Physically Based Rendering, 2nd Edition

Chapter Nine Materials

The low-level BRDFs and BTDFs introduced in the previous chapter address only part of the problem of describing how a surface scatters light. Although they describe how light is scattered at a particular point on a surface, the renderer needs to determine which BRDFs and BTDFs to use at that point and how to set their parameters. In this chapter, we describe a procedural shading mechanism that determines the BRDFs and BTDFs to use at points on surfaces.

The basic idea is that a surface shader is bound to each primitive in the scene. The surface shader is represented by an instance of the Material interface class, which has a method that takes a point to be shaded and returns a BSDF object. The BSDF class holds a set of ...