Chapter 6. Using Geometry and Tessellation Shaders

In this chapter, we will cover:

• Point sprites with the geometry shader
• Drawing a wireframe on top of a shaded mesh
• Drawing silhouette lines using the geometry shader
• Tessellating a curve
• Tessellating a 2D quad
• Tessellating a 3D surface
• Tessellating based on depth

Introduction

Tessellation and geometry shaders are relatively new additions to the OpenGL pipeline, and provide programmers with additional ways to modify geometry as it progresses through the shader pipeline. Geometry shaders can be used to add, modify, or delete geometry, and tessellation shaders can be configured to automatically generate geometry at various levels of detail and to facilitate interpolation based on arbitrary input (patches).

In this chapter, we'll look at several examples of geometry and tessellation shaders in various contexts. However, before we get into the recipes, let's investigate how all of this fits together.

The shader pipeline extended

The...