left / right arrow = step K by 1 K key = animate K up / down arrow = step N by 1 N key = animate N https://turbowarp.org/930756564?hqpen
The circle has N points spaced evenly around it, numbered P=1, ..., N. [*] For each point P we draw a line to K*P (mod N). When K=2 this outlines a cardioid, for example. Math puzzle: why does this give families of parallel lines, such as for (K=159, N=512)? [*] Yes, numbered from 1 rather than from 0, which results in the symmetry axis being visibly off-vertical for smaller N. Maybe I'll fix that.
