·
renderfeature · drop-in viewer
What it does
No description provided yet.
Interface
What this asset declares: the schema it conforms to, what it exposes, and the rendered structured payload.
conforms to
zero/source-extract/v2UI motion / change debug view — the UI analogue of the motion_vectors pass. `capture pass=ui_motion` frame-differences two engine-maintained images of the content UI: this frame's (`@texture.__ui_motion_current`) against last frame's (`@texture.__ui_motion_previous`). A static region is identical in both and reads BLACK; a region that moved, recoloured, changed opacity or scale differs between the two and is coloured by the magnitude of its change, through a black->blue->cyan->green->yellow->red heat ramp. So "is this UI animating, and where?" becomes a question you answer by looking instead of by reasoning. The two UI images are maintained by the engine on the present loop whenever a pass asks for them (this feature's compute pass does), so the diff always reflects the last two real frames. A compute pass reads both and writes the heat into a screen-sized target; a blit pass overwrites the scene colour with it. Both are gated to the "ui_motion" capture view's debug channel, so they cost nothing on the live viewport (channel 0) and draw only under a capture that selects the view.
render(ctx: ?) → void
| arg | type | description |
|---|---|---|
| ctx | ? |
teardown( ) → void
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# renderFeature
A **render feature** inserts custom GPU passes into the frame pipeline. The engine
provides one generic capability — a per-frame render-pass queue and a set of
pipeline-phase insertion points — and a feature is the authored Luau that decides
what passes to enqueue, and where, every frame.
## Authoring contract
A `.renderFeature` folder holds an `init.luau` that returns a feature module:
```luau
return {
setup = function(ctx) -- optional; runs once when the feature goes live
-- A "fragment" pass's `shader` names a POST EFFECT, not a `.shader`
-- guid directly — postprocess.add compiles the shader asset under
-- that name once, here. Enqueueing a name never passed to
-- postprocess.add runs the pass as a no-op every frame (the log
-- reads "effect '<name>' not compiled — pass skipped").
postprocess.add("my_effect", asset.resolve("my.shader.guid", "shader"), { enabled = false })
end,
render = function(ctx) -- required; runs every frame
-- enqueue one or more passes. The spec shape depends on `kind` (see
-- "Pass kinds" below): this is a "fragment" pass (full-screen shader over
-- input textures); a mesh effect (outline, x-ray) is a "geometry" pass
-- with `material` + `select` (see "Geometry passes").
ctx.enqueue {
phase = "afterTransparent",
shader = "my_effect",
inputs = { src = "@scene.color" },
output = myRenderTargetGuid,
}
end,
teardown = function(ctx) end, -- optional; runs once when the feature is destroyed
}
```
Optional `materials/` and `shaders/` subfolders hold shader source the feature
constructs GPU programs from. A feature constructs its GPU programs (it does not
reference `.material` surface assets).
## `ctx`
Built fresh each frame and passed to `setup` / `render` / `teardown`:
| Field | Meaning |
|-------|---------|
| `ctx.enqueue(spec)` | Queue one render pass for the current frame. |
| `ctx.viewport` | `{ w, h }` — the **main viewport's** size in pixels. |
| `ctx.time` | Seconds since boot. |
| `ctx.frame` | Monotonic frame index. |
| `ctx.renderPath` | `"forward"` / `"deferred"` / … — branch passes on the active path. |
| `ctx.settings` | The feature's knobs as they stand this frame — see "Settings". |
## Settings
A feature declares the knobs it takes as `settings`, each a Field descriptor
with a default, the way a component declares its public fields:
```luau
local Fields = require("@builtin::modules.field")
local Field, NoSync = Fields.Field, Fields.NoSync
return {
settings = {
intensity = Field.number(1.0, NoSync, "How much of the effect reaches the image."),
quality = Field.enum({ "low", "high" }, "high", NoSync, "How many samples the pass spends."),
},
render = function(ctx)
local s = ctx.settings -- { intensity = 1.0, quality = "high" }, or what a caller set
...
end,
}
```
The engine holds one settings table per live feature — every declared default,
overridden by what it was handed — and passes it as `ctx.settings` on every
`setup` / `render` / `teardown`. A feature reads its knobs there and nowhere
else, so any caller tunes any feature by name:
```luau
local h = renderer.feature.create(ref, { settings = { intensity = 0.5 } })
renderer.feature.configure(h, { quality = "low" }) -- lays over the rest
renderer.feature.settings(h) -- { intensity = 0.5, quality = "low" }
renderer.feature.find(ref) -- the live handle, or nil
renderer.feature.schema(ref) -- the declared knobs, unrun
```
A knob the feature does not declare, or a value of the wrong shape, is refused
by name. A scene authors its features on one `RenderFeatures` entity — a list
of features, each with its settings — which adopts a feature already live
rather than stacking a second, and takes every one down on disable and destroy.
`render` runs **once per frame**; the passes it enqueues run **once per render
target** drawn that frame — the live viewport, every offscreen capture, every
RTT camera — each at its own resolution. So `ctx.viewport` is the main
viewport's size, not the size of the target a pass ends up drawing into. Size a
full-screen scratch RT with `screen = true` and let the engine track the drawn
target (see "Screen-sized targets") rather than deriving it from `ctx.viewport`.
## Screen-sized targets
`renderer.texture.create { screen = true }` marks a feature RT as full-screen:
before each render target's feature passes, the engine resizes it to that
target's resolution. Create it once — the engine owns its size from then on:
```luau
myRt = renderer.texture.create {
width = ctx.viewport.w, height = ctx.viewport.h, -- initial size only
screen = true, format = "rgba16f", name = "my_effect",
}
```
A target that holds a picture of the scene is `rgba16f`, which is what the scene
target itself carries: linear light with headroom above the display's white and
no 256-step floor under a dark gradient. Omitting `format` on a screen-sized
target asks for the same thing. `format = "rgba8"` is for a mask, a weight or an
occlusion term, where 0..1 is the whole range — hand one of those back over
`@scene.color` and the frame loses every highlight and bands every gradient, and
the engine says so in the log.
`screenScale` (default `1.0`) takes a fraction of the drawn target's resolution,
for a scratch that runs below composite resolution (a half-res blur passes `0.5`).
A screen-sized RT is what makes a full-screen effect composite correctly at any
resolution. Deriving the size from `ctx.viewport` instead pins the RT to the main
viewport, and every differently-sized render target then composites a mismatched
scratch — the scene scaled into a corner with the rest black.
`screenSpace` names WHICH image a screen-sized RT follows:
| value | what it tracks |
|---|---|
| `"scene"` (default) | the scene render target, at whatever resolution the render scale asked for. Resized before EVERY render target's feature phases — the main frame and each offscreen one — and cleared to transparent before an offscreen render, so one sink never reads what another left behind |
| `"composite"` | the image the post-scene phases draw into. Resized on the presented frame only, and never cleared for an offscreen render, since none of those phases run there |
The two carry the same size until the render scale drops below 1. From there,
while the renderer presents the viewport itself, the scene reaches the display's
resolution through an upscale that runs before `afterScenePost` — so a
composite-space RT is the display's size while a scene-space one is the smaller
rasterized frame. Under a UI viewport panel the panel draws the scene target at
its own rect, nothing upscales beforehand, and both spaces carry the scene's
size.
A scene-space target is scratch: whatever a pass does not rewrite this render is
transparent black. A composite-space target survives an offscreen render
untouched, but it follows the presented frame alone.
## History targets
An accumulation across frames (temporal antialiasing, a temporal denoiser, any
pass that reads what it wrote last time) lives in a history target:
```luau
history = renderer.texture.create {
width = ctx.viewport.w, height = ctx.viewport.h, -- initial size only
history = true, format = "rgba16f", name = "my_accum",
}
-- in render(ctx):
ctx.enqueue {
kind = "compute", program = myResolve,
inputs = { scene_color = "@scene.color", accum_previous = history.previous.guid },
buffers = { accum_state = history.state },
storage = { accum_out = history.guid },
phase = "afterLighting",
}
```
The passes a feature enqueues run once for every view the frame draws (the
viewport, each render-to-texture camera, each capture), so an accumulation has
to be one per view. A history target keeps one pair of images per view, sized to
that view: for the length of a view's render `history.guid` names the image the
render writes and `history.previous.guid` the image the same view's previous
render wrote. Another view never resizes, clears or overwrites them, and a
view's images are freed when it stops drawing. It follows `screenSpace` and
`screenScale` like any screen-sized target; a composite-space one is kept for
the viewport, the one view that draws the post-scene phases.
Before each render of a view the engine writes `history.state`, one
`vec4<f32>` a pass binds through `buffers`:
| field | holds |
|---|---|
| `x` | 1 when `previous` holds this view's previous image; 0 on the view's first render, its first after a camera cut or a change of size, or after a render of the view that ran without the target, and `previous` then reads transparent black |
| `y` | how many renders in a row have carried the history |
| `zw` | this render's sub-pixel projection offset, in pixels (`renderer.setProjectionJitter`) |
`renderer.setProjectionJitter` is the matching per-view sample sequence: every
view walks it by its own count of renders, so the sequence a temporal pass
expects is the one each view's renders sampled.
