METHOD AND SYSTEM FOR EFFICIENTLY TRIMMING A NURBS SURFACE WITH A PROJECTED CURVE

摘要

A curve (116, 200) projected onto a NURBS surface (118, 202) defines trim regions (120, 122, 124, 126, 128, 208) on the surface. Rays (142, 144) from a plurality of sample points (0, 2) are projected toward the surface (206). Intersections of the rays with the surface are mapped to the U, V domain (figure 8). Corresponding intersection points of adjacent rays are connected to define at least a portion of the trim region (256, 270, 272, 274, 276). Transitions on the surface are detected based upon differences in the number of intersections of adjacent rays (254, 268).