3 Geometry and Transformations

Almost all nontrivial graphics programs are built on a foundation of geometric classes that represent mathematical constructs like points, vectors, and rays. Because these classes are ubiquitous throughout the system, good abstractions and efficient implementations are critical. This chapter presents the interface to and implementation of pbrt’s geometric foundation. Note that these are not the classes that represent the actual scene geometry (triangles, spheres, etc.); those classes are the topic of Chapter 6.