Geometry Traversal
This section illustrates the relationships between faces, contours, and edges.
Overview
Note the following:
•  A simple rectangular face has one contour and four edges.
•  A contour will traverse a boundary such that the part face is always on the right-hand side (RHS). For an external contour, the direction of traversal is clockwise. For an internal contour, the direction of traversal is counterclockwise.
•  If a part is extruded from a sketch that has a U-shaped cross section, there will be separate surfaces at each leg of the U-channel.
•  If a part is extruded from a sketch that has a square-shaped cross section, and a slot feature is then cut into the part to make it look like a U-channel, there will be one surface across the legs of the U-channel. In other words, the original surface of the part is represented as one surface with a cut through it.
•  Geometry traversal happens on body, solid surface and contour. For quilts, datum curves, edges, the geometry traversal will happen through a solid. To collect all the bodies in a specified solid, use the function ProSolidBodiesCollect().
To Walk Through the Geometry of a Block
1. Walk through the surfaces of a body, using ProSolidBodySurfaceVisit().
2. Walk through the surfaces of a solid, using ProSolidSurfaceVisit().
3. Walk through the contours of each surface, using ProSurfaceContourVisit().
4. Walk through the edges of each contour, using ProContourEdgeVisit().
Geometry Terms
Consider the following definitions:
•  surface—An ideal geometric representation, that is, an infinite plane.
•  face—A trimmed surface. A face has one or more contours.
•  contour—A closed loop on a face. A contour consists of multiple edges. A contour can belong to one face only.
•  edge—The boundary of a trimmed surface.
An edge of a solid is the intersection of two surfaces. The edge belongs to those two surfaces, hence to two contours. An edge of a datum surface can be either the intersection of two datum surfaces, or the external boundary of the surface. If the edge is the intersection of two datum surfaces, it will belong to those two surfaces (hence, to two contours). If the edge is the external boundary of the datum surface, it will belong to that surface alone (hence, to a single contour).
Examples 1 through 5 show some sample parts and list the information about their surfaces, faces, contours, and edges.
Example 1
Image
This part has 6 faces.
•  Face A has 1 contour and 4 edges.
•  Edge E2 is the intersection of faces A and B.
•  Edge E2 is a component of contours C1 and C2.
Example 2
Image
Face A has 2 contours and 6 edges.
Example 3
Image
This part was extruded from a rectangular cross section. The feature on the top was added later as an extruded protrusion in the shape of a semicircle.
•  Face A has 1 contour and 6 edges.
•  Face B has 2 contours and 8 edges.
•  Face C has 1 contour and 4 edges.
Example 4
Image
This part was extruded from a cross section identical to Face A. In the Sketcher, the top boundary was sketched with two lines and an arc. The sketch was then extruded to form the base part, as shown.
•  Face A has 1 contour and 6 edges.
•  Face B has 1 contour and 4 edges.
•  Face C has 1 contour and 4 edges.
•  Face D has 1 contour and 4 edges.
Example 5
Image
This part was extruded from a rectangular cross section. The slot and hole features were added later.
•  Face A has 1 contour and 8 edges.
•  Face B has 3 contours and 10 edges.