iPhone 3D Programming

Chapter 8. Advanced Lighting and Texturing

There are two kinds of light—the glow that illumines and the glare that obscures.

—James Thurber

At this point in this book, you may have written a couple simple OpenGL demos to impress your co-workers and family members. But, your app may need that extra little something to stand out from the crowd. This chapter goes over a small selection of more advanced techniques that can give your app an extra oomph.

The selection of effects dealt with in this chapter is by no means comprehensive. I encourage you to check out other graphics books, blogs, and academic papers to learn additional ways of dazzling your users. For example, this book does not cover rendering shadows; there are too many techniques for rendering shadows (or crude approximations thereof), so I can’t cover them while keeping this book concise. But, there’s plenty of information out there, and now that you know the fundamentals, it won’t be difficult to digest it.

This chapter starts off by detailing some of the more obscure texturing functionality in OpenGL ES 1.1. In a way, some of these features—specifically texture combiners, which allow textures to be combined in a variety of ways—are powerful enough to serve as a substitute for very simple fragment shaders.

The chapter goes on to cover normal maps and DOT3 lighting, useful for increasing the amount of perceived detail in your 3D models. (DOT3 simply refers to a three-component dot product; despite appearances, it’s not an acronym.) ...