# 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**.

# postReference_focusBars Four rows of bar pairs, 8 pairs across the top row and doubling on each row below: the focus chart a depth-of-field reading is taken off. Drawn unlit by `@builtin::shaders.referenceChart`, so a picture of it is measured against the light its properties state. Part of the post-verification reference scenes (`@builtin::scenes.postReference.*`); `@builtin::modules.postMetrics` reads them.

# postReference_skyRamp A sky-blue ramp of light from 0.02 to 0.6 across: a clear sky's gradient. Drawn unlit by `@builtin::shaders.referenceChart`, so a picture of it is measured against the light its properties state. Part of the post-verification reference scenes (`@builtin::scenes.postReference.*`); `@builtin::modules.postMetrics` reads them.

# proc.ops.instances Instancing ops. A population is points carrying a `Mesh`: `instances.on_points` stands a source on every point (as each point's `Mesh`, with the source's material as `Material`), placed by `P`, `orient` and `scale`; `instances.pick_random` and `instances.pick_by_attribute` stand one of several sources on each point, `Mesh` holding its index into the sources the detail's `labels.Mesh` lists. `instances.randomize_transform` computes a per-instance transform on the device, `instances.transform`, `instances.cull` and `instances.set_material` work on the points' columns on the device, and `instances.realize` stamps the population into a single merged Geometry on the device (`proc.substrate` `Geometry.copyToPoints`), every other point attribute standing on its copy's points. A Generator draws a population as one instanced draw per source, placed on the device. Part of `@builtin::systems.procgen.proc`. `instances.draw` registers one hardware-instanced draw per source variant, drawing matrices it composed on the device (several sources: each variant's points gathered there, its rows past them empty), and gives each the material its own source names — the op's `material` param first (the whole-population override), then the variant's source Geometry's `.material`, then the population's `Material`, then the default. A source carrying an in-memory `Material` value is filed as a runtime material for the live draw and realized to its own `.material` by `population.write`.

# Chrome A polished chrome surface built on the `pbr` shader — fully metallic (`metallic: 1.0`) with a bright near-white base colour (`0.95, 0.95, 0.97`) and very low roughness (`0.05`) for mirror-sharp reflections. Opaque, back-face culled, instanced, with the `_METALLICSPECGLOSSMAP` keyword enabled. ## Inputs - `colors.base_color` (`0.95, 0.95, 0.97, 1.0`) — bright, faintly cool chrome tint. - `floats.metallic` (`1.0`) — fully metallic. - `floats.roughness` (`0.05`) — near-mirror sharpness. - `textures.base_color_texture` (`default:white`): the white base texture the colour multiplies against, so the surface renders `base_color` alone.

# Snow Particle A soft, cold-white flake surface for falling-snow particle effects — a near-white base colour (`0.95, 0.97, 1.0`) with a cool blue-grey emissive glow (`0.25, 0.3, 0.4`) so flakes stay faintly visible in shadow. Transparent, double-sided (`cull: none`), and drawn in the transparent queue (`3000`). Built on `@builtin::shaders.snow_material`. ## Inputs - `colors.base_color` — the cold-white flake tint. - `colors.emissive` (`0.25, 0.3, 0.4`) — cool self-illumination that keeps flakes readable in dark scenes. - `floats.roughness` (`0.8`) — matte, non-glossy flakes. - `floats.metallic` (`0.0`) — fully dielectric.

# Gold Polished gold — a fully metallic PBR surface with a warm yellow base colour (`1.0, 0.84, 0.0`) and low roughness (`0.25`) for bright, sharp reflections. Built on `@builtin::shaders.pbr`. ## Inputs - `colors.base_color` — the gold tint. - `floats.metallic` (`1.0`) — fully metallic. - `floats.roughness` (`0.25`) — sharpness of the reflection; raise for a brushed look.

# Checkerboard A procedural checkerboard pattern rendered by `@builtin::shaders.checkerboard`, alternating a red base colour (`1.0, 0.2, 0.2`) with a blue emissive colour (`0.2, 0.2, 1.0`). Opaque and non-metallic (`metallic 0.0`) at mid roughness (`0.5`) — useful as a UV / scale test surface. ## Inputs - `colors.base_color` — the red square colour. - `colors.dark_color` — the blue square colour. - `floats.roughness` (`0.5`) — diffuse spread on the lit squares. - `floats.metallic` (`0.0`) — dielectric surface.

# Custom Textured A textured opaque surface built on `@builtin::shaders.custom_material`, sampling the `array_texture` builtin over a warm peach base colour (`1.0, 0.8, 0.6`). Non-metallic (`metallic 0.0`) at mid roughness (`0.5`) — a worked example of pairing a custom shader with an array texture. ## Inputs - `textures.base_color_texture` (`@builtin/textures/array_texture`) — the sampled array texture. - `colors.base_color`: the warm peach colour the texture is multiplied by. - `floats.roughness` (`0.5`) — diffuse spread. - `floats.metallic` (`0.0`) — dielectric surface.

# Sky Procedural A fully procedural atmospheric sky with a day/night cycle, built on `@builtin::shaders.procedural_sky`. Renders with no culling and no depth write behind all geometry (queue `1000`), computing gradient, sun, moon and stars analytically from its parameters — no texture required. ## Inputs - `properties.zenith_color` / `horizon_color` / `ground_color` — the atmospheric gradient from overhead (`0.1, 0.3, 0.6`) through the horizon (`0.5, 0.7, 1.0`) to the ground (`0.3, 0.25, 0.2`). - `properties.sun_intensity` (`20`) / `sun_size` (`0.02`) — brightness and disc size of the sun. - `properties.turbidity` (`4`) — atmospheric haze / scattering density. - `properties.stars_intensity` (`1`) / `moon_size` (`0.03`) — night-sky star brightness and moon disc size.

# Sky Cubemap A cubemap sky/environment background built on `@builtin::shaders.cubemap_sky`. Renders with no culling and no depth write behind all geometry (queue `1000`), sampling the built-in `Ryfjallet_cubemap` with adjustable rotation and exposure. ## Inputs - `textures.sky_texture` — the cubemap sampled as the sky (`Ryfjallet_cubemap`). - `floats.rotation` (`0.0`) — yaw rotation of the sky around the vertical axis. - `floats.exposure` (`1.0`) — brightness multiplier applied to the sampled colour.

# Default Unlit A flat, unlit surface that renders its base colour directly with no lighting response, built on the `unlit` shader. Uses a white base colour (`1.0, 1.0, 1.0`) over the `default:white` texture with `emissive` (`1.0`) for full brightness — the go-to default for UI, gizmos, and debug geometry that must stay legible regardless of scene lighting. ## Inputs - `colors.base_color` — the flat colour shown directly. - `textures.base_color_texture` (`default:white`) — the white base texture the colour multiplies against. - `floats.emissive` (`1.0`) — full, lighting-independent brightness.

# proc.registry The operation registry: register/lookup/schema/search/help for procedural ops. Part of `@builtin::systems.procgen.proc`.

# Emissive White A bright white light-emitting PBR surface built on the `pbr` shader with the `_EMISSION` keyword enabled. A white base colour (`1.0, 1.0, 1.0`) paired with a strong `emissive` (`20.0`) makes it glow and drive bloom — well suited to light fixtures, emitters, and glowing accents. Non-metallic (`metallic 0.0`) at mid roughness (`0.5`). ## Inputs - `floats.emissive` (`20.0`) — high emission strength that produces the glow. - `keywords: _EMISSION` — enables the emissive path in the PBR shader. - `colors.base_color` — the white surface and emission colour. - `floats.roughness` (`0.5`) — diffuse spread on the lit surface.

