TODO: Particle systems described at
http://www.sgi.com/software/opengl/advanced98/notes/node151.html

TODO: TrueType font rendering in OpenGL:
http://gltt.sourceforge.net/about.html

TODO: Better tree rendering
http://cedar.intel.com/cgi-bin/ids.dll/content/content.jsp?cntKey=Generic+Editorial%3a%3aimposters&cntType=IDS_EDITORIAL&catCode=0&path=1

