Up: Rendering methods
The `PaperChain' representation finds all rings up to a user-defined
maximum size by walking the molecular topology, then proceeds to render
each ring by fitting a polyhedron to the involved atoms and the ring centroid.
The rings are drawn as bipyramids with a user-controlled height. The
rings are colored by pucker, using the Cremer-Pople pucker amplitude,
which is defined for all rings of three atoms or greater.