## Pass phases
`enqueue` runs a pass at a named pipeline boundary — a real seam between the
scene's discrete passes — ordered within a phase by `order`. Each phase is the
point where the scene colour holds a specific, nameable state:
| Phase | Scene colour there |
|-------|--------------------|
| `afterDepthPrepass` | the visibility raster written: `@scene.depth` holds this frame's complete opaque depth, and `@scene.motion` its opaque motion, before anything shades. Scene colour is not yet drawn; `@scene.colorHistory` holds the previous frame's lit colour, and the deferred g-buffer the previous frame's surfaces (`readsPrevious`) |
| `afterShadows` | shadow maps populated; scene colour/depth not yet drawn |
| `afterSky` | sky only; depth empty |
| `afterOpaque` | opaque drawn, before transparents. `@scene.depth` (and the deferred G-buffer) are populated. Forward: lit opaque. Deferred: opaque is in the G-buffer, so the colour is still sky only until the composite (use `afterOpaqueLit`) |
| `afterOpaqueLit` | the lit opaque scene, still before transparents, on **both** paths — the forward opaque draw, or the deferred lighting composite. The background a refractive or transmissive surface samples: the one phase whose colour holds what is behind such a surface without holding the surface itself |
| `afterTransparent` | transparents drawn, before the OIT composite |
| `afterLighting` | deferred-lighting + OIT composite done — fully lit, final geometry on **both** paths |
| `afterScenePost` | scene-layer post (DoF/MB/…) done, before UI |
| `afterUI` | scene + UI composited |
| `afterPost` | all-layer post done — the final image, before present |
The last three are the post-scene phases, and they work on the COMPOSITED image:
`@scene.color` there is the target the UI lands on, not the scene render target.
`@scene.depth` and `@scene.motion` still bind — they are the scene's own buffers
for the frame just drawn, which is what lets a pass at these phases reproject the
composite it is handed — but they keep the SCENE's resolution. Whenever the
render scale is below 1 on the presented frame, that is smaller than
`@scene.color`, so a pass here maps between the two by uv rather than by texel
index, and takes its own output size from the target it writes.
The `@scene.*` inputs (`@scene.color`, `@scene.depth`, …) bind the live frame
buffers; the deferred g-buffer channels (`@scene.normal`, `@scene.shaded`, …)
resolve only on the deferred path. Before the pass that shades has drawn — at
`afterDepthPrepass` — a g-buffer channel holds the previous frame's surfaces,
and a pass reading it there names the slot in `readsPrevious`
(`readsPrevious = { "scene_normal" }`); one that does not is held back rather
than handed a stale normal. `@scene.colorHistory` is the lit colour the target's
previous render ended with, kept by the engine per render target and never
cleared by a frame: what a pass tracing at `afterDepthPrepass`, against this
frame's depth, takes its light from — reprojected through the previous
view-projection `@frame.camera` carries. A capture drawn once, or a camera drawn
again after a pause, is drawn lit first when a pass reads the history, so its
first frame holds one.
Every `@scene.*` channel, what it holds, its format, the phase it is first
valid from, and the other names it answers to:
| Name | Holds | Format | Valid from | Also named |
|---|---|---|---|---|
| `@scene.color` | the scene's lit colour; the display composite at a post-scene phase | the scene target's format at a scene phase, the display composite's at a post one | every phase | — |
| `@scene.depth` | opaque depth, reversed (1.0 near, 0.0 far/empty sky) | `Depth32Float` — binds through a `texture_depth` compute slot, not `texture2d` | `afterDepthPrepass` on | — |
| `@scene.motion` | screen-space NDC velocity since the previous frame | `Rg16Float` | `afterOpaque` on | — |
| `@scene.normal` | world-space normal + the per-pixel surface-flag field | `Rgb10a2Unorm` | deferred path, `afterOpaque` on (previous frame's before — declare `readsPrevious`) | — |
| `@scene.shaded` | what a surface SENT — its shaded colour, linear and scene-referred | `Rgba16Float` | deferred path, `afterOpaque` on (previous frame's before) | `@scene.albedo` |
| `@scene.material` | what a surface IS — base colour (RGB565) + metallic + perceptual roughness | `Rgba8Uint` | deferred path, `afterOpaque` on (previous frame's before) | `@scene.mr` |
| `@scene.emissive` | radiance a pass stamped on the surface, added at the composite | `Rgba16Float` | deferred path, `afterOpaque` on (previous frame's before) | — |
| `@scene.ao` | scene occlusion a feature wrote, read back by shading | `Rgba8Unorm` | every scene phase (cleared at the top of the scene render) | — |
| `@scene.reflection` | traced reflection radiance (`.rgb`) + confidence (`.a`) | `Rgba16Float` | every scene phase (cleared at the top of the scene render) | — |
| `@scene.colorHistory` | the lit colour the target's previous render ended with | `Rgba16Float` | every phase | — |
| `@scene.lights` | the punctual-light storage buffer: 64 light entries of twelve vec4s each (the light, then its punctual shadow record), followed by the virtual shadow map's region. A loop runs over the first `@frame.camera[4].w` entries, the lights in use; the buffer's length counts the shadow region too, so `arrayLength` does not size a light loop | storage buffer | every phase | — |
| `@scene.environment` | the reflection-probe cube array | texture cube array | scene phases only | — |
| `@scene.environmentSampler` | the filtering sampler for `@scene.environment` | sampler | scene phases only | — |
| `@scene.reflectionProbes` | the environment buffer: the probe blend data naming which probe reaches a point, then the irradiance light-probe volumes | storage buffer | scene phases only | — |
The rendering and ray-tracing guides (`guides { path = "topics/rendering" }`,
`guides { path = "topics/raytracing" }`) point here rather than repeating this
table.
**Two g-buffer channels describe the surface, and they answer different
questions.** `@scene.shaded` is what a surface SENT — the colour the geometry
pass shaded it to, linear and scene-referred, so a surface lit above the
display's peak reads above 1 there. `@scene.material` is what the surface IS:
the base colour it reflects, its metallic and its perceptual roughness, each in
[0, 1] and each independent of how brightly the surface happens to be lit. A
pass that multiplies incoming light by a reflectance — a bounce multiplier, a
Fresnel tint, an ambient floor — reads `@scene.material`; a pass that filters
the picture reads `@scene.shaded`.
`@scene.material` is an `Rgba8Uint` channel packing all three into 32 bits, so
its slot declares `sample: uint` and the module unpacks it:
```yaml
# bindings.yaml
- { name: scene_material, kind: texture2d, sample: uint }
```
```wgsl
#include "@builtin::shaderModules.gbuffer_material"
let m = zero_gbuffer_material(scene_material, coord);
let bounce = incoming * m.base_color;
```
`@scene.albedo` is another name for `@scene.shaded` (the SHADED lit colour) and
`@scene.mr` for `@scene.material` (the material channel). The engine logs the
substitution once per name, naming the canonical one to write.
`@scene.motion` carries screen-space velocity: the NDC displacement each pixel's
surface underwent since the previous frame, so a still surface under a still
camera reads `(0, 0)`. Opaque geometry contributes it on both render paths:
the visibility raster writes it for every surface it records, and an opaque
surface whose depth state the raster cannot express writes its own where it
draws. A moving entity, a moving camera and an animated pose all reach it in
the viewport; transparents, particles and sky carry none. A surface a
material's `vertex()` hook displaces carries the displacement's own velocity. A render target's own camera and a
capture keep no view history, so velocity there is the entity's motion with no
camera term.
`@frame.camera` is a reserved **buffer** input carrying the camera CURRENTLY
being drawn: 10×`vec4<f32>` = the inverse view-projection (columns `[0..4)`,
column-major) + camera world position (`[4].xyz`) + the previous render's
view-projection (columns `[5..9)`), which projects a point into the picture
that render left. A compute pass declares a
`buffer` binding and binds it via `inputs = { name = "@frame.camera" }`, then
reconstructs a pixel's world position from `@scene.depth`:
```wgsl
let inv_vp = mat4x4<f32>(cam[0], cam[1], cam[2], cam[3]);
// ndc.z is the `@scene.depth` sample itself. Scene depth is reversed — 1.0 is
// the near plane, 0.0 the far plane and empty sky — and this matrix inverts
// that same range, so a sample goes in unmodified.
let wh = inv_vp * vec4<f32>(ndc, 1.0);
let world_pos = wh.xyz / wh.w;
```
Like `@scene.*`, the engine resolves it **per render target** — so the same pass
reconstructs against the live viewport's camera on screen and against an
offscreen capture's / RTT camera off screen. (Pack a camera matrix into your own
buffer instead and the offscreen render reconstructs against the wrong camera.)
> Render-feature passes run in the main viewport render **and** in offscreen
> captures / render-to-texture, each against its own camera. The `capture` tool's
> `source = "position"` / `"entity"` therefore run the pass queue too; using
> `@frame.camera` is what keeps those captures matching the live viewport.
