The algorithm utilizes this coherence by caching the contact information from the previous step to perform incremental computations. It is applicable to general polygonal models and needs no topological information. Given two models, PQP supports a number of diffeent queries. It makes use of swept sphere volumes as the choice of BV for distance queries. Futhermore, it allows the client progam the flexibility of using more than one bounding volume for a given query.
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If the list it etuns is an empty list, then the models do not touch. To process a pair of models, the client program must explicitly call a collision procedure, passing those two models and their placements. But it exploits the special characteristics of convex polytopes to very quickly determine contact status. It also exploits temporal coherence, so that collision query times are extremely fast when the models are moved only a relatively small amount between frames. So, objects may be added and deleted from the managed set wheve the client wishes.