It is often possible to represent the apparent discontinuities or transitions of the material properties as changes in the surface structure and vertex properties. This might even be an efficient modeling approach in the case of plain and welldefined patterns, as is the case in Figure 14.1(a). In this particular example, a planar polygon is split at the boundaries of an A-shaped embedded pattern of a different color than the rest of the surface (Figure 14.1(b). But what if the
desired pattern is more irregular and complex, as is the case of the material of the surface in Figure 14.1(c)? Clearly we need a different approach to modify the local material behavior across a polygonal or otherwise-defined surface.