Description

B-Spline patches must have 3 or 4 sides. Each patch is formed by a loop of intersections and the curve segments that lie between them, each curve segment producing a patch edge. Holes in the surface are often caused by too many or too few segments in a loop, preventing the creation of a patch. The exception is when all the curve segments lie within a plane. In this case a planar patch will be created, which can have more than 4 sides.