Non-interleaved Deferred Shading of Interleaved Sample Patterns

Abstract

This paper presents a novel and fast technique to combine interleaved sampling and deferred shading on a GPU. The core idea of this paper is quite simple. Interleaved sample patterns are computed in a non-interleaved deferred shading process. The geometric buffer (G-buffer) which contains all of the pixel information is actually split into several separate and distinct sub-buffers. To achieve such a result in a fast way, a massive two-pass swizzling copy is used to convert between these two buffer organizations. Once split, the sub-buffers can then be accessed to perform any fragment operation as it is done with a standard deferred shading rendering pipeline. By combining interleaved sampling and deferred shading, real time rendering of global illumination effects can be therefore easily achieved. Instead of evaluating each light contribution on the whole geometric buffer, each shading computation is coherently restricted to a smaller subset a fragments using the sub-buffers. Therefore, each screen pixel in a regular n×m pattern will have its own small set of light contributions. Doing so, the consumed fillrate is considerably decreased and the provided rendering quality remains close to the quality obtained with a non-interleaved approach. The implementation of this rendering pipeline is finally straightforward and it can be easily integrated in any existing real-time rendering package already using deferred shading.