Playing elliptic billiard generates rotational discrete constant mean
curvature surfaces. The generated billiard curve is unrolled and the trace
of one focus defines another discrete curve. Rotating this curve around the
x-axis generates a discrete CMC surface.
Pick a point inside the ellipse the select an initial point. Look at the
unrolled curve or the surface by selecting one of these checkboxes. The
trace of the focus is the red polygon, the billiard curve is colored blue.