Collision detection algorithm for NURBS surfaces in interactive applications

Video games have reached a new level of realism. Programmable shading, 3D physics simulation and curved surfaces will soon become standard features. Real time collision detection, needed for this kind of application, is a difficult problem with no known optimal solution. We present a new algorithm for interactive collision detection between dynamic NURBS surfaces. It is intended to be used in real time applications, particularly in 3D video games embedded in an environment governed by simulated physical laws. This algorithm creates oriented bounding boxes (or OBB) on the fly with the surface control points and tests them for overlapping. If this test fails, the surfaces are subdivided into smaller NURBS surfaces and the algorithm is called recursively on these new surfaces. It stops when a certain precision level is reached, that is user definable as a function of the application. The results are the world space coordinates of the contact point, and the (u, v) parametric coordinates on both surfaces. The use of OBB allows for fast and memory efficient collision tests. The construction of an OBB with the surface's control points is simple and leads to a tightfitting bounding volume, which is the key of this fast collision detection algorithm.