# Water An animated water surface with a deep blue base colour (`0.1, 0.3, 0.8`) and low roughness (`0.2`) for glossy, reflective highlights, driven by a scrolling normal map for wave detail. Opaque, back-face culled, instanced, in the opaque queue (`2000`). Built on `@builtin::shaders.water_material`, sampling `@builtin/textures/water_normals`. ## Inputs - `colors.base_color` (`0.1, 0.3, 0.8`) — the water body colour. - `floats.roughness` (`0.2`) — low roughness for sharp specular reflections. - `floats.metallic` (`0.0`) — dielectric surface. - `textures.normal_texture` — the wave normal map (`@builtin/textures/water_normals`).

# postReference_chrome A polished metal: its highlight of a bright light is a sub-pixel specular, the firefly a bloom and a temporal resolve are read on in the post-verification reference scenes.

# Grass blades Swaying grass for a blade mesh, built on `@builtin::shaders.grass_material` with the same green as `@builtin::materials.grass` (`0.22, 0.62, 0.16`) and `sway` at `1.0`. The shader bends each vertex along its blade in proportion to `uv.y²`, so this material belongs on a mesh whose `uv.y` runs 0 at a blade's root to 1 at its tip — a merged field of blades, each a cross of two tapered quads. It inherits the Rust-side render defaults (opaque, back-face culled, queue `2000`) so its pipeline matches the library variant compiled at startup. ## Inputs - `colors.base_color` (`0.22, 0.62, 0.16, 1.0`) — the grass green tint. - `floats.sway` (`1.0`) — the full blade bend. `@builtin::materials.grass` leaves it at the shader's default of `0` for a ground surface.

# Text Default The default surface for Text3D — a white base colour (`1.0, 1.0, 1.0`) drawn with alpha blending and no depth write so glyphs composite cleanly over the scene. Transparent, double-sided (`cull: none`), `depth_write: false`, in the transparent queue (`3000`). Built on the `pbr` shader. ## Inputs - `colors.base_color` (`1.0, 1.0, 1.0`) — the glyph colour. - `render.depth_write` (`false`) — glyphs blend without occluding each other. - `render.cull` (`none`) — text is visible from both sides. - `floats.roughness` (`0.5`) / `floats.metallic` (`0.0`) — dielectric defaults.

# Grid Background A procedural background/reference-grid surface built on `@builtin::shaders.grid_bg`. It draws grid lines over a black base colour (`0.0, 0.0, 0.0`) with full roughness (`1.0`) and no metallic response, rendered opaque with culling disabled (`cull: none`) and instancing enabled so it can back many objects at once. ## Inputs - `colors.base_color` (`0.0, 0.0, 0.0, 1.0`) — black backdrop behind the grid lines. - `floats.roughness` (`1.0`) — fully diffuse, no highlights. - `render.cull` (`none`) — visible from both faces. - `render.instancing` (`true`) — supports instanced draws.

# Standard Default The baseline PBR surface — a neutral white base colour (`1.0, 1.0, 1.0`), half roughness (`0.5`), non-metallic (`0.0`), wired with the full standard texture set (base colour, normal, roughness-metallic, emissive, occlusion) and the `_NORMALMAP` / `_OCCLUSIONMAP` keywords enabled. Opaque, back-face culled, instanced, in the opaque queue (`2000`). Built on `@builtin::shaders.pbr`. This is the starting point most materials copy and retint. ## Inputs - `colors.base_color` (`1.0, 1.0, 1.0`) — the albedo tint over the base colour texture. - `floats.roughness` (`0.5`) / `floats.metallic` (`0.0`) — dielectric, mid-gloss default. - `floats.normal_strength` (`1.0`) / `floats.ao_strength` (`1.0`) — normal-map and occlusion intensity. - `textures.normal_texture` / `textures.roughness_metallic_texture` / `textures.occlusion_texture` — the PBR map slots, seeded with neutral defaults.

# postReference_grey18 A lit 18% grey (middle grey) surface, rough and dielectric: what a light of known intensity is read off in the post-verification reference scenes.

# Parallax Cube (Flat) A brick surface built on `@builtin::shaders.pbr_parallax_occlusion` with `parallax_depth_scale = 0`, so the ray-march is bypassed and the shared brick textures render as plain textured PBR (rough `0.7`, non-metallic, white base colour). Opaque, back-face culled, queue `2000`. Pair it with `parallax_cube` to A/B the parallax effect from a fixed viewpoint. ## Inputs - `floats.parallax_depth_scale` (`0.0`) — disables the occlusion ray-march, flattening the surface. - `floats.roughness` (`0.7`) — matte brick finish. - `floats.normal_scale` (`1.0`) — strength of the normal map. - `textures.height_texture` — the brick height map (unused while depth scale is `0`).

# postReference_siemensStar A Siemens star of 36 spokes, 0.9 on 0.02: the spokes narrow below a pixel toward the centre, where a temporal resolve aliases. Drawn unlit by `@builtin::shaders.referenceChart`, so a picture of it is measured against the light its properties state. Part of the post-verification reference scenes (`@builtin::scenes.postReference.*`); `@builtin::modules.postMetrics` reads them.

# Skybox An unlit cubemap skybox rendered from the inside of the mesh, built on `@builtin::shaders.cubemap_unlit`. Uses front-face culling and no depth write so it draws behind all scene geometry (queue `1000`), sampling the built-in `Ryfjallet_cubemap` environment. ## Inputs - `textures.base_color_texture` — the cubemap sampled as the background (`Ryfjallet_cubemap`). - `floats.reflect_mode` (`0.0`) — samples the cube directly as a background rather than as a reflection. - `colors.base_color` (`1.0, 1.0, 1.0`) — tint applied to the sampled cubemap.

# postReference_greyWedge The grey wedge: one column per whole stop from -10 to +10, each middle grey (0.18) at that exposure. Drawn unlit by `@builtin::shaders.referenceChart`, so a picture of it is measured against the light its properties state. Part of the post-verification reference scenes (`@builtin::scenes.postReference.*`); `@builtin::modules.postMetrics` reads them.

# Checkerboard White A static white/grey checkerboard rendered by `@builtin::shaders.checkerboard`, alternating a white base colour (`1.0, 1.0, 1.0`) with a dark grey check colour (`0.3, 0.3, 0.3`). Animation is disabled (`animation_speed 0.0`), giving a fixed, neutral grid — ideal as a level-design blockout or scale-reference floor. Opaque, non-metallic (`metallic 0.0`) at mid roughness (`0.5`). ## Inputs - `colors.base_color` — the white square colour. - `colors.check_color` — the dark grey square colour. - `floats.animation_speed` (`0.0`) — held at zero for a static pattern. - `floats.roughness` (`0.5`) — diffuse spread on the squares.

# postReference_white A flat unlit white of 0.8 light: the thin geometry of the temporal reference scene (wires, a fence, a fan's blades) drawn against the dark, so every pixel it touches stands out from its neighbours. Drawn by `@builtin::shaders.referenceChart`. Part of the post-verification reference scenes (`@builtin::scenes.postReference.*`); `@builtin::modules.postMetrics` reads them.

