Interactive visibility ordering and transparency computations among geometric primitives in complex environments

Abstract

We describe a novel algorithm for visibility ordering among non-overlapping geometric objects in complex and dynamic environments. Our algorithm rearranges the objects in a back-to-front or a front-to-back order from a given viewpoint. We perform comparisons between the primitives by using occlusion queries on the GPUs and exploit frame to frame coherence to reduce the number of occlusion queries. Our visibility ordering algorithm requires no preprocessing and is applicable to all kind of models, including polygon soups and deformable models. We have used our algorithm for order-independent transparency computations in high-depth complexity environments and performing N-body collision culling in dynamic environments. We have implemented our algorithm on a PC with a 3.4 GHz Pentium IV CPU with a NVIDIA GeForce FX 6800 Ultra GPU and applied it to complex environments with tens or hundreds of thousands of polygons. Our algorithm can compute a visibility ordering among the objects and triangles at interactive frame rates.