GLTFLoader: availability of original node info of parsed Object3D (feature request)

glTF handles nodes with their indices (nodeIndex or nodeId in GLTFParser). So some extension data in glTF-based file formats (e.g. bone mapping in VRM) depend on node indices.

However, it seems that objects loaded by current GLTFLoader don’t have any indices info. We can get complete node data from data.parser.json.nodes, but cannot link them with parsed objects in data.scene one to one.

I suggest adding original node info to Object3D.userData or adding an array of nodes with Object3D references to somewhere.

[reminjp]

Now, #15418 seems to be helpfull for me! I love three.js and its contributors.

[donmccurdy]

I should point out that glTF nodes do not necessarily map 1:1 with three.js nodes — in this example…

• node
  • mesh
    • primitive
• node
  • mesh2
    • primitive1
    • primitive2
    • primitive3
    • …

… we attempt to flatten things as much as possible. The first node will result in a single THREE.Mesh, where the second may become a Group containing one or more meshes, or a single mesh, depending on whether the primitives can be merged safely. So unfortunately, even with userData, the mapping you suggest is not trivial.

Do you mind saying a bit more about how you would want to use these indices? If you ensure your objects have unique names, using node names and scene.getObjectByName(...) may be more robust. Or accessing parser.getDependency( 'node', index ) directly, combined with https://github.com/mrdoob/three.js/pull/14492, may be an option.