Torus:

Schemes depend on sweep representation are useful in making solid models of 2½ - objects. The class of 21½ - D objects involved both solids of uniform thickness in a given direction and symmetric solids. The former are known as extruded solids and are built up via linear or translational sweep; the latter are solids of revolution which may be created via rotational sweep. Sweeping is utilized in general as a means of entering object descriptions into b-rep or c-rep based modellers. Sweeping is depends on the notion of moving a point, curve or a surface along with a given path. There are three kinds of sweeps: linear, nonlinear, and hybrid sweeps, as defined below: