ABSTRACT
Sometimes there are shapes a designer wants to attain with surfaces which cannot be modeled easily as a single tensor product B-spline, nor in fact a single surface patch in any form, be it explicit, implicit, parametric, or over rectangular or triangular domain. In these situations it is sometimes possible for the designer to model the shape as a compound shape, modeling each part as a B-spline (or more restrictive Bézier) surface. Sometimes only stylized versions of those shapes can be modeled in that way, but real parts designed to specification cannot be. Sometimes, not even stylized parts can be modeled that way. In these situations, Boolean operations are frequently useful.
