This demo shows the color graph of a function f(x,y,z) over the domain -1 ≤ x, y, z ≤ 1. Each point p = (x,y,z) in the domain is assigned a color according to the value of f(p).
Use the hotspot on the top face of the cube to change the height of the top face. Moving the hotspot around, you can get a look at the the color distribution inside the cube.