This adds blend shape / morph target functionality.
At the FBX level, a mesh can have a number of deformers associated with it. One such deformer type is the blend shape. A blend shape is a collection of channels, which do all the work. A channel can consist of a single target shape (the simple case) or multiple (a progressive morph). In the latter case, the artist has created in-between shapes, the assumption being that linear interpolation between a beginning shape and an end shape would be too crude. Each such target shape contains a complete set of new positions for each vertex of the deformed base mesh.
(It's also supposed to be optionally a complete set of normals and tangents, but I've yet to see that work right; they always come through as zeroes. This is something to investigate in the future.)
So the number of glTF morph targets in a mesh is the total number of FBX target shapes associated with channels associated with blend shape deformers associated with that mesh! Yikes.
The per-vertex data of each such target shape is added to a vector in RawVertex. A side effect of this is that vertices that participate in blend shapes must be made unique to the mesh in question, as opposed to general vertices which are shared across multiple surfaces.
Blend Shape based animations become identical glTF morph target animations..
Fixes#17.
Pär Winzell
Par Winzell