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yawn/docs/guide/meshes-and-instances.md
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Provide the single-loadout Scene API, SAB-backed meshes, cameras, materials, lights, workers, post effects, and tutorial playgrounds. Batch matching row growth so active GPU loadouts refresh once.

Amp-Thread-ID: https://ampcode.com/threads/T-01a01380-b478-77d0-84a0-102880a5c5ae
Co-authored-by: Heaust Azure <heaust.azure@gmail.com>
2026-08-20 06:39:30 +00:00

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# Meshes and instances
Every `Mesh` is an instance. `clone()` shares geometry and allocates only a new node/mesh slot.
```ts
const source = new Mesh(scene, {
vertexData: {
positions: [-0.2, -0.2, 0, 0.2, -0.2, 0, 0, 0.25, 0],
indices: [0, 1, 2],
},
});
await source.ready;
for (let x = -4; x <= 4; x++) {
const instance = source.clone({ position: [x * 0.2, 0, 0] });
await instance.ready;
}
```
<Playground example="instances" />
## Copy-on-write geometry
The default vertex kinds are `positions`, `normals`, `tangents`, `uvs`, `colors`, and `indices`. Mutating any kind on an instanced clone first makes that mesh's geometry unique.
```ts
const clone = source.clone();
await clone.ready;
await clone.setVertexData("positions", [
-0.4, -0.2, 0,
0.4, -0.2, 0,
0.0, 0.5, 0,
]);
```
## Per-face materials and visibility
```ts
await mesh.setMaterialForFaces(red, [0, 2, 4]);
mesh.material = blue;
mesh.isVisible = false; // one direct u32 write
```
Face rows store optional material pointers; a zero lane falls back to `mesh.material`.
<script setup>
import Playground from "../.vitepress/Playground.vue";
</script>