This appendixsection describes the geometry representations of the data used by Creo Object TOOLKIT C++.

A surface in Creo contains data that describes the boundary of the surface, and a pointer to the primitive surface on which it lies. The primitive surface is a three-dimensional geometric surface parameterized by two variables (u and v). The surface boundary consists of closed loops (contours) of edges. Each edge is attached to two surfaces, and each edge contains the u and v values of the portion of the boundary that it forms for both surfaces. Surface boundaries are traversed clockwise around the outside of a surface, so an edge has a direction in each surface with respect to the direction of traversal.

This section describes the surface parameterization. The surfaces are listed in order of complexity. For ease of use, the alphabetical listing of the data structures is as follows: