Inspired by a drawing by @regolo54 (sooo much more elegant than this). This applet rotates a quadrilateral around a point and then draws shapes among the intersections. Pretty fun to play with; on GeoGebraTube.

The option checkbox does polytopes on all the intersections, and the more checkbox sometimes adds a few more.

There’s a tool for making or adding your own. Select the center, then enter how many (N for the slider) and then three vertices for a triangle.


Zuzu’s Petals.

I saw a neat image at the dailyminimal tumblr, (greyscale image above)
that got me playing around with these petals. I decided to make the arcs circular, with a control C to move the center, and B to control the angle of the arc. To get the fading effect I included a second slider to do the in between rotations, repeating to get more opaque.

It’s at GeoGebraTube if you want to make your own.