I'm confused with how Assimp deals with the Bind Shape Matrices (not to be confused with bind transforms for bones/joints) for COLLADA models.
Normally this bind shape matrix is baked into the vertices, either before or during the skinning calculations. But for some reason Assimp bakes it into the inverse binds.
In the ColladaLoader.cpp:
// apply bind shape matrix to offset matrix
aiMatrix4x4 bindShapeMatrix;
bindShapeMatrix.a1 = pSrcController->mBindShapeMatrix[0];
bindShapeMatrix.a2 = pSrcController->mBindShapeMatrix[1];
bindShapeMatrix.a3 = pSrcController->mBindShapeMatrix[2];
bindShapeMatrix.a4 = pSrcController->mBindShapeMatrix[3];
bindShapeMatrix.b1 = pSrcController->mBindShapeMatrix[4];
bindShapeMatrix.b2 = pSrcController->mBindShapeMatrix[5];
bindShapeMatrix.b3 = pSrcController->mBindShapeMatrix[6];
bindShapeMatrix.b4 = pSrcController->mBindShapeMatrix[7];
bindShapeMatrix.c1 = pSrcController->mBindShapeMatrix[8];
bindShapeMatrix.c2 = pSrcController->mBindShapeMatrix[9];
bindShapeMatrix.c3 = pSrcController->mBindShapeMatrix[10];
bindShapeMatrix.c4 = pSrcController->mBindShapeMatrix[11];
bindShapeMatrix.d1 = pSrcController->mBindShapeMatrix[12];
bindShapeMatrix.d2 = pSrcController->mBindShapeMatrix[13];
bindShapeMatrix.d3 = pSrcController->mBindShapeMatrix[14];
bindShapeMatrix.d4 = pSrcController->mBindShapeMatrix[15];
bone->mOffsetMatrix *= bindShapeMatrix;
Is there a specific reason for this? Because this results in a unique set of inverse binds for EACH MESH. So each set of inverse binds is stored with their respective mesh, instead of a global set with the skeleton.
I cannot for the life of me understand why Assimp does this. Why not bake them with the vertices instead, or simply store them somewhere.