Figure 3 . There are many different ways of identifying the cycles in a graph. Geo3D uses an optimized version of this method so that only one visit of the graph is needed to identify a good set of cycles. A graph may contain many different cycles, but only a subset of them is needed to cover all the vertices that belong to a cycle. Figure 4 .
Every cycle is drawn, when possible, as a regular polygon in space.
When P is the first to be placed in a bunch of polygons, it can be drawn as a regular polygon centered in the origin. The choice depends on the length of the v x -v y segment and is needed to prevent the polygons from growing too much in size. Figure 5 . The new polygon P is drawn on a plane that forms a predefined angle a with the old polygon B . In some circumstances a cycle may have vertices in common with more than one polygon and the orientation of the new polygon may thus need to be chosen following a different rule.