OpenGL ES is the standard for accessing the hardware accelerated 3D graphics capabilities of modern embedded systems such as the iPhone and iPad. The process of converting geometric data supplied by programs into an image on the screen is called rendering. Buffers controlled by the GPU are the key to efficient rendering. Buffers containing geometric data define the points, line segments, and triangles to be rendered. The OpenGL ES 3D default coordinate system, vertices, and vectors provide the mathematic basis for specifying geometric data. Rendering results are always stored in a frame buffer. Two special frame buffers, the front frame buffer and back frame buffer, control the final colors of pixels on the display. The OpenGL ES context stores OpenGL ES state information including identification of buffers to supply data for rendering and buffers to receive the results.
Chapter 2, “Making the Hardware Work for You,” introduces a simple program to draw 3D graphics with an iPhone, iPod Touch, or iPad using Apple’s Xcode development tools and Cocoa Touch object-oriented frameworks. Examples in Chapter 2 form the basis for subsequent examples in this book.