Geometric Modeling

EusLisp adopts Brep (Boundary Representation) as the internal representation of 3D geometric models. Components in Breps are represented by classes edge, plane, polygon, face, hole, and body. Primitive body creating functions and body composition functions create new instances of these classes. In order to use your private geometric classes having more attributes, set special variables *edge-class*, *face-class* and *body-class* to your class objects.

Figure 9: Arrangements of vertices, edges, and faces