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yawn/docs/guide/importing-and-picking.md
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Ampandheaust ded70a3cb4 Add interactive tutorial playgrounds
Embed editable split-view examples throughout the guide, restore the full LFS-backed Sponza demo, batch glTF hydration, honor hierarchical transforms, and report transformed BVH picks with a live FPS counter.

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 09:21:21 +00:00

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Markdown

# glTF import and picking
## Import off-thread
The shared importer worker fetches and parses glTF/GLB, then the response hydrates `Mesh` and `PBRMaterial` handles attached to your scene.
```ts
import { importGltf } from "@yawn/handles";
const meshes = await importGltf(scene, "/models/sponza.glb");
meshes[0].position[1] = 0.5;
```
The importer handles triangle primitives, external/data buffers, standard vertex attributes, indices, node transforms, and metallic-roughness values. Application-specific extensions remain application policy.
## Pick in the BVH worker
```ts
const picking = new Picking(scene);
await picking.ready;
canvas.addEventListener("click", async () => {
const hits = await picking.pick([0, 0, 4], [0, 0, -1]);
const nearest = hits[0];
if (nearest) console.log(nearest.id, nearest.distance);
});
```
The worker reads shared node positions and mesh bounds, updates its BVH when the shared frame counter changes, and returns **all** AABB hits sorted by distance. You can shortlist or run an exact test afterward.
If row allocations relocated since `Picking` was created, refresh its shared descriptors:
```ts
await picking.refresh();
```
The playground below imports the repository's full LFS-backed `sponza.glb` in the importer worker, hydrates all 138 primitives, frames them with an arc camera, and sends a real ray to the BVH worker. Click the preview to pick again.
<Playground example="importing" />
<script setup>
import Playground from "../.vitepress/Playground.vue";
</script>