Animations for bones with non-uniform-scale rest pose have artifacts

[lyuma]

Godot version:
4.0.dev 45d3b96

OS/device including version:
Windows 10.0.19041.985

Issue description:
Animations have visual artifacts when rotating non-uniformly scaled bones

Here is the animation within Godot:

The artifacts are the result of a desperate attempt to counteract the non-uniform scale: it requires stretching hundreds of units locally just to move a little bit.

Same animation when played in https://gltf-viewer.donmccurdy.com/

One possible fix is to deconstruct the non-uniform-scale component and perhaps multiply it into the child nodes. However, this could affect the hierarchy of existing glTF files so could be compatibility breaking for 3.x

Steps to reproduce:

1. Load the attached project.
2. It should play the animation automatically. if not, enable editable children on the GLB file and play the animation.

Minimal reproduction project:
gltf_non_uniform_bone_animation.zip

[fire]

Deconstruct the non-uniform-scale component and multiply it into the child nodes.

https://github.com/iimachines/Maya2glTF/blob/master/LICENSE

https://github.com/iimachines/Maya2glTF/blob/3d7ba8eaf03ea15afe0720129db88deba7f8749a/src/PolarDecomposition.c#L621-L637

From lox

<Lox> Polar decomposition turns a 3x3 real matrix M into M = R * S with R being a rotation matrix and S being a scale matrix (not necessary uniform or diagonal, i.e. the scale axes can be different to XYZ). This decomposition is unique.

Equivalent you can always turn a 3x3 matrix M into M = R1 * D * R2 with R1,R2 being rotation matrices and D being a diagonal matrix (i.e. S part in TRS). This decomposition isn't unique.

[TechnoPorg]

On current master, the animation looks the same for me as it does in the online glTF viewer. This was probably fixed by #53765, which improved support for non-uniform scaling,

[lyuma]

Thanks for testing and confirming this is fixed!