# parallax_cube Brick wall material using `@builtin::shaders.pbr_parallax_occlusion` with the parallax march enabled (`parallax_depth_scale = 0.08`, 48 ray-march layers). Pair with `parallax_cube_flat` for a same-textures, no-POM A/B comparison. ## Shader `@builtin::shaders.pbr_parallax_occlusion` — see that shader's README for the full parameter list. ## Textures All from `@builtin::textures.parallax_bricks` (height/normal derived from three.js's MIT-licensed `brick_bump` + `brick_diffuse`): - `base_color_texture` → `bricks_albedo` - `normal_texture` → `bricks_normal` - `roughness_metallic_texture` → `bricks_roughness` - `occlusion_texture` → `bricks_ao` - `height_texture` → `bricks_height` ## Usage ```luau Material.Apply(entityId, "parallax_cube") -- Override at runtime: Material.SetProperty("parallax_cube", "parallax_depth_scale", 0.12) ``` Pair it with `parallax_cube_flat` (same textures, `parallax_depth_scale = 0`) to compare the ray-marched surface against a flat-mapped baseline. ## Notes - `Material.SetProperty` mutations are global — every entity using `parallax_cube` sees the change. If you need per-entity variation, derive a new material name and override the property there. - Use under any standard camera (forward path). The deferred path is not yet POM-aware; materials applied to a deferred camera will render as plain textured PBR.

# Neon A glowing cyan neon surface built on `@builtin::shaders.pbr` with emission enabled. It pairs a bright cyan-blue base colour (`0.2, 0.8, 1.0`) with a matching emissive colour driven hard by `emissive: 5.0`, so it reads as a self-lit light source. Low roughness (`0.2`), non-metallic, opaque, instanced, with the `_EMISSION` keyword enabled. ## Inputs - `colors.emissive` (`0.2, 0.8, 1.0, 1.0`) — cyan glow colour. - `floats.emissive_intensity` (`5.0`) — strong emissive intensity (feeds bloom). - `colors.base_color` (`0.2, 0.8, 1.0, 1.0`) — matching cyan base tint. - `floats.roughness` (`0.2`) — glossy surface under direct light.

# 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.

# postReference_checker A checker of 64 cells across, 0.8 on 0.03: the high-frequency background a fast object crosses. Drawn unlit by `@builtin::shaders.referenceChart`, so a picture of it is measured against the light its properties state. Part of the post-verification reference scenes (`@builtin::scenes.postReference.*`); `@builtin::modules.postMetrics` reads them.

# postReference_colorChecker The 24 patches of the ColorChecker Classic, each its published sRGB value read as linear reflectance. Drawn unlit by `@builtin::shaders.referenceChart`, so a picture of it is measured against the light its properties state. Part of the post-verification reference scenes (`@builtin::scenes.postReference.*`); `@builtin::modules.postMetrics` reads them.

# Error Test Intentionally broken material used to exercise the renderer's error-handling and fallback paths. It targets `@builtin::shaders.error_shader` and carries a bright magenta base colour (`1.0, 0.0, 1.0`) — the classic "missing/failed" flag colour — with mid roughness (`0.5`), opaque render type, and back-face culling. ## Inputs - `colors.base_color` (`1.0, 0.0, 1.0, 1.0`) — magenta error flag tint. - `floats.roughness` (`0.5`) — neutral surface roughness. - `render.type` (`opaque`) / `render.queue` (`2000`) — drawn in the standard opaque pass.

# Animated Color An opaque, back-culled surface whose colour animates over time, driven by `@builtin::shaders.animate_shader`. Starts from a white base colour (`1.0, 1.0, 1.0`) with an `emissive` of `1.0` so the shifting colour reads brightly, at mid roughness (`0.5`) and fully non-metallic (`metallic 0.0`). ## Inputs - `colors.base_color` — the starting colour the animation modulates. - `floats.emissive` (`1.0`) — self-illumination strength of the animated colour. - `floats.roughness` (`0.5`) — matte diffuse spread. - `floats.metallic` (`0.0`) — dielectric, non-metallic surface.

# Error Text A 3D "ERROR" text model used as the visible fallback when an asset fails to load — spawned in place of missing geometry so a broken reference is obvious in-scene instead of silently invisible. Decomposed from `ERRORText.fbx` into this bundle (mesh + material + texture + entity template). ## Composition - Root `error_text` → `Sketchfab_model` → the `ERRORText.fbx` node hierarchy. - Carries the extruded "ERROR" letter mesh, its material, and texture as private subassets. ## Usage Spawned automatically by the engine as the placeholder for an unresolved asset; can also be spawned directly to test the fallback path.

# Plastic White A clean white plastic — a non-metallic PBR surface with a pure white base colour (`1.0, 1.0, 1.0`) and mid roughness (`0.5`) for a soft dielectric sheen. Built on `@builtin::shaders.pbr`. Opaque, back-face culled, queue `2000`. ## Inputs - `colors.base_color` (`1.0, 1.0, 1.0`) — the white plastic tint. - `floats.roughness` (`0.5`) — soft, semi-glossy highlight. - `floats.metallic` (`0.0`) — dielectric (non-metal) response. - `floats.emissive` (`0.0`) — no self-illumination.

# postReference_darkRamp A ramp of light from 0 at the left edge to 0.1 at the right: the dark gradient an undithered 8-bit display path bands on. Drawn unlit by `@builtin::shaders.referenceChart`, so a picture of it is measured against the light its properties state. Part of the post-verification reference scenes (`@builtin::scenes.postReference.*`); `@builtin::modules.postMetrics` reads them.

# Lit Checkerboard A static, lit checkerboard surface built on `@builtin::shaders.lit_checkerboard` — the default ground material for newly seeded worlds. It uses a neutral light-grey base colour (`0.85, 0.85, 0.85`) with a grey emissive tint (`0.35, 0.35, 0.35`) so the pattern stays readable in dim scenes, high roughness (`0.7`), no metallic, opaque, and instanced. ## Inputs - `colors.base_color` (`0.85, 0.85, 0.85, 1.0`) — neutral grey checker palette. - `colors.dark_color` (`0.35, 0.35, 0.35, 1.0`) — the dark square colour, close enough to the base that the pattern stays readable in low light. - `floats.roughness` (`0.7`) — mostly diffuse surface. - `render.instancing` (`true`) — supports instanced draws.

# Decal Default The default material a `DecalProjector` stamps when none is assigned. A flat cyan tint (`0.05, 0.95, 1.0`) on `@builtin::shaders.pbr`. Assign a material with a `base_color_texture` to project a texture; the projector samples the material's base colour at the box-local XY of every surface inside its projection box.

# Sky Equirectangular An equirectangular panorama sky/environment background built on `@builtin::shaders.equirect_sky`. Renders with no culling and no depth write behind all geometry (queue `1000`), with adjustable rotation and exposure. Assign an equirectangular image to `sky_texture` (via `material.setTexture` or a Skybox) to display a panorama. ## Inputs - `textures.sky_texture` — the equirectangular panorama image to sample. Falls back to black, so a sky with nothing assigned reads as night rather than as an error. Assign a `.texture` by guid, identity, name, or path: ```luau renderer.material.setTexture("@builtin::materials.sky_equirect", "sky_texture", "my_panorama.texture") ``` An image dropped into `/zero/source` imports into a sibling `<stem>.texture` container and the loose file is removed, so reference the container (or its identity) rather than the original image path. - `floats.rotation` (`0.0`) — yaw rotation of the panorama around the vertical axis. - `floats.exposure` (`1.0`) — brightness multiplier applied to the sampled colour.

