Fairly recently I created and ArcBall module in pyprocessing, and I wondered if could I translate it to work with processing.py ( the reason this could be considered heresy is that the excellent peasycam library, and processing.py are both written by Jonathan Feinberg). I've published the ArcBall with my other processing.py experiments at github for anyone interested. The interesting thing I learned was that it is possible to import elements from processing into a module (for ruby processing this is possible but best achieved via a proxy mixin).