   GPG4: Hardware Skinning with Quaternions/ spherical joint blending
  Hi,I read the Game Programming Gems 4 article "Hardware Skinning with quaternions" but it is a bit short in it's explaination of the technique. Unfortunately I don't find any information about it in google except that there is an article about it in GPG4. Would be great if someone here could give me a hint what to search for.Unfortunately there is no online version so I try to give a summary of what the article describes (as far as I understood):Instead of blending final vertex positions it tries to interpolate transforms that give a skinned vertex. The vertex is bound to one bone but (somehow) the rotations of several bones are spherecally interpolated as quaternions in the vertex shader. Any help appreciated.Thanks,Markus   