Support for Morphed `Texcoord_n` and `Color_n` Attributes

Looks like the glTF spec added the optional Texcoord_n, and Color_n morph targets. Should this be supported in IMorphTargetBuilder and IMeshDecoder?

Client implementations SHOULD support at least three attributes — POSITION, NORMAL, and TANGENT — for morphing. Client implementations MAY optionally support morphed TEXCOORD_n and/or COLOR_n attributes. https://www.khronos.org/registry/glTF/specs/2.0/glTF-2.0.html#morph-targets

I have a file format I’m converting to that supports Texcoord_0 and Color_0 morphing, however it’s not an often used feature.

[vpenades]

yes, it’s a useful feature, and I’m surprised it was not part of the spec since the very beginning.

Although I don’t think I’ll be able to work on it for the next release, I’ll add it to the roadmap, though.

[vpenades]

Looks like if the morph target doesn’t have position deltas, then calculating smooth normals fails (line 87). The position deltas is null.

@ptasev I couldn’t replicate that scenario, could you write a test case for it?

I thick after the morph targets and a few other issues are resolved, I’ll publish new nugets