[ODE] Non-wrapping hinge angle measurement

[Ross L. Hatton]

Hi all,

I'm looking at adding a non-wrapping angle measurement (angular 
displacement rather than direction) to my hinge joints.  Anyone done 
this before and have code lying around for it?  I've got a couple ideas 
for how to go about this, but if someone's already got a good solution 
handy, I'd prefer not to build it over from the ground up.

-Ross Hatton