Texture mapping and proceduralism are the two major texturing techniques used in computer graphics. Procedural textures use code to generate colors, instead of extracting them from images. Procedural textures were invented independently by Darwyn Peachey and Ken Perlin in 1985 and have since become an indispensable tool for image synthesis. In general, 3D procedural textures can be applied to non-generic objects, for example, arbitrary spheres and axis-aligned boxes. The basic idea is to fill world space with axis-aligned cubes of two different colors, with the cubes in face contact and the colors alternating across the faces. A. A. Apodaca and L. Gritz also discusses procedural textures. P. Shirley and R. K. Morley and Shirley et al. discuss a stripe texture that renders stripes of alternating colors, instead of checkers. M. Pharr and G. Humpheys discusses 2D and 3D checker textures.