# error_marker The material of the ERROR sign a Model or SkinnedModel shows in place of a mesh that failed to resolve, to become GPU-resident, or to pose. It draws the `error_marker` shader's magenta checker.

# assetType.shared.ref Builds the metatable every `AssetRef` (the `{ __ref, type, name, guid, identity, path }` envelope returned by `asset.resolve` / `asset.ref`) carries. Replaces the per-call C metatable that used to live in `crates/zero_scripting/src/ffi/bindings/asset.rs::attach_asset_ref_metatable`. ## Public API ```lua local assetRef = require("@builtin::assetTypes.assetType.shared.ref") -- Called by the Rust factory (push_asset_ref_handle) via -- _G.__build_asset_ref_proxy after the envelope fields are set. assetRef.build(envelope) -- attaches AssetRefMT, returns the table ``` The module exposes no invalidation surface — discovery is registry-driven and hot-reload is transparent (see "Discovery and hot-reload" below). ## Method dispatch order `ref.foo` is resolved in this order: 1. **Default methods** — `getSource` / `getBytes` / `getText` / `exists` / `inspect` and the lazy `meta` property. Per-type definitions cannot override these (engine contract from gh#1889). 2. **Per-type `ref` table** — discovered through `asset.resolve(<typename>, "assetType")` + `require(<identity>.behavior)`. The lookup resolves to whichever `<typename>.assetType/` folder is currently registered for the typename (built-in, user, or library-vendored) and pulls its `ref` methods. 3. **Nil** — unknown key, same shape as the original C metatable. ## Adding methods for a new asset type Drop a `behavior.luau` into the type folder: ``` src/lua/lib/assetTypes/<typename>.assetType/ ├── type.yaml -- structural spec (existing) ├── behavior.luau -- ref + global behaviour (new) └── template/ -- placeholder body (existing) ``` `behavior.luau` returns: ```lua return { ref = { --!desc Per-instance method on every `<typename>` AssetRef. myMethod = function(self, ...) ... end, }, global = { -- Reserved for the asset.<typename>.* surface — not consumed -- yet; included so the contract from gh#1889 lands cleanly. }, } ``` Within `ref` methods, `self` is the AssetRef envelope: `self.path`, `self.identity`, `self.guid`, `self.type`, `self.name` are available. Engine-required fields (`guid`, `path`, `identity`, `type`) must not be redefined. ## Discovery and hot-reload Type discovery uses the asset registry, so it doesn't matter where a `<typename>.assetType/` folder lives — engine built-ins under `@builtin::assetTypes.<X>`, user types dropped under `/zero/source/<X>.assetType/`, or types vendored inside an imported library all resolve identically. The dispatcher walks `asset.resolve(<typename>, "assetType")` → canonical identity → `require <identity>.behavior` on every miss; the asset registry is the cache for the resolve half and Luau's `_LOADED` is the cache for the require half. Hot-reload is transparent. When a `<typename>.assetType/behavior.luau` is rewritten through VFS, the engine's `invalidate_require_cache_for_state` re-runs the module and mutates the cached `_LOADED[<identity>.behavior]` table in place. Dispatch reads `mod.ref` on every access (rather than caching a sub-pointer), so existing AssetRefs see the new methods on the very next access — no Rust-side hook into this module is needed, and no invalidation API is exposed for callers to call. The same registry-driven path also handles type **registration** correctness: dropping a new `<typename>.assetType/behavior.luau` updates the asset registry, the next `asset.resolve(<typename>, "assetType")` returns the new ref, and AssetRefs of that type immediately gain the new methods. ## Why Luau, not Rust The asset surface needed per-category behaviour (`material:getProperties()`, `bundle:instantiate(entityId)`, `tool:run(args)`) and the old shape couldn't grow without an FFI change per method. Owning the proxy in Luau means: - Type-specific methods ship as content (the `<typename>.assetType/` folder), not engine code. - Adding a new asset type drops in a new folder; no Rust rebuild. - Methods can call any other Luau global (`vfs`, `asset`, `Material`, `entity`, etc.) directly, instead of going through narrow FFI primitives. ## Consumers - `crates/zero_scripting/src/ffi/bindings/asset.rs::attach_asset_ref_metatable` — the Rust factory that pushes envelopes invokes `_G.__build_asset_ref_proxy` once per push. - Every Luau call site of `asset.resolve` / `asset.ref` / `entity(id).component.X.material` / any binding declared `AssetRef<...>` — they all receive envelopes built through this module.

# proc.types The procgen type system: core type tags + socket assignability for graph validation. Part of `@builtin::systems.procgen.proc`.

# Brushed Metal A brushed metallic surface built on the `pbr` shader — fully metallic (`metallic: 1.0`) with a neutral grey base colour (`0.6, 0.6, 0.6`) and moderate roughness (`0.3`) that softens reflections into the muted sheen of brushed steel or aluminium. Opaque, back-face culled, instanced, with the `_METALLICSPECGLOSSMAP` keyword enabled. ## Inputs - `colors.base_color` (`0.6, 0.6, 0.6, 1.0`) — neutral metal grey. - `floats.metallic` (`1.0`) — fully metallic. - `floats.roughness` (`0.3`) — softened, brushed reflections. - `textures.base_color_texture` (`default:white`): the white base texture the colour multiplies against, so the surface renders `base_color` alone.

# postReference_emitter A flat emitter answering with 16 times the display's white: the source a bloom reading is taken around. Drawn unlit by `@builtin::shaders.referenceChart`, so a picture of it is measured against the light its properties state. Part of the post-verification reference scenes (`@builtin::scenes.postReference.*`); `@builtin::modules.postMetrics` reads them.

# Sky Solid A flat solid-colour background built on `@builtin::shaders.solid_sky`. Renders with no culling and no depth write behind all geometry (queue `1000`), filling the sky with a single dark-grey colour (`0.2, 0.2, 0.2`) at unit exposure. ## Inputs - `colors.solid_color` (`0.2, 0.2, 0.2`) — the flat fill colour of the background. - `floats.exposure` (`1.0`) — brightness multiplier applied to the fill colour.

# Grass A soft green ground surface built on `@builtin::shaders.grass_material`, with a natural green base colour (`0.22, 0.62, 0.16`), high roughness (`0.75`) for a diffuse, non-shiny look, and no metallic or emissive contribution. It inherits the Rust-side render defaults (opaque, back-face culled, queue `2000`) so its pipeline matches the library variant compiled at startup. It leaves the shader's `sway` at its default of `0`, so it shades whatever geometry it is applied to and leaves every vertex where the mesh puts it; `@builtin::materials.grass_blades` is the same green on a blade mesh that bends. ## Inputs - `colors.base_color` (`0.22, 0.62, 0.16, 1.0`) — the grass green tint. - `floats.roughness` (`0.75`) — matte, diffuse surface. - `floats.metallic` (`0.0`) / `floats.emissive` (`0.0`) — non-metallic, non-glowing.

