Process multiple scenes without merging them

[Inviz]

I really love gltfpack. The speed and quality of code is superb. But I wish there was a bit more control over certain aspects of it. One of them is ability to process multiple scenes. Right now gltfpack outputs a single scene. So i have to use gltf-transform to preprocess file to turn scenes into root nodes.

Another semi-related thing would be super lovely to support multiple input files and glue them together as different scenes. Right now i also do that with gltf-transform, but it all takes a lot of plumbing and hacks

[zeux]

I could add support for multiple scenes; my understanding previously has been that this is poorly supported, some discussion in KhronosGroup/glTF#1542 and other issues on glTF repository. Having said that, I don't think it's going to be too difficult to support, although I don't know if I will be able to find good examples to test against.

Merging multiple input files is challenging though due to how some parts of gltfpack are implemented - parts of the pipeline today use the raw data from the source glTF file (via cgltf library) so the ability to process that is limited...

[zeux]

If you have an example of a model with multiple scenes that'd be great, since glTF-Sample-Models which I usually use for testing doesn't have one.

[Inviz]

Basically, blender exports multiple scenes in a very meaningful way. It's like separate "root" nodes. When there're multiple scenes, one of them is "main" (accessible as like gltf.scene), it is usually the ones that blender was in while exporting. I am not super sure if there's duplication in that case (i.e. if gltf.scene is accessible as gltf.scenes[n] or is it something that GLTFLoader does).

[Inviz]

Let me make you one

[zeux]

"scene" is just a reference to one of the scenes, there should be no duplication in glTF file

[Inviz]

Multi-Scenes.zip

Here's glb, gltf and blender files.

Yes, that's right. Scene is just numeric index. Just checked it myself.

[Inviz]

With multi-scene setup there could be some really interesting things done. E.g. prefabs, merged files, different animation scenes, etc. Blender has very interesting (yet a bit buggy) support for creating different scenes from the same source files, that's what I use.

[Inviz]

Wonderful work! Works well!

[Inviz]

Just wanted to note again, that you are very prolific and your utility is top-class. Does what's advertised on the tin, and is extremely fast at that. On behalf of myself and others, thank you!