### The environment
A compute pass reads the scene's captured surroundings — the reflection-probe
cube array, its sampler and the environment buffer (the probe blend data, then
the irradiance light-probe volumes) — through three reserved inputs, bound to
bindings of the shapes group(0) binds them in:
```yaml
bindings:
- { name: environment_map, kind: textureCubeArray }
- { name: environment_sampler, kind: sampler }
- { name: zero_environment, kind: buffer, access: read, element: ZeroEnvironment, array: false }
```
```luau
inputs = {
environment_map = "@scene.environment",
environment_sampler = "@scene.environmentSampler",
zero_environment = "@scene.reflectionProbes",
}
```
Named like that, `#include "zero::environment"` in the shader resolves the
environment at a world point along a direction — `zpbr_sample_environment(world_pos,
dir, lod)`, the probes whose radius reaches the point blended by rank and
proximity, each through its proxy volume, and the sky under them — exactly as a
material's environment term does, so a reflection a pass draws and one a
material draws agree about the room they are in. The three bind at the scene
phases; a post or UI phase carries none. A `textureCubeArray` binding takes
`@scene.environment` alone, and a fragment pass has no slot of that shape.
## Pass kinds
`enqueue` runs one of five kinds (the `kind` field; default `"fragment"`):
- **`"fragment"`** — a full-screen shader over input textures. The program is a
GPU **material** (or `shader`) the feature constructed; `inputs` bind live
textures (`@scene.*` or RT guids), `output` is the target RT (omit = the
phase's default scene target). Post-process, blur, edge effects.
**Writing named G-buffer channels (`outputs`).** Instead of the single `output`
RT, a fragment pass may declare an `outputs` array — one or more targets, each a
named engine channel (`@scene.shaded` / `@scene.normal` / `@scene.emissive` /
`@scene.color`) or an RT guid — each with its own blend mode:
```luau
ctx.enqueue {
kind = "fragment",
shader = myShaderKey,
outputs = {
{ target = "@scene.shaded", blend = "under" }, -- premultiplied dst-over-src
{ target = "@scene.emissive", blend = "additive" }, -- one fullscreen pass, two targets (MRT)
},
phase = "afterOpaque", -- deferred: G-buffer filled, before the lighting composite
}
```
Blend modes: `"replace"` (overwrite), `"alpha"` (source-over), `"additive"`
(sum), `"under"` (premultiplied dst-over-src — accumulates coverage-weighted
contributions). A `@scene.*` channel resolves only where it exists (the deferred
G-buffer at a pre-composite phase); a pass whose targets are all unavailable at
its phase is skipped (logged). `output` + `blend = true` remains the shorthand
for a single alpha-blended target. The shader's returned colour is written to
every target in the set.
A fragment shader returns `vec4<f32>`, so the channels it can target are the
float ones. `@scene.material` (also named `@scene.mr`) is
`Rgba8Uint`, which binds as `uint` — naming it as an output is refused by
name, with the channel's format and class in the log, and the rest of the
frame draws. A fragment pass's `inputs` reads through the same fixed float
slot, so naming `@scene.material` there is refused the same way; a compute
pass reads that channel through a `sample: uint` slot instead.
**What a pass with no `inputs` samples.** A fragment pass that declares no
`inputs` reads `@scene.color` — the shape of an effect that filters the scene
image. A pass that names `@scene.color` among its own `outputs` samples a 1x1
transparent texel instead, because the scene colour is that pass's render
target and one texture is a colour attachment or a sampled resource in a render
pass, never both. Declare `inputs = { src = "@scene.color" }` and write an RT
to read the scene image and write somewhere else in one pass.
- **`"compute"`** — a workgroup dispatch (`shader`, `storage`, `buffers`, `dispatch`;
see "Compute passes").
- **`"geometry"`** — draw scene geometry with a constructed pipeline. The program
is a **material** the feature built (`renderer.material.create`); the engine
draws the scene's render-objects with that material's pipeline + uniforms.
- **`"draw"`** — rasterize the feature's OWN geometry: `geometry` names a buffer
created with `usage = { "vertex" }`, `storage.index` one created with
`usage = { "index" }`, and `select` the one entity whose transform and
material the draw lands through. `params[0]` is how many indices to submit —
or name a buffer under `storage.indirect` (created with
`usage = { "indirect" }`, holding a `DrawIndexedIndirectArgs` block: index
count, instance count, first index, base vertex, first instance) and the count
comes from the GPU instead, so a compute pass that compacts geometry pays only
for what it kept and nothing waits on a read-back. `first_instance` must be 0;
the engine resolves the entity's per-instance data another way, because a
non-zero one needs a device feature WebGPU does not guarantee.
- **`"splat"`** — rasterize a compute buffer of particle records as instanced
camera-facing billboards into feature RTs (see "Splat passes").
### Geometry passes
A geometry pass re-draws the scene's meshes with a material you supply — the
generic primitive for mesh-space effects (the engine names none of them):
```luau
ctx.enqueue {
kind = "geometry",
material = myMaterial, -- the HANDLE renderer.material.create
-- returned (or its registry-key string)
geometry = "@geometry.opaque", -- which drawables: "@geometry.opaque" |
-- "@geometry.transparent" | "@geometry.all"
select = { entityA, entityC }, -- OPTIONAL: restrict to these entities
-- (entity refs); omit = every matching mesh
phase = "afterLighting", -- afterLighting = lit scene + valid depth
}
```
`select` restricts the draw to the given entities — the per-instance signal that
turns a whole-scene pass into a chosen-meshes effect. The **material** decides how
those meshes are drawn; you control three things:
- **Pipeline render-state.** `renderer.material.create` takes a `render` block —
`cull` (`back`/`front`/`none`), `depthWrite` (bool), `blend`
(`opaque`/`alpha`/`additive`) — so the pass can rasterize differently from the
surface pass:
```luau
local myMaterial = renderer.material.create({
shader = myShaderKey, -- a .shader you authored (identity, not guid)
render = { cull = "none", depthWrite = false },
properties = { outline_color = { 1, 0.4, 0, 1 } }, -- seed the shader's uniforms
}, "my_pass_mat") -- pass `myMaterial` (or "my_pass_mat") as the pass `material`
```
- **The shader.** A geometry `.shader` is a surface shader: author `fn vertex(v:
VertexData) -> VertexData` to move vertices (object-local `v.position` /
`v.normal`) and `fn fragment(input: FragmentData) -> vec4<f32>` for the colour.
- **Its properties.** A shader reads ONLY the uniforms IT declares in
`properties.yaml`, via `material.<yourProp>`. Referencing a field it didn't
declare (e.g. a StandardMaterial `material.base_color`) fails to compile and the
mesh renders **magenta** — declare the property or use a constant.
What effect those three produce (outline, x-ray, wireframe, highlight, …) is
yours to design — the engine just draws the selected geometry with your pipeline.
### Compute passes
A compute pass dispatches a `.computeShader` program over a workgroup grid:
```luau
ctx.enqueue {
kind = "compute",
program = myComputeShader,
storage = { outTex = myStorageRtGuid }, -- slot -> storage-texture RT guid
buffers = { particles = "my_particle_buf" },-- slot -> named compute buffer
inputs = { camera = "@frame.camera" }, -- slot -> @frame.*/@scene.* buffer
dispatch = { x = 64, y = 1, z = 1 },
}
```
**`dispatch` is optional.** Omit it and the pass is dispatched over what it
WRITES: a grid covering its first `storage` texture, at the `@workgroup_size` the
shader's entry point declares. With a screen-sized storage target that grid
tracks the render target being drawn, so a screen-space effect covers the live
viewport, an offscreen capture and an RTT camera without the feature knowing any
of their resolutions:
```luau
ctx.enqueue {
kind = "compute",
program = myComputeShader,
inputs = { scene_color = "@scene.color", cam = "@frame.camera" },
storage = { outTex = myScreenSizedRt.guid }, -- screen = true
phase = "afterLighting",
}
```
State an explicit `dispatch` for a grid that is not one thread per output texel
(a reduction, a particle sim), or when the shader's `@workgroup_size` is an
override/const expression the engine cannot read.
Each WGSL storage-buffer binding in the shader resolves its bound slot in this
order: an explicit `buffers` mapping (the handle a buffer's owner holds, or a
name), then `inputs` (`@frame.camera` / `@scene.lights` /
`@scene.reflectionProbes`), then — when a slot has neither — a buffer whose
engine-side name equals the slot's own name. `buffers`
is the seam a pass binds through: the buffers a shader works over are the ones
handed to it, whatever each is called. `storage` binds storage TEXTURES (RT
guids) the same way, one map per resource kind.
