Semantic Based Shader Generation Using Shader Shaker

Authors: Julien Hamaide, Ramsès Ladlani, Michael Delva

Maintaining shaders in a production environment is hard, as programmers have to manage an always increasing number of rendering techniques and features, making the amount of shader permutations grow exponentially. As an example, allowing six basic features, such as vertex skinning, normal mapping, multitexturing, lighting, and color multiplying, already requires 64 shader permutations.

Supporting multiple platforms (e.g., HLSL, GLSL) does not help either. Keeping track of the changes made for a platform and manually applying them to the others is tedious and error prone.

This chapter describes our solution for developing and efficiently maintaining shader permutations across multiple target platforms. The proposed technique produces shaders automatically from a set of handwritten code fragments, each responsible for a single feature. This divide-and-conquer methodology was already proposed and used with success in the past, but our approach differs from the existing ones in the way the fragments are being linked together. From a list of fragments to use and thanks to user-defined semantics that are used to tag their inputs and outputs, we are using a pathfinding algorithm to compute the complete data flow from the initial vertex attributes to the final pixel shader output….