I have a small problem with vectors, I''m sure the solution is rather easy, but I just can''t find it
OK, I have a 3D point P(x,y,z). I rotate this point around the origin of the coordinate system using an arbitrary (but valid) 3x3x3 rotation matrix M: Pn = P * M
Now, I have an arbitrary unit vector A (independent of the point or matrix) going through the origin. I would like to know, how far the transformed point Pn has rotated around A (seen as an axis).
Currently I''m doing this by projecting P and Pn onto the plane formed by A (A beeing it''s normal) and measuring the angle between the two projected points with respect to the origin. This works but seems a bit kludgy, isn''t there some way to directly extract this information from the matrix and A, without having to project the points ?
A.H aka Blueshift