The Open Dynamics Engine (ODE) is a free, industrial quality library for 
simulating articulated rigid body dynamics. Proven applications include 
simulating ground vehicles, legged creatures, and moving objects in VR 
environments. It is fast, flexible and robust, and has built-in collision 
detection.

NOTE: You must use "su -" instead of "su" to build this (or you can 
      source /etc/profile after plain 'su') so that /usr/X11R6 is in $PATH