There are two different versions of the OpenGL ES graphics library on your iOS devices. This book has largely dealt with the higher-level one, known as OpenGL ES 1, sometimes referred to as 1.1 or 1.x. The second version is a rather confusingly named OpenGL ES 2. The first one is by far the easier of the two; it comes with all sorts of helper libraries doing much of the 3D mathematics and all of the lighting, coloring, and shading on your behalf. ES 2 eschews all of those niceties and is sometimes referred to as the “programmable function” version (vs. ES 1’s “fixed function” design, which is generally sneered at by the true pixel-jockeys who prefer more control over their imagery, usually for immersive 3D game environments where every little visual footnote is emphasized). For that, OpenGL ES 2 was released.
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