### Splat passes
A splat pass draws every record of an f32 buffer as a camera-facing billboard —
the raster primitive behind screen-space particle surfaces (the `fluidSurface`
system is built entirely on it):
```luau
ctx.enqueue {
kind = "splat",
phase = "afterLighting",
output = depthRt.guid, -- or `outputs` for the thickness+color MRT
splat = {
buffer = "my_particles", -- compute-buffer name
stride = 12, -- floats per record
posOffset = 0, -- float offset of the position
count = 200000, -- records to draw
radius = 0.3, -- world particle radius
channel = "depth", -- "depth" | "thickness" | "sprite" | "gaussian"
velOffset = 4, -- optional: velocity → screen-space stretch
stretch = 0.04, -- seconds of motion elongating the billboard
colorOffset = 8, -- optional (thickness): + per-particle RGB → MRT
weightOffset = 7, -- optional (sprite): per-particle intensity
minY = -60.0, -- records below this y collapse (parked/dead)
maxRadiusPx = 120, -- optional: cap on the projected pixel radius
},
}
```
The `"gaussian"` channel draws the engine's packed splat records — what
`renderer.splat.components` decodes a `.spz` or `.ply` capture into — as
elliptical-weighted-average Gaussians, and takes fields of its own:
```luau
splat = {
buffer = "cloud_records",
stride = 6, -- the packed record is six u32 words
posOffset = 0,
count = 1200000,
radius = 1.0, -- multiplies each splat's stored scale
channel = "gaussian",
orderBuffer = "cloud_order", -- back-to-front permutation; "over" needs one
shBuffer = "cloud_sh", -- optional: quantized higher-order SH
shStride = 24, -- u32 words of SH per record
shDegree = 3,
transform = model, -- object -> world, column-major, 16 floats
prevTransform = prevModel, -- where `transform` stood last frame
opacityScale = 1.0,
}
```
`transform` places the cloud: each Gaussian's covariance is conjugated by its
upper-left 3×3, so a non-uniform scale shears the cloud the way it shears a mesh.
`prevTransform` plus a second entry in `outputs` makes the channel write an MRT
pair — the colour into the first target, and the screen-space displacement each
splat underwent between the two placements into the second, premultiplied by the
same alpha the colour composites under. That second target therefore resolves to
`(coverage-weighted mean displacement, coverage)`, which is what folds a moving
cloud into `@scene.motion`. Naming one target, or leaving `prevTransform` out,
renders the colour alone.
The other three channels write different fragments: `"depth"` writes nearest-surface
linear view depth (R32Float, hardware-depth-tested on the target's own depth
buffer), `"thickness"` accumulates additive optical thickness (with
`colorOffset` and a two-entry `outputs` list it also accumulates
thickness-weighted color into the second target), and `"sprite"` accumulates a
soft additive disc scaled by `weightOffset`. Every channel discards fragments
behind opaque scene geometry by sampling the scene depth at the fragment's own
NDC. `maxRadiusPx` scales down billboards whose projected major radius would
exceed that many pixels, so particles crossing the near plane stay
droplet-sized instead of filling the screen. Targets clear at the pass;
`blend = true` on the spec loads them instead to accumulate over a prior
splat pass.
`renderer.feature.create(featureRef)` instantiates a feature and returns a live
handle (`featureRef` may be an `AssetRef<renderFeature>` or its identity string).
The handle appears under `/zero/runtime/generated_features/<guid>/`. Re-creating
the SAME feature asset replaces the live one (hot-reload after editing
`init.luau`) rather than stacking a duplicate.
- `renderer.feature.list()` → `{ {guid, identity} }` for every live feature.
- `renderer.feature.destroy(handleOrGuid)` (or `renderer.destroy(handle)`) tears
one down — by handle OR by guid string, so you can stop a feature even after
losing its handle (e.g. across separate `execute` calls).
## In the Inspector
Selecting a render feature opens its **Feature** section: whether the feature runs in this session, an Enable or Disable action, and its settings as typed controls. While it runs, the controls hold its live values and an edit reconfigures the running feature (`renderer.feature.configure` checks it against the schema first). Those edits are session state: they change the running feature only, they are not undoable (Ctrl+Z never reaches them), and Disable or a restart ends them; the feature's declared defaults are what the next Enable starts from. While it does not run, the controls show the declared defaults, read-only, and a write reaching it then is refused. A feature enabled, disabled or reconfigured from a script shows in the section as it happens. A feature that declares no settings says so.
▲ 0↑ born
▲ 0↑ born
# assetType (asset type)
An asset type says what a kind of asset is: the files an asset of the kind is
made of, the code that gives it behaviour, the interface a person uses to work
with it, and how it is found, pictured and checked. A `<typename>.assetType/`
folder declares a type called `<typename>`, and every `<name>.<typename>/`
folder is an asset of it. `assetType` is itself a type, so a type is an asset
like any other: it is created, versioned, installed and contributed the same way.
## Making a type
`asset.create("assetType", "<typename>")` scaffolds a type. The type registers
the moment its folder is written, anywhere under `/zero/source/`, and from then
on `<name>.<typename>/` folders are its assets. An asset of a type that is not
registered yet is not an asset, so make the type first.
A type folder is a root: `~.x` in any file inside it names the type's own `x`,
wherever the type is installed. Keep the type's whole implementation inside its
folder and reach it that way.
What a type folder must hold is set by this type's own `type.yaml`, the same way
every type's `type.yaml` sets what its assets hold. `asset.validate` on a type
reports anything missing, and the scaffold produces a folder that passes.
## What sets your type's schema (`type.yaml`)
`type.yaml` is the structural contract every asset of the type is checked
against. The keys below are the ones the engine reads; a key not listed here is
ignored.
| Key | What it controls |
|---|---|
| `suffix` | The folder suffix of the type's assets. Defaults to `.<typename>`. |
| `primary` | The file or files that are the asset's content: what the asset resolves to when it is used. |
| `entry_files`, `primary_aliases` | Further files that load as the asset or share its identity. |
| `is_container` | Whether the suffix stays in the identities of what the asset holds. |
| `is_opaque_walker` | Whether a walk of the tree stops at the asset and registers only its primary. |
| `plural_dir`, `classify_exts` | Loose files in a folder of this name, or with these extensions, are assets of the type. |
| `is_text_default` | Whether the asset's files are text unless stated otherwise. |
| `broadcasts_subassets` | Whether assets nested inside an asset of the type are found by their own short name. |
| `root` | `true` makes every asset of the type a root, so `~.x` inside one names that asset's own `x`. |
| `contract_ref: { field, category }` | A key of the primary file that names another asset the asset is built on. |
| `files: { required, optional }` | The files an asset holds (below). |
| `allow_unlisted` | `false` reports every file the type does not declare. |
| `aliases_from: [{ file, key }]` | Further names an asset answers to, read from its own files. |
| `settings:` | Typed per-asset settings (below). |
| `inspector:` | The interface people use for the type and its assets (below). |
| `preview:` | How an asset is pictured (below). |
| `references:` | Names of other assets the type's files carry (below). |
| `indexing:` | What search reads for each asset (below). |
| `describe:` | How a missing description is generated (below). |
### The files an asset holds
Each entry under `files.required` or `files.optional` is
`{ path, kind: file | folder, one_of_group?, content? }`. `*` in a path matches
within one segment. Entries that share a `one_of_group` are satisfied by any one
of them. `content` lists checks on the file's bytes:
| Check | Passes when |
|---|---|
| `non_empty` | the file has content |
| `json_field { key, type?, non_empty?, accept? }` | the JSON holds the key (a dotted path) with that shape |
| `yaml_field { key, type?, non_empty?, accept? }` | the same for YAML |
| `described { keys?, headings?, message? }` | the file says what the asset is (see "Ask your assets to say what they are") |
Each check takes a `message`, which is what the author is told when it fails.
### Settings
`settings: { values, schema: { type | instance, export? } }` gives every asset
typed settings. `values` names the file an asset's values live in; `schema.type`
declares one schema for the whole type, and `schema.instance` names a file each
asset declares its own in. `asset.create` writes the resolved values, and a write
to the values file reaches `onChange` with what changed.
## The human side (`inspector.luau`)
A type is used by people through its Inspector, and without one the type is
usable only from code. The Inspector is the type's interface for a person: for a
procedural graph it is the graph editor, for a kit it is the tracking view of
what the kit holds and what is still missing. Writing it is part of writing the
type.
`inspector: { type, instance? }` in `type.yaml` names the files. `type` is the
interface for the type itself and for its assets; `instance` names a file an
asset may ship to add its own. Each returns:
```luau
return {
sections = { { id = "graph", title = "Graph", build = function(ctx) ... end } },
replace = { contents = { ... } }, -- replace a default section by id
order = { "graph", "contents" }, -- section order
}
```
`build(ctx)` receives the asset and builds the section. A section's `title`, and
the text its rows carry, is a string or an `i18n.text` value read from a catalog
(`i18n.text("inspectors.mesh.title")`), which follows the editor's language. `asset.create("assetType",
...)` scaffolds a working `inspector.luau` to start from. `asset.validate` on a
type that names no inspector, or names one that does not load, reports it.
## Say what your type is for (`about.yaml`)
Every type carries an `about.yaml` that says what the type is for, in three
plain-language texts:
```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, in the words a game maker uses. Up to 800 bytes.
