As you can see, both the outer shadow and the inner shadow are visible, as well as the transition from outer to inner. I was actually surprised to find out that the inner shadow is a simple diamond! This would mean that the radius of the inscribed circle actually changes linearly with the height of the cube. I hadn't realized this.
I guess what is nice about the program is that it can be used to rotate any type of 3-d object, not just a cube. One could also rotate a pyramid, a torus, or any other shape that can be simply defined.
The main point of his article was that we can't take the dimensionality of an activity or a movement for granted. He seemed to suggest that there is a difference between "degrees of freedom" and "dimension." Thus while human beings exist in what we think of as a three dimensional world, we are (primarily) limited to the surface of this world. While our space is three dimensional, our degrees of freedom are two dimensional. The difference between the two can perhaps best be demonstrated by one of the latest first-person perspective 3-D video games: Descent. Unlike its predecessors, Descent allows the player six degrees of freedom. The system of tunnels which the player explores contains not only "left, right, forward, and back," but also "up" and "down." This of course leads to a startling disorientation (and sometimes even nausea), since the player is not used to thinking in six degrees of freedom. Just as four dimensional objects are not easily grasped by human intuition, neither are worlds with six degrees of freedom. If only we lived in a world like Descent . . .