# Cubemap Env A chrome-ball environment surface that samples a cubemap for mirror-like reflections, built on `@builtin::shaders.cubemap_unlit`. `reflect_mode` (`1.0`) selects the reflection path, and the `Ryfjallet_cubemap` builtin texture supplies the environment. Opaque, with a white base colour (`1.0, 1.0, 1.0`) so the cubemap colours pass through untinted. ## Inputs - `textures.base_color_texture` (`@builtin/textures/Ryfjallet_cubemap`) — the environment cubemap that is reflected. - `floats.reflect_mode` (`1.0`) — selects the reflection sampling mode. - `colors.base_color` — white tint that leaves the reflected colours unchanged.

# Solid Line A flat, opaque line surface with a bright green base colour (`0.0, 1.0, 0.5`) for drawing gizmos, paths, and debug geometry. Opaque, back-face culled, instanced, and rendered in the opaque queue (`2000`). Built on `@builtin::shaders.line_material`. ## Inputs - `colors.base_color` (`0.0, 1.0, 0.5`) — the line colour. - `floats.roughness` (`0.5`) — surface roughness. - `floats.emissive` (`0.0`) — no self-illumination. - `render.instancing` (`true`) — many lines draw in a single instanced batch.

# Glass Clear glass — a smooth, transparent PBR surface with a faint blue tint (`0.9, 0.95, 1.0`) and low alpha (`0.3`). Rendered in the transparent queue with backface culling off (`cull: none`) so both faces of thin geometry show. Built on `@builtin::shaders.pbr`. ## Inputs - `colors.base_color` — tint and opacity (the alpha channel drives how much shows through). - `floats.roughness` (`0.0`) — perfectly smooth; raise for frosted glass.

# Default The neutral fallback surface — a plain white, non-metallic PBR material with mid roughness (`0.5`), sampling the built-in white texture. This is what an object renders as when no material is assigned. Built on `@builtin::shaders.pbr`. ## Inputs - `colors.base_color` — the flat tint (white by default). - `floats.roughness` (`0.5`) / `floats.metallic` (`0.0`) — a neutral matte dielectric. - `textures.base_color_texture` — the built-in `default:white` texture.

# Triplanar Checker A checkerboard surface projected triplanarly, so the pattern stays uniform across arbitrary geometry with no UVs and no stretching. Neutral white base colour (`1.0, 1.0, 1.0`), half roughness (`0.5`), non-metallic, with a projection sharpness of `4.0` controlling how tightly the three axis projections blend at edges. Opaque, back-face culled, instanced, in the opaque queue (`2000`). Built on `@builtin::shaders.triplanar`, sampling `@builtin/textures/array_texture`. ## Inputs - `floats.triplanar_sharpness` (`4.0`) — blend tightness between the X/Y/Z projections. - `colors.base_color` (`1.0, 1.0, 1.0`) — tint over the projected texture. - `textures.base_color_texture` — the projected checker source (`@builtin/textures/array_texture`). - `floats.roughness` (`0.5`) / `floats.metallic` (`0.0`) — dielectric, mid-gloss default.

# deprecatedParticles (deprecated) > **Deprecated.** This belongs to the earlier particle substrate. It stays loadable by identity and guid for content that already uses it; nothing new should use it, and search does not offer it. Particles are procgen sim nodes (`sim.spawn`, `sim.particles`, `sim.shader`) played through an effect: use `@builtin::assetTypes.effect`. The package holds the GPU particle engine module (`engine`), the `deprecatedParticles` module over it, the `DeprecatedParticleEmitter` and `DeprecatedSimpleParticleEmitter` components, the shaders, compute shaders and materials they draw with, and a demo scene. The package's `.metadata` carries the deprecation marker, so every asset inside is deprecated.

# Plastic Red A glossy red plastic — a non-metallic PBR surface with a saturated red base colour (`0.8, 0.1, 0.1`) and mid roughness (`0.5`) for a soft dielectric sheen. Built on `@builtin::shaders.pbr`. Opaque, back-face culled, queue `2000`. ## Inputs - `colors.base_color` (`0.8, 0.1, 0.1`) — the red plastic tint. - `floats.roughness` (`0.5`) — soft, semi-glossy highlight. - `floats.metallic` (`0.0`) — dielectric (non-metal) response. - `floats.emissive` (`0.0`) — no self-illumination.

# Cel Shaded A stylised, toon-shaded opaque surface built on `@builtin::shaders.extended_material`, with a warm red-orange base colour (`0.9, 0.3, 0.2`). The sun's light is cut into flat bands that multiply the base colour, so every band renders the hue of `base_color` and only its brightness steps; ambient light lifts the side facing away from the sun in the same hue. High roughness (`0.8`) keeps the surface matte: its specular term stays below the first band, so each lit band is one flat colour. ## Inputs - `colors.base_color`: the surface colour every band renders in, multiplied by `base_color_texture`. - `floats.roughness` (`0.8`): the size and strength of the specular highlight, which is banded with the rest of the sun's light; 0 is a small bright highlight. At four bands, a roughness of 0.5 or more keeps the highlight below the first band, so none shows. - `floats.quantize_steps` (`4`): the number of bands the sun's light is cut into; 0 shades smoothly. - `textures.base_color_texture`: an optional surface texture, drawn multiplied by `base_color`. Unset, it is white, and the surface renders `base_color` alone.

