Unity Game Optimization - Third Edition

Fill Rate

Fill Rate is an inclusive term referring to the speed at which the GPU can draw fragments. However, this only includes fragments that have survived all of the various conditional tests we might have enabled within the given fragment shader. A fragment is merely a potential pixel, and if it fails any of the enabled tests, then it is immediately discarded. This can be an enormous performance-saver, as the Rendering Pipeline can skip the costly drawing step and begin working on the next fragment instead.

One such example of a test that might cull a fragment is Z-testing, which checks whether the fragment from a closer object has already been drawn to the same fragment location (the Z refers to the depth dimension from the point of ...