- **`function`** is how it works today: what an asset of it is made of and what the engine does with it. Up to 1500 bytes.
- **`usage`** is what a person or an agent does with one. Up to 1200 bytes.
Write about the type as a whole, not one asset of it, and say what it does now.
Agents read these texts to learn when to reach for the type and how; people
searching find the type by them. The scaffold starts each text with
`[[describe]]` and a note on what to write; a text that still starts that way
counts as not written. `services describe` can write them.
They show up in `asset.inspect` as `detail.about`, in
`assetTypeRef:getAbout()`, at the end of the type's `types/<typename>` guide,
and at the top of the type's Inspector.
## Ask your assets to say what they are
A type can require each asset to carry a description: a file, written by the
author or generated, saying what the asset is and what it is for. Declare it with
a `described` check:
```yaml
files:
required:
- path: "README.md"
kind: "file"
content:
- { check: "described", message: "Say what this widget is for and where it goes." }
```
A file that is missing, empty or still has a line starting with `[[describe]]`
fails the check, and so does a YAML file whose named `keys` are missing or over
their `max_bytes`, or a Markdown file missing a named heading. `asset.validate`
names the asset, and a push that carries it is refused with `message`.
`services describe` finds such assets and writes their descriptions.
`describe:` steers what is generated:
```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>"
```
An example is an asset of your type whose description is a true, written one,
never a placeholder and never the asset being described; with none, leave
`examples` empty. A type whose assets the model cannot perceive (a sound, a
motion) says so in `guidance`, and the description is drawn only from what the
asset's own files state.
Start the file unwritten in your `template/`: a heading and one line starting
with `[[describe]]`, never example content, which every new asset would carry
verbatim. A type whose assets say what they are through their own content (a
mesh, a texture) declares no check.
## The type's code (`behavior.luau`)
`behavior.luau` returns one table. These are the keys the engine reads from it;
anything else on the table is the type's own.
### What the type's assets can do
| Key | Shape | What the engine does with it |
|---|---|---|
| `ref` | `{ [name] = function(self, ...) }` | Every function becomes a method on every asset of the type: `ref:name(...)`. |
| `modules` | `{ [name] = require(".x") }` | Code the type's assets reach with `asset.containing(__FILE__).modules.<name>`. |
| `events` | an events schema | Events an asset fires. Readers subscribe through `ref.events.<name>:connect(...)`; the type fires them. |
| `refShapes` | `{ [method] = function(self) -> (typeExpr, source?) }` | The result type of a `ref` method for one particular asset (below). |
| `namePattern` | a Lua pattern | The names `asset.create` accepts for the type's assets. Default `^[A-Za-z][A-Za-z0-9_]*$`. |
| `derive` | `{ output, module, compute, fingerprint, matches?, required?, timeout? }` | A file computed from the asset when it is committed; a `required` one holds the commit until it lands. |
Some `ref` names mean the same for every type, and the engine calls them:
- **`instantiate(self, target?, opts?) -> (root, idMap)`**: puts the asset in a scene. Defining it is what makes the type scene-instantiable. Its return is a contract (below).
- **`inspect(self) -> detail`**: what `asset.inspect` reports for the asset beyond the common record (below).
- **`preview(self, opts)`**: renders the asset's picture; it wins over the type's `preview:` recipe.
- **`previewMaterial(self) -> { material }`**: the material a `surface` preview paints.
- **`saveDefinition(self)`**: writes the asset's in-memory edits back to its files in edit mode.
Some names are answered for every asset before the type is asked, so a `ref`
entry of the same name is never reached: `getSource`, `getBytes`, `getText`,
`exists`, `deps`, `canInstantiate`, `canPreview`, `preview` (which calls yours
when you define one), `meta`, `runtime`, `events`, `typeRef`, `modules`, and the
residency flags `has_backing_asset`, `has_runtime_changes`, `cpu_resident`,
`gpu_resident`.
### When the engine calls the type
| Hook | Signature | When it runs |
|---|---|---|
| `onCreate` | `(name, opts) -> { [path] = contents }` | On `asset.create`. Returns the files of the new asset, laid over the type's `template/`. Annotate `opts`: its type is the schema `asset.create` checks the caller's arguments against. A `""` key writes a single loose file. |
| `onReplace` | `(dest, files) -> files` | On an `asset.create` over an asset already at `dest`, after `onCreate`, so what the author added can be carried into the replacement. |
| `onRegister` | `(self)` | Once per asset, when it first registers: when the world loads, on a live `asset.create`, and when an asset arrives later (installed, pulled, synced). This is what makes an asset take effect the moment it is written. |
| `onChange` | `(ref, change)` | On every write to a file inside an asset of the type. `change` is `{ path, asset, type, kind, origin }`, plus `settings` and `settingsChanged` for a write to the settings values file; `kind` is `edited` or `seeded`, `origin` is `local` or `remote`. Filter on `change.path`. Writes to one asset arrive in order, each after the hook for the one before has finished, and the hook may wait on what it reads. A write the hook makes inside its own asset arrives later like any other, so keep the hook convergent. |
| `onDependencyChange` | `(ref, change)` | When a module the asset's code requires is re-run, or a name the asset carries starts resolving. `change.kind` is `dependency`. |
| `onDelete` | `(ref)` | When an asset of the type leaves the world: deleted, or the world it is in is swapped away. |
| `validate` | `(ref) -> { { code, message, severity?, path? } }` | On `asset.validate`, after the `type.yaml` checks, for the type's own rules. `severity` defaults to `error`. Runs on every push, so a type's rules hold at publish. A hook that fails reports `validate.hook_failed`. |
### Settings hooks
| Hook | When it runs |
|---|---|
| `settingsDefaults(name, opts, asked) -> table` | Once per `asset.create`, for values the schema's defaults do not give. |
| `settingsCorrections(values, name, opts) -> (corrections?, reasons?)` | On every settings write. A correction to a field the writer named refuses the write, giving the reason. |
| `settingsDerivedDefaults(values, explicit, changed)` | On a settings write, for fields derived from others. |
| `normalizeSettings(values, stored?)` | On every read and write, to map an earlier spelling of a field to the current one. |
| `settingsHealed(values, stored)` | On a read, to repair stored values. |
| `settingsSchemaProblem(schema, ref) -> string?` | When an asset's own schema is read; a returned string refuses the schema. |
`creationInputs` (`{ [opt] = true | selectorOpt }`) names `asset.create` options
that are inputs to the type rather than settings.
### Reloading
An edit to `behavior.luau` reaches existing assets with no restart.
## How an asset is pictured (`preview:`)
| `kind` | The picture is | The type provides |
|---|---|---|
| `instantiate` | the asset placed in the preview studio through its `instantiate` | `ref.instantiate` |
| `image` | a file the asset holds, fitted to the frame | `source: { files }`, the candidate files in order |
| `surface` | the asset painted on a mesh | `mesh`, and `ref.previewMaterial` |
| `custom` | whatever `ref.preview` returns | `ref.preview` |
```yaml
preview:
kind: surface
mesh: sphere
```
`angle: [yaw, pitch]` turns the camera. The studio owns the light, the backdrop
and the framing, so an asset pictures the same in every world. A type with no
`preview:` that defines `instantiate` still answers `ref:preview()`.
A picture is rendered when something asks to view it (the editor showing the
asset, `ref:preview()`), when previews are generated on request
(`assets.generatePreviews`), and when the asset is staged. An edit alone
renders nothing. The picture records what it was made
from, so a stale one is told from a current one.
## The names your type's assets hold (`references:`)
Where your type's own format or API carries the name of another asset, declare
it here:
```yaml
references:
keys: # a top-level key of the type's files that holds a name, or a table of them
- { key: "shader", type: "shader" }
args: # an argument of a call, counting from 1
- { call: "g:node", position: 2, type: "procNode" }
fields: # a field of the options table a call takes
- { call: "fx.beam", field: "material", type: "material" }
```
`type` is the category the name resolves in. `asset.declareReferenceKey`,
`asset.declareReferenceArg` and `asset.declareReferenceField` declare the same
from a script.
## What search reads (`indexing:`)
`indexing:` is how assets are found. Search reaches an asset only through what
its type's `indexing:` names, and adds nothing of its own. That includes you: an
asset indexed badly is one you cannot find later, when you are making something
else and need it. A type whose assets are never looked for says `indexing: none`.
```yaml
indexing:
data: # text, read from the asset's files
- role: identity
extractor: verbatim
source: { file: "README.md" }
- role: interface
extractor: symbols
source: { files: ["init.luau"] }
- role: implementation
extractor: verbatim
source: { files: ["init.luau"] }
content: # the picture
- role: identity
modality: image
source: { file: "preview.png" }
facets: # what a query filters and re-ranks by
file: ".metadata"
rigged: { type: bool, from: { components: { contains: SkinnedModel } } }
roughness: { type: number, filter: range, from: { file: "mat.yaml", field: "floats.roughness" } }
```
**Roles.** Each `data` and `content` entry has a `role`, and a query matches in
two slots:
- **`identity`**: what an asset is. For anything you look at, the picture; for anything else, the text that says what it is.
