ColladaLoader: Use Object3D.animations.

[Mugen87]

Related issue: #20738

Description

Since Object3D.animations is now available, I suggest to migrate all loaders to use the new property (FBXLoader already uses this approach). In this way, no separate property in the result object is necessary anymore. Besides, the editor (and potentially other software) can lookup animation clips at a common place.

The change in ColladaLoader is backwards compatible by introducing a getter for the old animations property. This could be removed after a few releases.

If the PR gets merged, I'll change the remaining loaders in the same fashion.

[mrdoob]

Thanks!

[Mugen87]

@donmccurdy glTF supports multiple scenes but after some research I've found KhronosGroup/glTF#1542.

Do you think it's safe to assign the animation clips to gltf.scene.animation? Or should we assign an animation to each scene where it animates a node?

[donmccurdy]

KhronosGroup/glTF#1542 is really a proposal for glTF 3.0, which is probably still a long way off. I wouldn't read into that at this point. I'd suggest either:

a. return only the current gltf.animations list
b. attach scene.animations containing only animations that affect the given scene, for all scenes in the file

[Mugen87]

Okay, then I think I will give b) a try.