# 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.

# Material (asset type) A material is a named, configured instance of a `.shader`. The shader defines the surface look (lighting model, available property fields, texture slots); the material picks values for those fields and a shader to bind to. Renderable entities reference materials, not shaders, so the same geometry can wear different materials and the same material can be reused across many entities. Entities sharing one material can still differ in a value: every drawn object carries four `vec4` lanes of its own that a surface shader reads as `input.shader_data[lane]` and `renderer.instanceData.set` writes. Use that for a dissolve at its own progress per subject, a hit flash at its own age, a fill level per instance — a material per entity is for when the LOOK differs, not when a number does. > New to how a material relates to its shader, its textures, and the live GPU > material behind it? Read `core/resource-model` first. It also covers the > difference between an authored `.material` asset (this type) and a runtime GPU > material made with `renderer.material.create`. ## When to use one - You want a named surface configuration an entity wears by referencing it from its `Model` component (`material = "@.../<Name>"`). - You want runtime property tweaks (`asset.resolve(ref):setProperty(...)`) to affect every entity using the material at once. - You want to publish a curated look (`Gold`, `RedGlow`, `BrickWall`) other authors can reuse without re-typing shader bindings. If you need a brand-new lighting model or a custom visual effect, you need a `.shader` first; the material wraps it. ## Where it lives - Source: `/zero/source/.../<Name>.material/` - Identity: `<Name>` (the `.material` suffix strips). - Folder shape: - `mat.yaml` — canonical material spec (shader + property values). **Required.** - `preview.png` — the material's rendered shader-ball still, its persisted visual description. **Required.** Rendered when the material is staged (`zm add`) with its preview missing or stale, and by `generatePreviews`; it syncs, publishes, feeds image-based search, and gives browsers a thumbnail. - `README.md` / `.metadata` — optional prose + tags, indexed when an author writes real ones. - `textures/` — optional folder for embedded textures. Validator allows the folder; its interior is unrestricted. - `shaders/` — optional folder for a co-located custom shader. Same rule. ## How to create one ```luau asset.create("material", "<Name>") -- Creates: /zero/source/<Name>.material/ -- mat.yaml (shader binding + property scaffold) -- preview.png (rendered when the material is staged with `zm add`; the -- picture lands as a change the next `zm add` stages) -- `folder` places it in a subfolder of /source instead of the root: asset.create("material", "<Name>", { folder = "materials" }) ``` Pass the shader and initial values through `asset.create`, then tune with `setProperty` and keep what you tuned with `saveDefinition`: ```luau local mat = asset.create("material", "<Name>", { shader = "@builtin::shaders.pbr" }) mat:setProperty("base_color", { 0.8, 0.6, 0.1, 1 }) mat:setProperty("roughness", 0.3) mat:saveDefinition() -- writes the tuned values into mat.yaml ``` This mints the `.material` asset and returns a handle you tune with `setProperty`. A set is a runtime change: it reaches the GPU material and every entity wearing it, and `saveDefinition` is the call that writes it into `mat.yaml`, so a property driven every frame costs no file write and leaves the authored file as its author wrote it. A purely runtime `asset.create` lives only for the session. For an ephemeral, runtime-only GPU material that is not an asset at all, use `renderer.material.create` instead (see `core/resource-model`). ## How it operates 1. **Property reflection.** The bound shader's uniform struct fields become the material's configurable properties — no manual property declarations needed. `naga` introspects the shader at load. 2. **Property values.** `mat.yaml` groups values by type, each block keyed by the shader's field names: `properties:` holds scalars and colors/vectors, `ints:` holds integer-typed fields, `bools:` holds boolean-typed fields, and `textures:` holds texture slots. Omitted fields take the shader's default. A scalar is a bare number (`roughness: 0.5`); a color or vector is an array (`base_color: [1, 1, 1, 1]`). `shader:` is the shader's identity string. This is the shape every material the engine writes uses. A `saveDefinition` writes the changed values into the file where they already stand and leaves the rest of it — its comments, the order of its keys and blocks, the spelling of its literals — untouched. The older `floats:` / `colors:` blocks (with `{ r, g, b, a }` map colors) still load for materials hand-authored that way. 3. **Render state.** `render:` holds how the mesh is drawn rather than what the shader reads: `blend` (the equation the fragment composites with, also spelled `type`), `cull`, `depth_write`, `depth_compare` and `topology`. The `.shader` type README's "The render block" section lists every value each key takes, and `asset.create`'s `render` argument takes the same keys and values. 4. **Application.** An entity wears a material by referencing it from its `Model` component (`material = "@.../<Name>"`). Materials affect every entity that references them; runtime `asset.resolve(ref):setProperty(...)` changes propagate to all of them immediately, and last until the next mode change unless `saveDefinition` writes them into `mat.yaml`. 5. **Texture binding.** Texture slots accept `color:r,g,b,a` for solid colors, `default:white` / `default:black` / `default:normal` for the engine's own fallback texels, `@builtin::textures.<name>` for builtins, `path/to/image.png` for file textures, or a render-target handle for camera renders. The GPU texture cache reads the `color:` and `default:` forms from the string itself, so a slot written in one names no asset and carries nothing with the material when it travels; every other form names a texture asset the slot depends on. A texture in `base_color_texture` is multiplied by `base_color`: every built-in surface shader declaring both draws the texture's colour times `base_color`, channel by channel. Under the default white `base_color` the texture shows as itself, and a coloured `base_color` tints it. The two read a colour differently: `base_color` is linear, and the slot reads its texels as sRGB-encoded, a `color:` value's included, the way it reads an image. A colour stated in both places is therefore multiplied by a darker copy of itself: `color:0.62,0.14,0.05,1` in the slot decodes to `0.34, 0.017, 0.0039`, so beside `base_color` `0.62, 0.14, 0.05` the surface draws `0.21, 0.0024, 0.0002`, far darker than either. State a solid colour once, as `base_color`, and leave the slot at its default white. 6. **Hot reload.** Editing `mat.yaml` repacks the GPU uniform buffer on the next frame; visible immediately. 7. **Inspector.** `type.yaml` names `inspector: { type: "inspector.luau" }`, and `inspector.luau` declares the material's sections beside the generic ones: `shader` (the bound shader, swappable), `properties` (each shader field as its typed control) and `textures` (each texture slot as an asset chip). They read the material through `mat:getShaderRef()` (the bound shader's ref, `~` expanded) and `mat:getTextures()` (slot name → `{ ref, name }`: the bound texture's guid and the id the material names it by). An edit there is an authoring write: `mat:writeProperty(name, value)` and `mat:writeTexture(slot, texture)` write the value into `mat.yaml` (and drop the session's own value for it, so the material reads what the file holds), and `setShader` rewrites the file; inside an undo operation each file write is recorded, so undo puts `mat.yaml` back. `setProperty` / `setTexture` stay runtime writes that last until the next mode change. ## Discovery - `asset.list("material")` — every registered material. - `asset.inspect("<name>")` — shader binding, property values, source path, this type README. - `ls /zero/source/<Name>.material` lists the files the folder holds. - `asset.resolve("<name>"):getProperties()` — the property fields exposed by the bound shader, each at the value it currently holds: what `mat.yaml` authored until something writes to the material, and the written value from then on, whichever call wrote it. That is the value the surface is drawn with. Read them back rather than guessing names; which fields exist comes from the shader. - `asset.resolve("<name>"):getDefinition()` — the authored `mat.yaml` bytes, the value the material rests at. - `asset.resolve("<name>"):getShader()` — the shader the material binds. ## Authoring conventions - Use lowercase, descriptive names (`brushed_steel`, `red_glow`, `tarmac_wet`). Avoid shader-name suffixes in the material name — the binding lives in `mat.yaml::shader`. - Drive every property the shader exposes; defaults are a fallback, not a contract for which fields exist. - Embed textures alongside the material (`textures/` subfolder) when they're used only by this material; reference shared textures from `@builtin::textures.*` or a library. ## Common pitfalls - **Property names must match the shader's uniform struct exactly** (case-sensitive). Misnamed properties silently get the shader's default. - **`base_color_texture` multiplies `base_color`.** A `color:` texture holding the same value as `base_color` multiplies the colour by its own sRGB-decoded value, so the surface renders far darker than the value written. Write a solid colour as `base_color` alone. - **Broken shaders break the material.** A material whose shader has a parse error renders as the magenta checkerboard. Inspect the shader first if the material looks wrong. - **`setProperty` targets the material, not the entity.** Changes affect every entity that references the material. - **`setProperty` is a runtime change.** It reaches the GPU, not the file: call `saveDefinition` to write the current values into `mat.yaml`. For a per-entity override that no other entity sees, give the entity its own copy with `Model:applySessionMaterial(renderer.material.create(...))`. - **Renaming the folder changes the identity.** Update every `Model` component and `asset.create` callsite that references it. ## Related types - `.shader` — defines what properties exist; required before a material can bind to it. - `.preset` — captures a component configuration; conceptually similar to a material, but for components instead of shaders.

