Adding a few notes on libraries that may be worth investigating to see if they
have parsing logic that would help in developing convertors for various formats.
They may amount to nothing, but are worth checking.


Collada (MIT licensed libraries)
http://opencollada.org/
http://sourceforge.net/projects/colladamaya/ (specifically,
http://colladamaya.svn.sourceforge.net/viewvc/colladamaya/trunk/FCollada/)

Inventor files: (LGPL license)
http://oss.sgi.com/projects/inventor/
http://www.mevislab.de/inventor/ (website changed, see src/libgcv in dmtogl 
                                  branch of BRL-CAD for patch)
http://fl-inventor.sourceforge.net/

AutoCAD dwg - none (opendwg not compatible with BRL-CAD licensing)

Solidworks (.sat, .sldprt, .sldasm)
No external libraries apparent, probably unlikely
src/external/Cubit/g-sat.cpp should be  useful as a starting point.

Parasolid/UGS
No external libraries apparent, probably unlikely

POV-RAY
Haven't found anything with a compatible license...

Blender
Apparently their file format is a bit... weird.  Possibly useful notes here:
http://www.atmind.nl/blender/mystery_ot_blend.html
http://www.blender.org/development/architecture/
http://www.blender.org/development/architecture/notes-on-sdna/
Since blender is GPL, unlikely their code can be used directly. Since their
storage format seems to be close to their data structures, it might be worth
contacting the project and asking specifically about the parsing code, if they
have the flexibility to sub-license just that piece as LGPL.

Update: From discussions at SIGGRAPH Blender forum, unlikely they have flexibility to
relicense anything.  Much more interestingly, Gamekit was announced there which DOES
import Blender files and is MIT licensed:

http://code.google.com/p/gamekit/

Exporting Blender may be impractical (i.e. no well defined format to target) but as Blender
has importers for a wide variety of formats exporting to Blender directly may not be necessary

Universal 3D (Apache 2.0 license)
http://sourceforge.net/projects/u3d/

PLY
http://www.tecgraf.puc-rio.br/~diego/professional/rply/ (newer, probably should start here)
http://www.cc.gatech.edu/projects/large_models/ply.html


VRML/X3d  (LGPL license)
http://openvrml.sourceforge.net/
http://sourceforge.net/projects/x3dtoolkit/

