World Simulator
From SpaceElevatorWiki.com
Torcs 3D Engine.
It's almost pure OpenGL, so very easy to tweak.
Main work is done in src/modules/graphic/ssggraph/grmain.cpp
It builds a list of "screens" (main screen, mirrors, etc)
Each screen set up the opengl parameters he like and render track, then cars, etc..
Rendering of the car is done here: src/modules/graphic/ssggraph/grcar.cpp, grDrawCar()