# ScreenSpaceReflections Reflections off the scene's own drawn frame, as a one-feature component. A scene lists its features together, each with its settings, on `RenderFeatures` (`{ feature = "@builtin::systems.reflections.ssr", settings = { ... } }`); this component carries the same knobs as fields for one feature. ```lua local id = entity.spawn("reflections").id entity(id).component.add("ScreenSpaceReflections", { intensity = 1.0, maxDistance = 40, quality = "high", }) ``` Polished floors start reflecting what stands on them, wet ground reflects what is above it, and metal picks up its surroundings — all from geometry the camera can already see, with nothing authored per surface. Roughness decides who gets them. A screen-space ray traces one direction, which is a mirror; `roughnessCutoff` is where that stops being a fair stand-in for a surface's real lobe, and past it the pass leaves the surface alone. Every field is live: edit one in the inspector and the reflections follow. Setting `intensity` to 0 turns them off without losing the rest of the settings. How much a reflection shows through is the surface's own Fresnel term, so metal takes almost all of it and a dielectric floor takes a few percent head-on and more at a grazing angle — the same way a wet road reads dry underfoot and mirror-like down the street. For code that adjusts reflections at runtime, reach for `@builtin::systems.reflections.ssr` — same options, no component. The full description of what each knob does and how the passes work is in the package readme: `guides { path = "systems/reflections" }`.

# Polished floor A polished stone floor with three coloured pillars standing on it, under an afternoon sky, with screen-space reflections listed on the scene's `RenderFeatures` entity — so the floor reflects the pillars, and a player walking across it, rather than the sky alone. Load it with `scene.load("@builtin::systems.reflections.demo.polished_floor")`. Players arrive facing the pillars from floor height, which is the grazing angle a polished dielectric reflects at most strongly. ## What it shows - **The feature on one entity.** `render_features` carries a `RenderFeatures` list with `@builtin::systems.reflections.ssr` at `intensity = 1`, `maxDistance = 60`, `quality = "high"`. Delete the entity and the floor mirrors the sky alone; put it back and the pillars stand in the floor. - **Only what the camera sees.** A pillar's reflection comes from the frame the camera drew, so turning away from a pillar takes its reflection with it, and the reflection fades toward the screen edge rather than cutting off. - **The environment underneath.** Where a ray finds nothing the floor keeps the sky reflection the environment gives it, at the same mip and Fresnel weight, so the seam between the two is a change of content and not of brightness. - **Roughness decides who reflects.** The floor sits at roughness 0.06, the pillars at 0.55 — above the feature's `roughnessCutoff` — so the floor is the one surface tracing reflections in the scene. ## Contents - `floor` — a 60 m slab of `PolishedStone`, a near-black dielectric at roughness 0.06, with a collider. - `pillar_1..3` — 1.6 × 5 × 1.6 m boxes in `PillarRed`, `PillarGreen`, `PillarBlue`, sunk into the slab. - `sun`, `ambient`, `sky` — a side-lit afternoon under a `ProceduralSky`. - `render_features` — the `RenderFeatures` entity this scene exists for. - `PlayerSetups` / `Spawns` — the humanoid player on an orbital-follow camera, spawning in front of the pillars. The scene's player intent is `"spawns"`. ## Entry point - `entrypoint.luau` — nothing to set up: the reflections run from the `RenderFeatures` entity the moment the scene loads.

# ssr Screen-space reflections — polished floors reflect what stands on them, from the frame the engine has already drawn. ```lua local ssr = require("@builtin::systems.reflections.ssr") ssr.set({ intensity = 1, maxDistance = 40, quality = "high" }) ssr.get() --> the settings in force ssr.active() --> are the reflection passes running ssr.clear() --> off, settings kept for the next set() ``` `set` takes any subset — omitted fields keep their current value, so adjusting one knob does not mean restating the rest. An `intensity` of 0 turns reflections off and releases the passes rather than running them at zero strength. `roughnessCutoff` is the field that decides who gets reflections at all. A screen-space ray traces one direction, which describes a mirror; past the cutoff a real surface scatters over a lobe too wide for one ray to stand in for, and the pass leaves those surfaces alone. `maxDistance` and `quality` trade against each other. Quality sets how many steps the march spends, so a long distance at a low quality samples coarsely — reflections thin out at range rather than disappearing, because refinement adapts to the step size on its own. For reflections a scene should simply have, author the `ScreenSpaceReflections` component instead — it carries the same settings, persists with the scene, and edits live in the inspector. This module is for code that changes reflections at runtime: a quality slider, a cutscene, weather turning pavement wet. The full description of what each knob does and how the passes work is in the package readme: `guides { path = "systems/reflections" }`.

# ssr The render feature behind `ScreenSpaceReflections` and `@builtin::systems.reflections.ssr`. One compute pass runs at the `afterDepthPrepass` seam, once the visibility raster has laid the frame's depth and before anything shades: | order | pass | output | |---|---|---| | 60 | `ssr_trace` | reflected colour plus a confidence weight, per pixel, into `@scene.reflection` | That channel is what a material's environment term reads the same frame, at its own pixel: the traced reflection stands in for the probes and the sky to the degree the trace trusts it, and the material's own Fresnel, roughness and tint weigh it into the pixel the way they weigh any environment. Nothing here touches the lit picture. The trace marches against this frame's depth, which the visibility raster has just written, so the reflection stands where the camera is now. What it reads about the surfaces — the reflecting surface's normal and roughness, the hit's normal and its colour — comes from the previous frame: the G-buffer as that frame left it (`readsPrevious`), and `@scene.colorHistory`, the light it ended with, each reprojected through the previous view-projection `@frame.camera` carries in its rows `[5..9)`. A point the previous frame did not show reflects its environment alone. ## The march `ssr_trace` reflects the view ray about the surface normal and walks it through the depth buffer. Steps are uniform in **screen** space, not world space. A ray heading toward the horizon covers enormous world distance across a few pixels, so stepping in world units there means either missing every thin occluder near the camera or spending the whole budget on distance nothing can be seen at. The world parameter is recovered from the screen parameter through `1/w`, which is what interpolates linearly under perspective. At each step the ray's world position is compared against the world position reconstructed from the depth sample under it. Comparing in world space is what lets `thickness` mean a distance in world units rather than a depth-buffer epsilon whose meaning changes with range. The march looks only for the **crossing** — where the ray first passes behind the depth buffer. Thickness is tested after bisecting that crossing, not during the march: one march step covers roughly as much depth as a surface is thick, so a ray tested during the march can jump from in front of a surface to well behind it without ever landing inside it. Bisection runs for whichever is larger, the quality tier's budget or however many halvings bring one march step under `thickness`. A coarse march that stopped bisecting early would leave the crossing bracketed more loosely than a surface is thick, and every hit would then fail the thickness test — long-range reflections would vanish outright instead of thinning. A hit is rejected when the surface it landed on faces along the ray, because what is on screen there is that surface's far side. ## What the channel holds `ssr_out` is `@scene.reflection`: linear radiance in `.rgb`, and in `.a` the confidence — the edge fade, the range fade, how squarely the ray carried on into the scene, and `intensity`, multiplied — so `intensity` is how much of the trace reaches the picture and a miss is a zero the material reads as "the environment alone". The channel is cleared at the top of every scene render this feature does not run for, so such a frame reflects the environment alone too. The trace reads the light the previous frame ended with, so it runs on the lit channel alone (`debugChannel = 0`); a camera drawing a diagnostic pass is drawn lit first, unpresented, so the trace runs for where that camera stands, and the diagnostic reads the channel traced for it. The cutoff exists because a single ray describes a mirror: past it the lobe a rough surface gathers over is wider than one ray can stand in for, and the material keeps the prefiltered environment it already has.

# ssr_common The screen-space reflection passes' shared ground: the view-space reconstruction from depth, and the ray-to-screen projection the march steps along. Included with `#include "@builtin::systems.reflections.ssr_common"`.

