This recipe will demonstrate a performance efficient technique, which makes use of the procedural texture to produce the illusion of a real 3D object. In the Gouraud shading, fragments are painted with light shadings based on the direction of the light source and the geometry shape. For instance, in Chapter 5, Light and Materials, we implemented the diffuse light on a spherical model, which contains a very high number of vertices. This recipe technique renders the same diffused sphere, but using only four vertices. It fakes the light shading in such a way that the difference between the two becomes indistinguishable.

The performance is directly proportional to the number of fragments it renders to the screen. For example, the surface area covered by a single fullscreen rendering sphere is equivalent to several tiny spheres covering up the same surface area on the screen.