The overdraw view mode have always been helpful to debug performance issues in every commercial/in-house engine i had a chance to use. Every engine would refer to it in a different name, or have it visually look slightly different. Regardless it is called “Quad Overdraw”, “Polygon Overdraw” or just “Overdraw”, it’s simply a representation on how many triangle draws taking place per pixel. So it made more sense that my implementation in Mirage to be called “Pixel Overdraw”. I also tried to make it as much customizable viewmode as possible, so I can always be sure i’ll get the best out of it. While most viewmodes are just a punch of simple shader code, The pixel overdraw is quite different, as the main trick behind the Pixel Overdraw, that you most of the time need to handle it using shader Atomics, or what would some people refer to it as “Atomic Images”, which is quite interesting part of GLSL and shaders in general.