These beautiful napkins are drawn by a very simple formula:
x = y - sign (x) * sqrt ( abs ( B * x - C ))
y = A - х
View them being drawing here (press the spacebar there to regenerate with the new random constants a, b and c). Download the source here ([URL=“http://granik.com/flashexp/napkin_bmp.fla”]Flash 8). View some interesting iterations [URL=“http://antongranik.livejournal.com/15502.html”]here (LJ).