3D asset production pipeline

Tools on this machine

• Blender 5.2 LTS (/opt/homebrew/bin/blender, Homebrew cask) — headless scripting: blender -b file.blend --python script.py.
• @gltf-transform/cli and gltfpack — project dev dependencies in the immersive-3d and experimental templates (npm run assets:optimize). Not installed globally on purpose.
• KTX-Software (ktx/toktx) — not installed (no Homebrew formula; official macOS installer is an admin .pkg). Install manually from github.com/KhronosGroup/KTX-Software/releases if KTX2 is needed; gltf-transform's uastc/ etc1s commands require it. Meanwhile use WebP textures (gltf-transform webp) which need no extra binary.

Pipeline

1. Model for the camera: polycount where silhouettes need it, flat where they don't; real-world scale (1 unit = 1 m), +Y up, applied transforms, clean normals, UVs without overlap where baking.
2. Lookdev in Blender with the same environment intent as the web scene; keep materials glTF-compatible (Principled BSDF → glTF PBR: base colour, metallic/roughness, normal, emission, transmission, clearcoat, sheen, iridescence extensions).
3. Bake what is static (AO, lightmaps, complex shading) into textures; pack ORM (occlusion/roughness/metallic) in one texture.
4. Export glTF 2.0 (.glb): +Y up, selected objects, apply modifiers, include only needed attributes.
5. Optimise:

   npx gltf-transform inspect in.glb                      # report sizes, draw calls
   npx gltf-transform optimize in.glb out.glb \
     --compress meshopt --texture-compress webp --texture-size 2048   # dedup, prune, weld, simplify, instance, compress
   npx gltfpack -i in.glb -o out.glb -cc -tc              # alternative: meshopt + (KTX2 if toktx present)

6. Load with GLTFLoader + MeshoptDecoder (or DRACOLoader) + KTX2Loader (if KTX2). Lazy-load per section.

Budgets (starting point; agree per project)

Verification

gltf-transform inspect before/after table in the PR; the model renders identically (screenshot diff at fixed camera) after optimisation; network panel shows sizes; load time measured from archive/throttled profile.

Failure criteria

Shipping the raw Blender export; 4K textures on phones; unapplied scale (objects 100× size); duplicated materials per mesh; uncompressed geometry > 1 MB; assets loaded before first paint that aren't needed for it.