Chapter 7. Primitive Assembly and Rasterization

In this chapter, we describe the types of primitives and geometric objects that are supported by OpenGL ES, and how to draw them. We then describe the primitive assembly stage, which occurs after the vertices of a primitive are processed by the vertex shader. In the primitive assembly state, clipping, perspective divide, and viewport transformation operations are performed. These operations are discussed in detail. We then conclude with a description of the rasterization stage. Rasterization is the process that converts primitives into a set of two-dimensional fragments, which are processed by the fragment shader. These two-dimensional fragments represent pixels that may be drawn on the screen.

Refer to Chapter 8, “Vertex Shaders,” for a detailed description of vertex shaders. Chapter 9, “Texturing,” and Chapter 10, “Fragment Shaders,” describe processing that is applied to fragments generated by the rasterization stage.