The window "Domain" displays a domain, a point (u0, v0) in the domain, a subset of the domain colored white, red, blue, and magenta, and a point on the boundary of this subset.

The window "Torus" shows the surface X(u, v) (which by default is the torus X(u, v) = ((2 + cos(v))cos(u), (2 + cos(v))sin(u), sin(v))), the images of (u0, v0), and the colored subset of the domain on this surface (with each point in the domain mapped to a point of the same color).

The window "Normal Image" shows the surface produced by mapping each point on the surface X(u,v) to its unit normal vector, preserving the coloring from the "Torus" window.

It is possible to change the point (u0, v0) and the colored subset of the domain by clicking and dragging the points shown in the "Domain" window, and it is possible to change X(u, v) in the control window.