Solid Modelling Code?

[Michael Gleicher]

Just a whim but. . . . .

I'd like to play around a bit with some ideas about solid modelers. I was
hoping to experiment a bit before I dove in and started to design one.

Does anyone have some code to implement the basic functions for CSG models?
I'd really like to find something that could take a CSG tree (with the most
basic of primitives) and draw a picture of it (or give me a list of polygons
which I could send down the graphics pipe or convert to postscript).
I'd like to find a C or C++ or Lisp library, though if I could get the source
code to a whole modeller that I could play around inside of, that would be
great too. 

Failing this, I'd appreciate pointers to algorithms which would help me build
the simplest possible (get it up and flying quick) displayer for CSG models. 

(My interest is in user interfaces and the design process, not in solid
 modelling algorithms, so at this early stage, I'd like to avoid the latter as
 much as possible)

Thanks,

	Mike