Using Graphics Hardware to speed-up your visibility queries

Our visibility method is designed to solve two types of visibility queries: point-based visibility queries, where several visibility queries share the same origin,
and plane-based visibility queries, where several visibility queries have their origins on the same plane. Both occur frequently in global illumination algorithms.
Combining the speed given by graphics hardware with a software heuristic to avoid reliability problems, our visibility method is significantly faster than
ray-casting, and still gives the same results.