I thought of a quite small addition to OpenGL that might make it a little easier on us programmers…What if when specifying vertices we could specify TWO NORMALS instead of one .
The second normal could be user defined (a la binormal or tangent normal, or another vector entirely). This would help in vertex programs, would it not? Bone meshes could rotate the main normal around the extra normal, all in hardware (search for SLERP). Bump-map algs could use the extra normal too. I see many uses and it is only one extra thing to add (4 floats/doubles). So, what you think