Introduction to Low Level GLSL Optimisation

This guide describes ways to optimise OpenGL Shading Language (GLSL) code for PowerVR Rogue architecture. These optimisations are low-level, and therefore can be used to get the last ten percent of performance boost from the hardware. Before using these techniques, it is essential to make sure that the most optimal algorithms are being used, and that the GPU is well utilised.

The effectiveness of these optimisations may vary depending on the exact compiler architecture used. It is always worth checking if optimisations result in a performance improvement on the target platform. Throughout the document there are examples of USC instructions the GLSL code compiles to.

This document is based on the following:

Low-Level Thinking in High-Level Shading Languages, by Emil Persson.

Low-Level Shader Optimisation for Next-Gen and DX11, by Emil Persson.