PropertyBinding: Allow map as target object.

[Mugen87]

Related issue: -

Description

It should be possible to animate the texture properties offset or rotation like in this fiddle: https://jsfiddle.net/37mfsugc/2/

However, since map is no part of the supported object names in PropertyBinding, it does not work if the animation is played in context of a 3D object.

The workaround would be to change the root object of the animation mixer to the texture which is problematic since animations are usually registered for 3D objects.

This PR has no effect on existing animations.

[donmccurdy]

In the JSFiddle the keyframe track name is material.map.offset, though looking at the code here I think I would have expected it to be something more like map.offset or .map.offset, is that intended? All else being equal I think <node-name>.material.map.offset would be ideal, but I understand that's one level deeper than we currently parse and might present a problem.

+1 for supporting textures as property binding targets here, thanks!

/cc @hybridherbst relevant to #24108

[Mugen87]

In the JSFiddle the keyframe track name is material.map.offset, though looking at the code here I think I would have expected it to be something more like map.offset or .map.offset, is that intended?

Yes, the keyframe track name has to start relative from the 3D object.

[mrdoob]

Thanks!

[arpu]

@Mugen87 would be nice to have this for normalMap too?

[Mugen87]

I'm trying to think of a solution that scales well for more map types.

[hybridherbst]

@Mugen87 in case you want to take a look at all that would be needed for KHR_animation_pointer (effectively allowing all glTF properties to be animated), here's what I had to change for that:
https://github.com/mrdoob/three.js/pull/24108/files#diff-868e3d9b3219d163d7d53939fc3f7a6e65b7664ad5e3da03cd31fa23ea1a6df6R829-R917

(not saying that's a great implementation, but it covers all required cases as far as I'm aware)