“Screen space classification for efficient deferred shading” by Hutchinson, Knight, Ritchie, Parrish and Moore

Deferred shading is an increasingly popular technique for video game rendering. In the standard implementation a geometry pass writes depths, normals and other properties to a geometry buffer (G-buffer) before a lighting pass is applied as a screen space operation. Deferred shading is often combined with deferred shadowing where the occlusion values due to one or more lights are gathered in a screen space shadow buffer. The universal application of complex shaders to the entire screen during the shadow and light passes of these techniques can contribute to poor performance. A more optimal approach would take different shading paths for different parts of the scene. For example we would prefer to only apply expensive shadow filtering to known shadow edges. However this typically involves the use of dynamic branches within shaders which can lead to poor performance on current video game shading hardware.

1. Swoboda, M. 2009. Deferred Lighting and Post Processing on PlayStation®3. Game Developers Conference 2009.
2. Moore, J., Jefferies, D. 2009. Rendering Techniques in Split/Second. Advanced Real-Time Rendering in 3D Graphics and Games — SIGGRAPH 2009.