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

Geometry Amplification

As you have read, it is possible for a geometry shader to output a different amount of primitives in than it accepts as input. So far we have looked at a simple pass-through geometry shader and at a shader that selectively culls geometry. Now we will look at a shader that produces more primitives on its output than it accepts on its input. This is known as amplification. Amplification can be used to implement fur shells or moderate tessellation, for example (although tessellation is best left to fixed-function tessellation hardware). Also, in combination with layered rendering or viewport indices, the geometry shader can produce several versions of the same geometry as slices of an array texture or different regions of ...