Quadrangle

Quadrangle is a Surface defined by its boundary curves of an arbitrary type (except a circle). Curves do not have to be placed in a single plane, that is, in general, a Quadrangle can be a curved surface. This type of surface corresponds to a general surface with four corners, i.e., it is typically defined by four boundary curves (although this is not a necessary condition).

The Quad Surface can be defined either numerically or graphically.