A face set provides the same flexibility as the patch set with regard to compact file size. It adopts the same principles of defining faces in a separate list to the vertices that they are composed of.
Figure 9.1: Face Set
<faceset id="face" use="face"> <vertices> <vertex>-90,-5,160</vertex> <vertex>-90,-5,-20</vertex> <vertex>90,-5,-20</vertex> <vertex>90,-5,160</vertex> <vertex>-85,0,155</vertex> <vertex>-85,0,-15</vertex> <vertex>85,0,-15</vertex> <vertex>85,0,155</vertex> <vertex>-90,-20,160</vertex> <vertex>-90,-20,-20</vertex> <vertex>90,-20,-20</vertex> <vertex>90,-20,160</vertex> </vertices> <face>7,5,6,</face> <face>8,5,7,</face> ... </faceset>
A big advantage to using the faceset element is that objects defined with other graphics packages export data using the same or similar formats.