Hi Paul,

  I suggested adding the path to sys.path in your Chimera start-up so that you wouldn’t have to modify the system Python.

  Here is a Python example of computing a triangulation for the part of a plane inside a closed surface, using as an example an icosahedron for the closed surface.  You can just use File / Open… in Chimera to run it and it will report in the Reply Log (menu Favorites)

Clipped icosahedron, clip plane has 10 triangles

More Python code examples are on the Chimera Python scripts web page:

  The Chimera programming documentation is scant.  To figure out how to write the attached example code I looked at my Chimera distribution at file

Chimera.app/Contents/Resources/share/SurfaceCap/surfcaps.py

at the calculate_cap() routine.  All of the Chimera Python modules are in the above “share” directory — it is useful to poke around in there to figure out how things work, although it can be hard to find what you want.

Tom