Modules
a package containing 3D points, vectors, areas, objects and links
an area (or space) in 3D space
link two or more objects together by a signal-relay chain
an 3D objcet which lives (or is dead)
marks a point in the 3D world
an 3D object with mass
a point in 3D space
export the signal and state names
base class for virtual and physical 3D objects
an 3D object which can trigger some event if someone enters