3D Textures and Pixel Shaders

With the introduction of programmable pixel pipelines, graphics features that were once somewhat obscure are now finding additional uses. One example of this is 3D or volumetric textures. While 3D textures have been in high-end graphics hardware for about a decade and appeared in consumer hardware nearly two years ago, few real applications have been created to take advantage of them. The reality is that real-time shading is still largely a discipline of pasting multiple 2D images onto 3D surfaces. Programmable pixel shaders have enabled a variety of unique algorithms, and 3D textures are a concise way to implement techniques that might be awkward or impossible with just 1D or 2D textures. In this chapter, we will define 3D textures and then present a variety of shaders which use them to achieve effects that are either awkward or impossible with 1D or 2D textures.