Primitives of b-rep Scheme
The building blocks for b-rep. models are :
Vertex
It is a unique point (an ordered triplet) in space.
Edge
An edge is a finite, non-self-intersecting, directed space curve bounded by two vertices that are not necessarily distinct.
Face
A face is defined as a finite connected, non-self-intersecting, region of a closed oriented surface bounded by one or more loops.
Loop
A loop is an ordered alternating sequence of vertices and edges.
Genus
It is the topological name for the number of handles or through holes in an object.
Body (or Shell)
It is a set of faces that bound a single connected closed volume. A minimum body is a point. Topologically this body has one face, one vertex, and no edges. It is called a seminal or singular body