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11 Vertex shaders
In the past chapters, we have been studying the big picture of graphics programming with WebGL: how to create GLSL programs and shaders (Chapter 8), how to draw primitives (Chapter 9), and the syntax and features of the GLSL programming languages (Chapter 10). The programs we have been studying so far cannot do all that muct. The most they can do is drawing simple primivies such as points, lines, and triangles having a single color. This is in part because their vertex and fragment shaders are very simple.
In this chapter, we focus on the vertex shader and the fancier things we can do with it. Recall from Section 7.3.2 that a vertex shader's main responsibility is to transform vertex attributes into clip space coordinates of the vertices. Because clip space coordinates dictates the shapes that the user see, we can draw more complicated shapes by putting more work into the vertex shaders. The programs in this chaper are examples on how to do exactly this.
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