Physically Based Rendering, 3rd Edition

10.5: Solid and procedural texturing

Once one starts to think of the (s, t) texture coordinates used by 2D texture functions as quantities that can be computed by arbitrary functions and not just from the parametric coordinates of the surface, it is natural to generalize texture functions to be defined over 3D domains (often called solid textures) rather than just 2D (s, t). One reason solid textures are particularly convenient is that all objects have a natural 3D texture mapping—object space position. This is a substantial advantage for texturing objects that don’t have a natural 2D parameterization (e.g., triangle meshes and implicit surfaces) and for objects that have a distorted parameterization (e.g., near the poles of a sphere). In preparation ...