Practical Algorithms for 3D Computer Graphics, 2nd Edition

498 11. Algorithms for procedural textures

displacement and transparen cy mapping. An example of a furry texture can be

seen in figure 11.36 where the edge silhouette has become streaked and blurred

and the normal view gives a depth perception that is only really discernible in a

stereoscopic rendering.

The combination of surface displacement and transparency mapping is gen-

erally referred to as the Shells algorithm because the idea is to build a series of

surface layers, shells, around the object by moving the vertices a small distance

along the direction of the normal vector at each vertex. Typically 10 to 20 shells

may be needed and each one is