- **`capability`**: what it does and how it is made. `interface` (the signatures or shape a caller uses) and `implementation` (the body) both count as capability, and a type with code usually declares both.
Ask what a person would recognise an asset of the type by, and what it does, and
point each role at the file that says it. For text, that is the asset's
description: the file your template starts with a `[[describe]]` block, which the
author writes or `services describe` fills in (see "Ask your assets to say what
they are").
**`data`.** `extractor: verbatim` embeds a file's text as it is; `symbols` embeds
the declared signatures of code. `source` is `{ file }` or `{ files: [...] }`.
Never index a file name (`source: { field: name }`): one
or two words carry nothing to match.
**`content`.** `modality: image` embeds the picture itself, so a text query
matches what the asset looks like. A type whose assets are looked at makes the
picture its identity.
**`facets`.** What a query narrows and re-ranks the matches by. `file` is embedded
whole, so keys nobody declared in it are still found. Each further key is
computed for every asset and states a value for every one, including `false`: a
file can imply "not rigged" but never say it, and a query separates rigged from
unrigged only because the unrigged ones say `rigged: false`. A key is
`{ type: bool | number | enum, filter?: range, from }`, where `from` is
`{ file, field }` (a field of one of the asset's files, dotted for nesting),
`{ metadata: key }`, or `{ components: { contains | any_outside } }` (what the
asset's entities carry).
## What blocks a push
A push checks every asset it carries against its type. These refuse it:
- a required file that is missing, a `content` check that fails, a `described` file not written yet;
- an error from the type's `validate`.
Unlisted files and warnings do not. A `described` file blocks only a push that
changes the asset. When a push is refused, the message names each asset and what
it lacks. `world.publishBlockers()` and `zm status` read the same list without
pushing.
## Typing a result from the asset (`refShapes`)
A `ref` method whose result depends on the asset (one entry per child folder, per
row of a config, per control a map declares) can only be annotated as
`{ [string]: Thing }`, which accepts any key. `refShapes` states the result for
each asset instead: a function returning a Luau type expression for that asset,
and the module whose types the expression uses. Read the asset; never run it.
```lua
-- inputMap.assetType/behavior.luau
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)` is checked and `map.noexisting` is reported.
A per-asset type applies where the call site names which asset: a component
field whose default names it, or an annotation `AssetRef<"inputMap", "<identity>">`.
`asset.resolve(name, category)` carries only the category, and a name computed
at runtime carries nothing, so calls on those keep the declared return. The type
belongs to the call's result: index it there, or bind what you need from it
there, and the names stay checked.
`require("@builtin::assetTypes.assetType.shared.refShapes").published()` shows
what was published: `categories` (each type's method surface) and `returns`
(per-asset results by identity, then method). An identity missing from
`returns` was never published. Results are recomputed when an asset is written;
at most 64 assets of one type are read.
## Putting an asset in a scene (`ref.instantiate`)
A caller writes one piece of code against every instantiable type, so what
`instantiate` returns is fixed:
```lua
local Instantiable = require("@builtin::assetTypes.assetType.shared.instantiable")
M.ref = {
instantiate = function(self, target, opts)
local root = Instantiable.root(self, target, opts)
-- compose the asset under `root`, now
return Instantiable.result(self, root, idMap)
end,
}
```
**In.** `target` is the entity the asset lands under, or onto for a hierarchy
type; with none, the type spawns a new root. `position`, `rotation` (three
numbers in degrees, or a quaternion), `scale`, `name` and `temporary` mean the
same for every type: `Instantiable.root` applies them to a root you make,
`Instantiable.place` to one you adopt. Document any options of your own in the
hook's `--!arg` docs.
**Out.** `(root, idMap)`. `root` is the composed root, live when you return:
build synchronously, never defer to a component's `awake`. `idMap` maps each
original id to the spawned one, so a component that composes the asset again on
every load can pass it back in and keep references into the composition. Every
call goes through `Instantiable.result`, which refuses a root that is not live
and turns a missing `idMap` into `{}`.
## Inspecting an asset (`ref.inspect`)
`asset.inspect(ref)` builds a record every asset shares (`identity`, `name`,
`guid`, `source`, `typeName`, `typeDefinitionPath`, `scope`, `origin`,
`description`, `tags`), then calls `ref.inspect(self)` for the type's own
`detail`:
```lua
M.ref = {
inspect = function(self)
-- read the asset's own files, never runtime state: inspect works on an asset
-- that has not been compiled, uploaded or registered
return { --[[ what makes this asset what it is ]] }
end,
}
```
Without it, the record is the shared part alone, and an agent inspecting the
asset learns nothing of what it is. A hook that raises leaves `detail` empty and
sets `record.warning`.
## Discovery
- `asset.list("assetType")`: every registered type.
- `asset.inspect("<typename>")`: the type, its README and its `about.yaml` texts.
- `asset.resolve("<typename>", "assetType")`: the type itself.
▲ 0↑ born
# assetType.shared.settings
Resolves four questions about an asset's typed settings, all answered from its
type's `type.yaml` — nothing here is found by convention.
```lua
local Settings = require("@builtin::assetTypes.assetType.shared.settings")
-- or, from inside the assetType runtime:
local Settings = require("@builtin::assetTypes.assetType.shared").settings
```
## Where does a type's schema live?
`type.yaml` names it in a `settings:` block:
```yaml
settings:
values: "settings.yaml" # where an instance's own values live
schema: { type: "settings.luau" } # one schema for every asset of this type
```
or, for a type whose settings differ per instance (an importer):
```yaml
settings:
values: "settings.yaml"
schema: { instance: "settings.luau" }
```
or, for a type whose schema is a table its instance's own source declares and
whose values live elsewhere (a component: its `public` fields, valued on each
entity it is on):
```yaml
settings:
schema: { instance: "init.luau", export: "public" }
```
Whether an instance may lack its schema file is what the type's `files:`
block says of that file. Listed under `files.optional`, it may be absent, and
an instance without it declares no settings — the importer type lists it
there, since most importers take none. Listed under `files.required`, or not
listed at all, it must load, and an instance missing it is a broken
declaration and is logged.
`schema.type` is required at the folder relative to the TYPE's own
`.assetType/` directory (one schema shared by every instance).
`schema.instance` is required relative to each INSTANCE's own folder (`init`
resolves the instance's own identity; anything else is a sibling module under
it). Without `schema.export`, the file is required as a module and its return
value IS the schema. With `schema.export`, the file is run in an environment
of its own and `export` is read from a returned table carrying it, or else
from the globals the file assigned — a component's `public` is such a global.
That environment reads through to `_G` and takes every write itself; its own
`_G` is itself, its `declare` and `computed` record into it, and its `task`
records spawned, deferred and delayed work instead of starting it. Every other
global is the real one, so a call the file makes through one runs as it does
anywhere. The schema is the declared table's Field descriptors. A schema that
resolves to nothing says why through `Settings.schemaProblemOf(ref)`: the file
could not be read, compiled or run, or declared no such table. An instance
schema is read again when its file, its type's `type.yaml`, or the entry file
of any module the asset `require`s changes. `Settings.blockFor(typeName)`
returns the raw block; `Settings.schemaForType(typeName)` and
`Settings.schemaOfInstance(ref)` resolve the two schema shapes respectively;
`Settings.schemaFor(ref)` tries the type-level schema first, falling back to
the instance-level one. `ref` naming an assetType asset itself — e.g.
`asset.resolve("texture", "assetType")`, rather than an instance of it —
reports that type's own declared schema, the same one every instance of it
reports.
## Where do an asset's values live?
`settings.values` names a file living beside the asset's own content —
`Settings.valuesPathOf(ref)` joins it onto the asset's path.
`Settings.valuesOf(ref)` / `Settings.writeValues(ref, values)` read and write
it; this module only names where it is. A type that declares its schema with
no `settings.values` keeps no values in the asset — a component's live on each
entity it is on — so `valuesOf` answers nil for it, `asset.create` refuses a
`settings` table for it, and `asset.setSettings` refuses a write.
`Settings.recordedWrite(path, text)` writes a file the way every values file
is written, and an editor uses it for any other file it writes. It writes the
whole contents, records the write into the open undo operation when one is
open (so undoing it restores what the file held), and raises when the write
does not land.
## In what order are a schema's fields declared?
Every `Field.*` constructor stamps its descriptor with `declaredOrder`, one
more than the last. Luau evaluates a table constructor's entries in the order
they are written, so `Settings.orderedNames(schema)` lists a schema's fields —
and a struct's subfields — in the order the source writes them.
A values file, or a legacy `.metadata` settings block, may hold an older
spelling — a renamed field, an older enum member. Every read passes what is
stored through the type's `normalizeSettings` (`Settings.normalizeFor`), so
it answers in the fields the schema declares today, and writes nothing. The
next local edit of that asset rewrites the file in the declared spelling
(`Settings.healLegacyIfNeeded`).
