Animated 3D projection of a 4D rotation of the 600 cell. While it may look like a simple 3D rotation, that is an illusion - it uses a 4D rotation matrix. There are 3 sets of 45 frames each. Each set rotates through 2Pi on the XW plane. The second set adds (using a dot product on each rotation matrix of the first) a rotation through Pi on the YW hyperplane. The third set adds to the second a rotation through Pi/2 in the ZW hyperplane.