Computing inverse of model view matrix

[chipheo]

Hello everyone,

Is there anyway we can get the inverse matrix of the model view matrix in OpenGL efficiently? Of course, we could get that matrix by glGetDoublev(GL_MODELVIEW_MATRIX,m) and then compute the inverse of m manually, but it's way too long since internally, I think, OpenGL must use the inverse to transform normal vectors.

Any help would be greatly appreciated.

Chip

[DFrey]

That is the only way to do it generally. However, if you happen to know that the model view matrix is only a concatenation of rotation matrices, then computing the inverse is trivial, its just the transposition.