design; `ramp`: two ramps are held to the values they read at the same positions), `sink` (`asset` or `handles`: the op writes to the world, each side under its own name and what it wrote is compared and removed), `world` (entities spawned for the run; `scene` takes the run's root scene, `settle` waits until the op runs on them), `tolerance` (bounds that replace the global ones for this case, `{ attribute = 0.05 }`: for an op whose values come from the device's sampler, whose fixed-point weights and decode answer within a fraction of a percent of the exact blend a node computes), `ignore` (outputs left out), `unreachable` (the sentence that says why the harness has no fixture for the case; the entry then counts as a harness error) and, for an op that is a solver over a timeline, `suite` and `describe` (the group of an existing suite that holds its comparison; `deferred` leaves that group to the suite's own run and states the entry pending, for a group that costs the suite's whole time a second time inside this one). - A fixture is a name (`mesh`, `points`, `curve`, `positionField`, or a type named in `types`), a current op run on its own fixtures (`{ op, params, inputs, output }`; the new side builds it through the node that replaces the op when the entry for that op names exactly one, so a ramp, a group, a prefab, a raster or an Sdf a node reads is one that library made; `shared: true` makes both sides take what the current op makes, for inputs the entry under test is held to and the op that made them is not), a node run on its own fixtures (`{ node, params, inputs, output }`, a new node by id), a list (`{ list }`), a record (`{ record }`) or a literal (`{ value }`). A case's `newInputs` are fixtures only the new side takes, for an input the current op states as a param (a texture the node reads where the op names the asset). - `sheet.json`: the composition sheet's expectations: the four ops, the 23 kernel families with their tallies (a kernel asset `<kernel>_<pass>` belongs to the family `<kernel>`), the layers, the L2 ids as the core package names them, `universalUses` (the L2 nodes every row may call), one row per node family (the kernel families, L2 nodes and ops a node of the row may name; `authorKernel` for rows whose nodes run a kernel the author names; which nodes may stand on one kernel family alone), and the reported numbers. `scan()` finds the new parts in the library: the nodes of every built-in nodebox wherever its package keeps it, the kernel families with their pass assets, and the modules that sit beside nodes. `analyze(src, ...)` reads a node's source: the nodes it calls (`g.<name>(...)`), the ops it names (`op.<name>`), the kernel families it names, a structural hash per call, and WGSL text in its strings. `rowViolations(scan, node)`, `dispatchViolations(scan, node)` and `directCallers(scan)` state what a node breaks of the sheet. `valuesHold(result)` reads a comparison's values alone, which is what lets an existing suite run on the nodes of an op whose cost is over. `assess(scan, entry)` states where an entry stands (`decided`, `unmapped`, `pending`, `ready`); `compare(scan, entry)` runs a ready entry's current op beside its node; `checkCase(entry)` runs the current op on the entry's case. `redirect(map, fn)` runs `fn` with `registry.get` answering a new node for each op id in `map`; `runSuite(name, redirect)` runs an existing suite's cases through the test framework's own runner, and `runSuiteOnNodes(scan, name, ops)` runs it as it stands and with its ops answered by their new nodes. `report(opts)` is the coverage report. A comparison states cost as separate numbers (`result.cost`): `oldMs` (the current op's CPU time), `planMs` (the evaluation outside the nodes' own cooks: expanding the call form, lowering refs and constructs, scheduling, with the plan's share of the waiting taken out), `cookMs` (the CPU time the nodes' cooks spend, with their share of the waiting taken out), `waitMs` (the time in `task.wait`, a read-back's frames, shared between the cooks and the plan by the read-backs each made), `dispatches` (device dispatches queued), `readbacks` (read-backs the substrate counted) and `frames` (frames that passed during the evaluation). A Field in an output is read over the Geometry its side was given, a Column by its values, and a Bool answers 1 or 0. The cost ratio of `tolerance` is applied to `cookMs` against `oldMs`; the read-back count is asserted against the op's budget on its own, so a read-back removed from a node shows as `frames` falling to zero. Times are the median of three runs; counts are the last run's. A comparison states its values and its cost apart. `result.valueFindings` are the differences in what the node answers and `result.costFindings` the cost and read-back findings (`result.findings` holds both). `verdict(assessed, result)` reads them as `value` (`equal`, `differ`, `missing` for an attribute, layer or column the new output lacks, `raised` for a node that failed on the case's inputs, `harness` for a case whose inputs could not be made, `skipped`, `decided`) and `cost` (`within`, `over`, `none`); `summary(scan)` counts every entry under exactly one of `pass`, `costOver`, `differ`, `missing`, `raised`, `harness`, `skipped` and `decided` and reports the same per family (the nodebox of the entry's first new node) with the median and worst cost ratio. What is compared where the two libraries carry a value differently: a Geometry by its live counts (a domain allocated at a capacity compares its live front), a Raster layer by layer at the grid's cell centres, a Texture by size, channel count and texels (bytes scaled to 0 to 1 and held to half a byte step), a count the new library holds on the device as a one-word column by its value, a Population against the instanced points by instance count, and a list of numbers against a list of records of numbers as one layout finding that says whether the numbers agree.

# proc.placement Where a graph stands in the world, as a 4x4 matrix held as 16 numbers column after column: the layout `entity:worldMatrix()` and `camera.viewData().viewProj` answer in. A graph is evaluated in its own space, whose origin is the entity it stands on. A Generator draws what it makes under its entity, so the graph's origin stands where the entity does, and an effect built at the origin works wherever it is played. A node that pulls from the scene (`scene.fetch`, `terrain.ground`, `sim.scene_colliders`) reads that origin from the scene the evaluation hands it, `ctx:scene().origin()`, and takes what it reads from the world into the graph's space. A graph evaluated standing on no entity has the world's origin for its own (`proc.placement.IDENTITY`). `mul`, `inverse`, `point`, `scale`, `rotation`, `turn` and `conjugate` are the matrix and quaternion steps such a node takes.