A simple illusion
The first image represents a square which gives the impression that it is moving in three dimensions, though it isn’t. Its motion is a combination of two different kinds of motion in two dimensions. The first kind is a simple rotation around its center, whereas the second is a gradual change in width. The combination of these, plus a slight change in color gives the impression that the square is moving in a three-dimensional space. 🙂
This is one of my first attempts in programming with Processing. See code