Face-Edge Relationships – Rings
Ring – a sequentially connected set of edges that bound a face
- Outer Ring (counterclockwise) – defines the outer boundary of a face
- Includes any edges within the face, but connected to the outer boundary
- Inner Ring (clockwise) – defines an inner boundary of a face (i.e., a "hole")
- A collection of edges that are connected to one another, but not connected to the outer boundary, form an inner ring, even if they do not enclose an area
- An inner ring need not contain any faces - it may represent a real hole
An edge can appear twice in the same ring, once in each orientation