`asset.setSettings(ref, patch)` writes a partial patch:
`Settings.resolvePatch(ref, patch)` normalises it, merges it over the current
values and applies the type's derived defaults for the fields it changed, and
`Settings.writeValues(ref, values, patch)` applies the corrections, checks the
schema and writes the file.
## How is a new asset's settings resolved at creation?
`asset.create` calls `Settings.resolveForCreate(typeName, name, destPath,
creationOpts, callerSettings, importerSettings)` before running the type's
`onCreate`, checks the result against the schema, writes it to the values
file, and hands `onCreate` a COPY of it as `opts.settings` (`Settings.
cloneValues`) — never the same table the values file gets, so nothing
`onCreate` does to its own copy can reach what was stamped. `onCreate` reads
settings from `opts.settings` and never writes to it. `asset.create` also
seeds the change baseline with the stamped values
(`Settings.seedChangeBaseline`), so the values file's own first dispatch
reports nothing changed and the payload `onCreate` encoded is the only
encode a create runs.
The layers, lowest priority first, each overriding the ones before it field
by field:
1. The schema's own declared defaults (`Settings.defaultsOf`).
2. The type's own `settingsDefaults(name, opts, asked)` hook, when its
`behavior.luau` exports one. `asked` holds what layers 3 to 5 name, so a
default can follow a field one of them sets.
3. The Preset Manager's matching row (`Settings.presetLayerFor`).
4. The creating importer's settings for this type.
5. The `settings` table the caller passed to `asset.create`.
6. The type's own `settingsDerivedDefaults(values, explicit, changed)` hook,
when its `behavior.luau` exports one — a field whose default follows
another field, set only when no layer from 2 to 5 named it.
7. The type's own `settingsCorrections(values, name, opts)` hook, when its
`behavior.luau` exports one — applied last, once every other layer has
merged.
Layers 2 to 5 are each read through the type's `normalizeSettings`, so a
layer naming a field in an older spelling sets the field it names today.
`asset.create`'s top-level settings alias accepts those older names too
(`Settings.acceptedFieldNames`).
Layer 7 is `Settings.applyCorrections(typeName, values, explicit, context)`,
the one corrections path every settings write takes — this create chain, and
`Settings.writeValues` for every later write (`asset.setSettings`, a type's
first-encode seed, the legacy heal). `explicit` names the fields the writer
asked for: the caller's `settings` table here, the patch for
`asset.setSettings`. A correction lands SILENTLY on a field the writer did not
name — nobody asked for that value, so overriding it just states a fact. A
correction that contradicts a field the writer named REFUSES the write,
naming the field, the value asked for, and why it cannot hold — the same as
every other place this codebase refuses an explicit request it cannot satisfy
(a `Field.checkSchema` violation, a BC7 alignment error) rather than silently
rewriting it into something else. So `asset.setSettings(tex, { compression =
"rgba16" })` on a mipped texture stores `generateMipmaps = false` beside it,
while `asset.setSettings(tex, { compression = "rgba16", generateMipmaps = true })`
is refused.
`Field.checkSchema` runs once, over the result AFTER the corrections hook has
applied — a bad value nothing corrects refuses the creation.
### Four hooks, four different jobs
Every hook is an optional export on a type's `behavior.luau`, alongside
`onCreate` / `onChange`. **None is ever handed a table to mutate** — each
reads what it's given and RETURNS a table of what it wants changed (or nil);
`resolveForCreate`, `resolvePatch`, `applyDerivedDefaults` and
`applyCorrections` are the only places that write to the values, by merging
what a hook returns the same way every other layer merges.
- **`normalizeSettings(values) -> values`** maps every older spelling a
stored file or a write may carry to the field and member the schema
declares now, returning a new table; a table naming both an older field
and its replacement keeps the replacement. The companion export
**`normalizedSettingNames = { ... }`** lists the older field names it
accepts beyond the schema, so a write naming one is not refused as an
undeclared field. `texture.assetType`'s maps the fields its earlier schema
stored to `colorSpace` + `compression`, and the older `filter` keywords to
`linear` / `nearest`.
- **`settingsDerivedDefaults(values, explicit, changed) -> partial?`**
answers the values of fields whose default follows another field. At
creation `changed` holds every field; on a write it holds the fields the
write moved. A returned field applies only where `explicit` — the fields
the writer named — does not name it.
- **`settingsDefaults(name, opts, asked) -> partial?`** supplies a DEFAULT
the schema itself has no syntax for — something only knowable at creation
time, like a naming convention, a fact read off a payload the caller handed
in, or a value that follows a field a higher layer sets (`asked` holds what
the Preset Manager, the importer and the caller name, the higher one's
value where two name a field). It runs early (layer 2 above), so any later
layer — Preset Manager, importer, caller — freely overrides it.
`texture.assetType`'s returns the `textureType` the name suggests (a
`_normal`-suffixed name is a `normalMap`), `compression = "uastc"` and
`maxDimension = 4096`, with `rgba8` for a `textureType` of `sprite` that a
higher layer names; for a pre-encoded ZTEX payload it returns the colour
space, compression and sampler the payload's own header carries. Either
way, an explicit `settings = { ... }` from the caller still wins.
- **`settingsCorrections(values, name, opts) -> (partial?, reasons?)`**
enforces a CROSS-FIELD CONSTRAINT the schema itself has no syntax for — a
fact about one field that depends on another field's resolved value, true
regardless of which layer produced that value. It runs last (layer 7
above), over the fully merged `values`, and again on every later write of
the values file. Nothing is left unmet in what gets
validated and stamped — but a value the caller explicitly asked for is
never silently rewritten to satisfy it; `applyCorrections` refuses instead
(see above). The optional second return, `{ [field]: reason }`, supplies
the "why" for that refusal message; a field with no reason falls back to a
generic one. `texture.assetType`'s returns `{ generateMipmaps = false,
maxDimension = 8192, colorSpace = "linear" }` whenever the RESOLVED
`compression` is high-precision (the encoder stores one verbatim, linear,
and refuses a mip chain or a downsample for it outright), paired with a
reason naming the compression, and `nil` otherwise.
## What does a declarer declare?
`Field.settingsOf(identity, mode)` embeds another declarer's schema as a
struct field without restating it. The identity names one of two kinds of
declarer, and `Settings.schemaOfDeclarer(identity)` tells them apart by what
`identity` resolves to:
- **An assetType** (e.g. `"@builtin::assetTypes.texture"`) — embeds the
schema every instance of that type carries, resolved via
`schemaForType`. This is the type-level shared schema from the section
above, not a per-instance one — an assetType has no settings of its own
to declare per instance.
- **Anything else** (an importer, or any other asset that declares settings
of its own) — embeds that asset's own schema, resolved via
`schemaOfInstance`.
Every schema this module serves has already run its `Field.settingsOf`
fields through this resolution — a caller reading `schema.someField.fields`
never sees an unresolved `declarer` with no `fields`. Resolution descends
into an already-literal struct's `fields` and a list's `element` the same
way, so a declarer embedded several fields deep is still reached. A declarer
that embeds itself, directly or through another declarer, stops one level
short of the loop instead of recursing forever.
## What are the defaults?
`Settings.defaultsOf(schema)` reads every field's declared `default` into a
plain table — a field declared without one is absent from the result rather
than holding a `nil` value.
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# edui.inspector.parts
The building blocks a type's `inspector.luau` composes its sections from. Every
Context carries this module as `ctx.parts`, so an inspector file requires
nothing from `@builtin::editor`:
```luau
return { sections = { {
id = "summary", title = "Summary",
build = function(ctx)
local rows = ctx.parts.facts(ctx, {
{ label = "Vertices", value = 24 },
{ label = "Size", value = ctx.parts.bytes(1536) },
})
local n = #rows
for _, node in ipairs(ctx.parts.action(ctx, "rebuild", "Rebuild", function() ctx.ref:rebuild() end)) do
n += 1
rows[n] = node
end
return rows
end,
} } }
```
Every function takes the section's Context first and returns a list of edui
nodes, unless stated.
