Patent
1992-10-15
1994-10-18
Nguyen, Phu K.
G06F 1500
Patent
active
053576004
ABSTRACT:
A system and method is provided to perform quick patch level tests in a timely manner. The normal function of the patch is first computed using the convex hull property of the patch. The control points, which indicate the direction of the normals of the normal function, are used to construct a floating cone. This cone contains all the normals to the given patch. The floating cone is then moved in space and is truncated by two parallel planes orthogonal to the cone axis to contain the original given patch. From this information, frontfacing and backfacing volumes are constructed. These volumes are then used to derive information about the patch that can speed up its processing. For example, culling may be performed on the patch level before tessellation into triangles. The time consuming operations of computing normals and the floating cone are performed at the creation time of the patch and are view independent. Therefore, for subsequent views of the same patch, the same cone of normals may be used to determine whether the patch is frontfacing or backfacing, providing substantial time savings in processing.
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Abi-Ezzi Salim S.
Shirman Leon A.
Nguyen Phu K.
Sun Microsystems Inc.
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