The Winged-Edge Representation

Perhaps the oldest data structure for a b-rep is Baumgart's winged-edge data structure. It is quite different from that of a wire-frame model, because the winged-edge data structure uses edges to keep track almost everything. In what follows, we shall assume there are no holes in each face and later extend it to cope with holes. Moreover, we shall assume edges and faces are line segments and polygons. Topologically, one can always stretch curvilinear edges and faces so that they become flat without changing the relationships among them.