| Part | What it shows | Callback key |
|---|---|---|
| `format(v)` | a value as text: integers plain, other numbers to 4 significant digits, booleans yes/no, a list as its length, a map as its entry count (returns a string) | — |
| `bytes(n)` | a byte count as text: `84 B`, `1.5 KiB`, `2.00 MiB` (returns a string) | — |
| `facts(ctx, rows, empty?)` | label/value rows (`{ label, value, mono? }`); the value takes the width its label leaves and wraps within it; a row whose value is nil shows "—", so a value that could not be read is seen to be missing. A row that does not apply to the subject is left out of `rows` by the section; with no rows `empty` shows | — |
| `list(ctx, items, { max?, empty?, mono? })` | one text row per item, at most `max` (40), then "… and N more" | — |
| `table(ctx, key, columns, rows, empty?)` | a table of records, each cell through `format` | `<keyPrefix>:tbl:<key>` (widget id) |
| `links(ctx, refs, { max?, empty? })` | one button per asset (an AssetRef, a `{ __ref = guid }` envelope, or a guid or name), named and typed; clicking selects it. An item that does not resolve is listed as text | `<keyPrefix>:link:<guid>` |
| `entityLinks(ctx, ids, { max?, empty? })` | one button per entity, by name; clicking selects it. An id whose entity no longer exists is listed as text, marked despawned | `<keyPrefix>:ent:<id>` |
| `action(ctx, id, label, run, { primary? })` | a button running `run`; a run that raises shows its message beneath the button until the next run | `<keyPrefix>:act:<id>` |
| `openFile(ctx, path, label?)` | an action opening `path` in the Code panel; nothing when the file is absent | `<keyPrefix>:act:open:<path>`, the path relative to the subject's folder |
| `problems(ctx, problems, clean?)` | one notice per `{ message, code?, severity?, line? }` (error tone, or info for a warning, info or hint), or `clean` ("No problems.") | — |
| `swatch(ctx, color, label)` | a colour square (`{ r, g, b }` in 0..1) beside its label and hex (returns one node) | — |
| `cached(key, paths, compute)` | `compute()`'s value, computed again only when the content version of one of `paths` moves (returns the value). Read through `ctx.parts`, it is held while a Context that read it stays open; read through the module itself, until the next `Inspector.release` | — |
| `state(ctx)` | the table a Context's sections keep state in between builds (a picked zoom, a chosen tab), forgotten when the Context is released (returns the table) | — |
| `check(ctx, path)` | a "Check" action running `lsp.check(path)`, then the counts and diagnostics of the last check of the file's current content | `<keyPrefix>:act:check:<path>`, the path relative to the subject's folder |
| `values(ctx, { subject, schema?, values?, write?, readOnly? })` | typed controls over any values: one control per schema field, each edit checked with `Field.check` and written through `write` inside one undoable operation; `readOnly` shows the values with no control that writes. The same subject shown by two Contexts keeps two states | `<keyPrefix>:val:<subject>:set:<field>` |
## Rules a section keeps
- **No write in `build`.** A build only reads; writes happen in an action's
`run`, in `ctx.setSettings`, or in a `values` part's `write`.
- **Expensive reads are once per content version.** A build that decodes a
payload, walks a file or asks the LSP goes through `cached` (keyed on the
files the value comes from) or runs behind an action. `check` holds each
file's last result for as long as the file's content is unchanged.
- **Every callback key starts with `ctx.keyPrefix`**, so two subjects — the
panel's asset and an inline editor of the same asset — never share one.
- **What the parts hold goes with the Context.** `ctx.parts` is the parts as
that Context reads them. `Inspector.release(keyPrefix)` forgets the
Context's action failures, file checks and state, and every cached value no
other open Context read.
▲ 0↑ born
# 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. The body runs in
an environment of the module's own: a name it declares without
`local` is readable by the module's own functions and by no other
script, so an export reaches its callers through the returned table
and nothing else. Requiring a component's folder runs its chunk the
same way, once, and its `update`, `start` and `public` stay in that
environment; a component runs on an entity through
`entity(id).component.add(name)`.
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()`.
A name the body declares without `local` lives in the module's
environment, which every run of the module shares: a function the
previous run left in place reads what the reload assigned. 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**.
▲ 0↑ born
# contactShadows
Runtime control of the scene contact shadows — `.set` / `.get` / `.clear` /
`.active`, with `.lights` reading back the lights this frame's traces aim at
and `.refresh` re-reading the scene's lighting. `set` takes any subset; omitted fields keep their value, and a
`strength` of 0 releases the render pass.
For contact shadows a scene should simply have, author the `ContactShadows`
component instead. The full description of the knobs and the pass is in the
package readme: `guides { path = "systems/contactShadows" }`.
▲ 0↑ born
# debugViz render feature
Draws the batched geometry buffer that `@builtin::modules.debugViz` rebuilds
every edit-mode tick from every registered provider — bounds boxes, camera
frustums, and any further gizmo the debugViz core gains. One Draw pass over
the core-owned vertex/index buffer pair, rasterized as GPU lines through the
shared vertex-colour unlit material (`@builtin::shaders.debugGeometry`). An
empty state (no providers with geometry yet, or the driving `DebugViz`
component not yet awake) enqueues nothing.
▲ 0↑ born
# assetType runtime
The machinery that reads a `<typename>.assetType/behavior.luau` and turns its
declarations into live behaviour.
A `behavior.luau` is a table of declarations — `ref` methods, `modules` shared
code, an `events` schema, a `namePattern`, `refShapes`, and the `onCreate` /
`onRegister` / `onChange` / `onDelete` / `validate` / `settingsDefaults` /
`settingsCorrections` hooks. None of it runs itself. This is the code that
runs it, and it lives here because reading a type's declarations is the
**assetType type's own behaviour** — the same way `material.assetType` owns
what a `.material` does.
## Sub-modules
| Module | Reads | Responsibility |
|---|---|---|
| `ref.module` | `ref`, `modules` | Builds every `AssetRef` envelope, attaches the shared metatable, and dispatches per-type methods and shared modules onto it. Also owns edit-mode write-behind persistence. |
| `create.module` | `onCreate`, `namePattern`, `validate` | Backs `asset.create`: resolves the type, checks the name against its pattern, runs `onCreate` (or clones `template/`), and writes the instance. `validate.module` beside it checks a creation `opts` table against the type's `createSchema`. Before running `onCreate`, resolves the type's settings chain (below) and hands the result to the hook as `opts.settings`. |
| `settings.module` | `settings`, `settingsDefaults`, `settingsCorrections` | A type's declared settings schema and where its values live (`type.yaml`'s `settings:` block). `Settings.resolveForCreate` layers the schema's own defaults, the type's own `settingsDefaults(name, opts, asked)` hook (a DEFAULT the schema can't express — a name-derived convention, a fact read off a payload the caller handed it, a value following a field `asked` shows a higher layer naming; any later layer overrides it), the Preset Manager, an importer's settings, the caller's `settings` table, then the type's own `settingsCorrections(values, name, opts)` hook (a CROSS-FIELD CONSTRAINT the schema can't express, applied last over the fully merged values). A correction over a default/preset/importer value lands silently; a correction that would override what the caller's own `settings` table explicitly asked for refuses the creation instead, naming the field and why. Neither hook is ever handed a table to mutate; each returns what it wants changed (`settingsCorrections` may also return a `{ [field]: reason }` table for that refusal message). `Settings.cloneValues` deep-copies a values table — `create.module` hands `onCreate` a copy, never the table it stamps. `Settings.valuesOf` / `writeValues` read and write an asset's own values file. |
| `typeYaml.module` | `type.yaml` | The folder a type lives in and its parsed `type.yaml`, decoded once per content version of the file. `settings.module` and `inspector.module` read their blocks through it. `about` / `aboutAt` read a type's `about.yaml` (`intent`, `function`, `usage`), leaving out any key that is empty or still starts with `[[describe]]`; `aboutRows` and `aboutMarkdown` lay the texts out for the Inspector and the `types/<name>` guide. |
| `inspector.module` | `type.yaml`'s `inspector:` block | Which inspector a type declares for its assets (`inspector: { type: ... }` or `{ instance: ... }`), and the declaration that file returns — the sections it adds, the generic ones it replaces, and their order — or the problem that kept it from loading. |
| `onRegister.module` | `onRegister` | Fires an instance's once-only registration hook — on arrival, on world load, and for `@builtin` library instances. |
| `changeDispatch.module` | `onChange`, `onDelete`, `refShapes` | Routes a VFS source write or a folder delete to the enclosing typed asset's type hooks. |
| `refShapes.module` | `refShapes`, `ref` | Publishes what every `AssetRef<category>` answers to, so a member read on an asset-typed value is checked against that category's real surface. |
| `events.module` | `events` | The per-asset event runtime behind `ref.events`. |
| `instantiable.module` | `ref.instantiate` | The instantiation contract an asset type opts into: `root` stands the root entity, `place` applies the base placement opts to one the type adopted, and `result` shapes the `(root, idMap)` every `instantiate` returns. Also registers the `sceneInstantiable` field-constraint validator. |
| `declaration.module` | `type.yaml` | The type's decoded declaration, read once and held until a write inside an `.assetType` folder; what every question about a type as a whole reads. |
| `previewRecipe.module` | `type.yaml` `preview:` | How an instance's `preview.png` is produced: which of the four recipes (`instantiate`, `image`, `surface`, `custom`) the type declares, and what that recipe needs. |
## Reaching it
```luau
local rt = require("@builtin::assetTypes.assetType.shared")
rt.ref.loadTypeBehavior("material")
```
Fields resolve lazily. The prelude requires the sub-modules directly, in
dependency order (`ref`, then `changeDispatch`, `onRegister.install()`,
`refShapes.install()`) — a table that required all six on load would take that
ordering away from it.
▲ 0↑ born
backing path · renderFeatures/uiMotion.renderFeature
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