threejs

name: threejs description: Three.js scene-graph parsing and export workflows: mesh baking, InstancedMesh expansion, part partitioning, per-link OBJ export, and URDF articulation.

Three.js Scene Graph + Export

Quick start

1. Load the module, call createScene(), then updateMatrixWorld(true).
2. Treat named THREE.Group nodes as parts/links.
3. Assign each mesh to its nearest named ancestor.
4. Bake world transforms into geometry before export.
5. Export per-part OBJ (and optionally URDF) using deterministic ordering.

Scene graph essentials

Object3D (root)
├── Group (part)
│   ├── Mesh
│   └── Group (child part)
│       └── Mesh
└── Group (another part)
    └── Mesh

• THREE.Scene / THREE.Object3D: containers
• THREE.Group: logical part (no geometry)
• THREE.Mesh: geometry + material

Part partitioning rules

• Parts are named groups at any depth.
• Each mesh belongs to the nearest named ancestor.
• Nested named groups are separate parts; do not merge their meshes into parents.
• Skip empty parts; sort part names for determinism.

function buildPartMap(root) {
  const parts = new Map();