Chapter 5 - Texture mapping

Abstract

This chapter reviews OpenGL's texture mapping abilities with an emphasis on features important to more complex rendering techniques. Texture mapping is a fundamental method for controlling the appearance of rendered objects. A common use of texturing is to provide surface detail to geometry by modifying the surface color on a per-pixel basis. A digital image is used as a source of surface color information. Texture mapping can do much more than this. It is a powerful and general technique for combining images and geometry. At the heart of a texture map are the map images, each an n-dimensional array of color values. The individual elements of the array are called texels. The texture image array has one, two, or three dimensions. Core OpenGL requires that the texture image has a power of two dimensions. The main reason for this is to simplify the computations that are required to map texture coordinates to addresses of individual texels. Texture images are created by storing bitmaps into a texture. Texture coordinates associate positions on the texture images to the textured primitive's vertices. In OpenGL, a vertex of any primitive can have texture coordinates associated with it.