OpenGL Programming Guide: The Official Guide to Learning OpenGL, Version 4.3, Eighth Edition

Tessellation Evaluation Shaders

The final phase in OpenGL’s tessellation pipeline is the tessellation evaluation shader execution. The bound tessellation evaluation shader is executed one for each tessellation coordinate that the primitive generator emits, and is responsible for determining the position of the vertex derived from the tessellation coordinate. As we’ll see, tessellation evaluation shaders look similar to vertex shaders in transforming vertices into screen positions (unless the tessellation evaluation shader’s data is going to be further processed by a geometry shader).

The first step in configuring a tessellation evaluation shader is to configure the primitive generator, which is done using a layout directive, similar to what ...