GLTFLoader: Support InstancedMesh / 'EXT_mesh_gpu_instancing'

It would be nice if GLTFLoader automatically created InstancedMeshes from a GLTF file including instanced meshes.

Here is an exemple file : instanced_cube.glb

Blender lets us reuse a mesh ( like other modeling softwares I’m sure ), here is the hierarchy in Blender :

I would like GLTFLoader to (optionaly?) create an InstancedMesh of this cube, instead of making several identical Meshes, because :

• Manually removing the created Meshes to replace them with an InstancedMesh is tedious.
• It takes memory for nothing. ( potentially a lot )

Some context :

A GLTF file can reuse meshes, this is what the GLTFLoader.parse get after reading the file above :

[takahirox]

Sorry for slow progress because I have been a bit too busy…

Recently I have fixed some improtant problems in the plugin which I really wanted to resolve before moving it into GLTFLoader.

There is still lack of some supports, SkinnedMesh and better custom instance attributes handling, but they are advanced features. We may be able to start to consider to move the plugin into GLTFLoader as built-in plugin and can think of advanced feature supports later.

If it sounds good, I want to make a PR hopefully soon.

[takahirox]

Some additional notes…

I already released the EXT_mesh_gpu_instancing glTF loader plugin at

https://github.com/takahirox/three-gltf-extensions/tree/main/loaders/EXT_mesh_gpu_instancing

You can use it now, but note that I didn’t test well yet. Some glTF or Three.js functions might not work (e.g. animation). Once I confirm the functionalities I would think of moving it into the Three.js glTF loader as built-in plugin.

As @donmccurdy explained, our work requires pre-processing. I don’t think of automatically converting the regular meshes to instanced mesh. If you still want to automatically do that, you may write your own plugin with the plugin API (Three.js glTF loader extensibility mechanism). We haven’t written the plugin API document yet, so please refer to the plugins in

https://github.com/takahirox/three-gltf-extensions/tree/main/loaders/

and the built-in plugins in the glTF loader for the API.