Are the dots moving in a circle? The shapes? Alter radius, speed. Spacebar changes dot color. On the right, dots move in a straight line, yet the shapes are circling. How? Spacebar changes color of dots.
Related to the "Tusi couple" illusion, but I made these into shapes! Moving dots are moving along hypocycloids (a special kind of hypotrochoid). Right: shapes circle but dots move in straight lines. Left: total radius is wider. You get curves instead of straight lines, a hypocycloid with a typical spirograph pattern. From my earlier: https://scratch.mit.edu/projects/1037717092/ Code sets phase change to equal angle change.
