This demo shows a stereo projection from a rectangluar torus (1/sqrt(2))*(a*cos(u),a*sin(u),b*cos(v),b*sin(v)) sitting on the unit 3-sphere to 3-space. The projection is given by (x,y,z,w) to (x,y,z)*(1/(1-w)). In a separate window it shows the same projection after the torus has been rotated in 4-space.