Flag to start motion. Stop to stop motion. Space to toggle line drawing. s to toggle size changes. Down arrow to reset. Right arrow to advance one step when motion is stopped. Left arrow to advance one step when motion is stopped. Adjust number of Circles slider and click the flag or down arrow. Press the mouse button down on a circle to make it disappear. Move the mouse to where a circle should be to make it appear.
Inspired by Crazy Circle Illusion https://www.youtube.com/watch?v=pNe6fsaCVtI
