Occlusion culling and z-fail for soft shadow volume algorithms

This paper presents a significant improvement of our previously proposed soft shadow volume algorithm for simulating soft shadows. By restructuring the algorithm, we can considerably simplify the computations, introduce efficient occlusion culling with speedups of 3–4 times, thus approaching real-time performance. We can also generalize the algorithm to produce correct shadows even when the eye is inside a shadowed region (using z-fail). We present and evaluate a three pass implementation of the restructured algorithm for near real-time rendering of soft shadows on a computer with a commodity graphics accelerator. However, preferably the rendering of the wedges should be implemented in hardware, and for this we suggest and evaluate a single pass algorithm.