# ssr_trace Marches a reflection ray through the depth buffer and reports where it hit. ## Includes - `ssr_common` ## Bindings | name | kind | |------|------| | `scene_color` | `texture2d` | | `scene_depth` | `texture_depth` | | `scene_normal` | `texture2d` | | `scene_material` | `texture2d` (`sample: uint`) | | `frame_cam` | `buffer` | | `ssr_params` | `buffer` | | `ssr_out` | `storage2d (rgba16f)` |

# 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.

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

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Bundle (asset type) A bundle is a composable, spawnable entity assembly— a saved entity hierarchy plus its components, sub-assets (meshes, textures, animations, materials, sub-bundles), and any nested data, packaged into a single addressable identity. Bundles are the engine's "prefab" primitive. There are **two ways** to bring a bundle into a scene — and the difference matters enormously for scene saving and live editing. See "How to spawn" below before you write anything. If you want one snapshot of a whole world / level, use a `.scene`. ## Where it lives - Source: `/zero/source/.../<Name>.bundle/` - Identity: `<Name>` (the `.bundle` suffix strips for use in identities, but the on-disk folder keeps the suffix). - Folder shape (container type — open child set): - `entity_template` — JSON of the entity hierarchy + components. **Required.** - `preview.png` — a rendered still of the assembled hierarchy, the bundle's persisted visual description. **Required.** Rendered when the bundle is staged (`zm add`) with its preview missing or stale, and by `generatePreviews`; it syncs, publishes, feeds image-based search, and gives browsers a thumbnail. - Anything else: meshes / textures / materials / animations / sub-bundles. Validator allows arbitrary additional files (`allow_unlisted: true`). ## How to create one Two paths, depending on whether you have an in-scene hierarchy or are authoring from scratch: ```luau -- From an existing in-scene entity: composes the given entity tree into a bundle. local bundle = asset.create("bundle", "<Name>",<entityProxy/id>) -- Or scaffold an empty bundle, then update it from an entity: local bundleRef = asset.create("bundle", "<Name>") bundleRef:update(entityId) ``` ## How to spawn ### 1. `Asset` component — live-linked (the canonical way) **This is the primary way to put a bundle into a scene that survives saving as an asset reference.** Spawn an empty entity, attach the `Asset` component, point it at the bundle: ```luau local car = entity.spawn("car_1") car.component.add("Asset", { source = "<bundleIdentity>" }) ``` What you get: - The bundle's hierarchy spawns as **temporary** children under the owning entity. They're real, addressable runtime entities, but they are NOT serialized into `scene.json` on save, only the Asset component and its entity is saved. - **Live editing of the bundle is supported.** When you edit anything inside the `.bundle/` (entity_template, meshes, materials, sub-bundles, components), every entity in the world carrying that `Asset` component automatically tears down its spawned children and rebuilds them from the new template — same frame, no restart, no manual reload. The `onAssetReload` hook in `Asset.component/init.luau` drives this. - **Per-instance overrides survive across reloads.** Move a spawned child, rename it, add/remove components on it, edit a component's public state — the changes land in the Asset's `public.diff` (a sparse delta keyed by the child's `original_id`) at save time and are replayed by `bundleRef:instantiate()` on next load. The bundle stays a single source of truth; per-spot tweaks ride on top. - **Stable child ids across reloads.** `public.idMap` records the `original_id → runtimeId` assignment on first spawn; on every subsequent spawn the same mapping is reused so cross-entity references (e.g. `SkinnedModel.skeletonRoot = "ent_xxx"`) stay valid. ### 2. `bundleRef:instantiate` — baked, no live link Resolve the bundle and instantiate it onto an entity — this spawns the children **without** the live-link plumbing the `Asset` component provides: ```luau local car = entity.spawn("car_1") asset.resolve("<Name>", "bundle"):instantiate(car) ``` What you get — and the trade-offs: - The children spawn as **regular** (non-temporary) entities. On the next `layers.active:save()`, the entire spawned hierarchy is serialized into `scene.json` verbatim. - **No live link to the bundle.** Editing the `.bundle/` after the fact has no effect on already-spawned hierarchies. The bundle was effectively consumed at spawn time. - Scene-save / restore round-trip works the same as for any other hand-authored entity tree. Use this path when you want a one-shot expansion of the bundle into permanent scene state (e.g. you're populating a scene's static layout from a parametric bundle and don't want a live link). You can convert a live-linked instance into a baked one explicitly via `Asset:bakeIntoScene()` — this drops the `Asset` component and promotes the temporary children to permanent scene entities. ## How it operates 1. **Registration.** Writing into a `.bundle/` folder indexes the asset with the container-category restore plumbing. 2. **Inner refs.** Component fields that reference assets inside the bundle use the `__ref` shape (`{ "__ref": "<guid>", "name": "...", "type": "..." }`). The asset registry resolves them at spawn time. 3. **Identity preservation.** The `.bundle` suffix stays in the identity for container types — `<Name>.bundle` resolves under that exact string, distinguishing it from any `<Name>.scene` at the same stem. 4. **Hot reload.** Saving `entity_template` (or any file in the bundle directory) fires the engine's per-asset content-changed hook, which calls `onAssetReload("source")` on every entity whose `Asset` component points at the bundle. Each carrier despawns its children and re-instantiates against the new template — typically next frame. ## Discovery - `asset.list("bundle")` — every registered bundle. - `asset.inspect("<name>")` — sub-asset catalog, source, this type README. - `ls /zero/source/<Name>.bundle` lists the files the folder holds. ## Authoring conventions - Prefer `bundle:update()` or `asset.create("bundle","<name>",entity)` over hand-authoring `entity_template`. The in-scene composer wires `__ref` shapes correctly and pulls in every transitively-needed asset. - Keep bundles focused — one prefab per bundle. If you have a "vehicle + driver + sound" assembly, split into three bundles and reference them from a scene rather than packing all three into one bundle. - Name child entities meaningfully — bundle interiors are inspectable, and stable IDs let other tooling (`entity_template` edits, animation hooks) find them. - Sub-bundles compose: a bundle's `entity_template` can `__ref` a child `.bundle/`. The asset registry resolves them transitively. ## Common pitfalls - **Confusing the two spawn paths.** `Asset` component = live link, reference-only scene save. `bundleRef:instantiate()` directly = baked, full hierarchy in `scene.json`. - **Inner-ref guids drift.** If you copy an `entity_template` from one bundle into another, the `__ref` guids may not resolve — re-compose from a live scene rather than copy-pasting JSON. - **The `.bundle` suffix is part of the identity.** This is the container-category convention. Don't strip it in reference strings. - **Live editing only fires for live-linked carriers.** Already-baked entities don't update when you edit the source bundle. ## Related types - `Asset.component` — the canonical mount point for a live-linked bundle. See its README for the `idMap` / `diff` machinery in detail. - `.scene` — owns a whole world's worth of entities; spawns bundles into itself via `Asset` components on per-spot entities. ## In the Inspector Selecting a bundle opens its **Contents** section, from the bundle's inspect detail: the template's node count, its root, the component types attached across it, a table of each renderable node's mesh and material, and a link to each of those meshes and materials.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Mesh Mesh asset. `data.zmsh` is the engine-native geometry payload (`renderer.mesh.encode`); consumers reference the asset's guid.

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).

# Texture Managed texture asset. `data.ztex` is the encoded payload the renderer uploads; compression settings live in `settings.yaml` (`texRef:setSettings({ ... })` to change one).