[ODE] three-body joints

[Gary R. Van Sickle]

> Hi everybody.  I'm wondering, what are the design issues that 
> caused Russ to implement only two-body joints?  It seems to 
> me that, from the point of view of the "big matrix", it's 
> just as easy to implement n-body joints.  For example, the 
> differentials used in cars can only be implemented as 3-body 
> joints.  No combination of 2-body joints will do.

Really?  I'm having a hard time coming up with a reason why; can you explain
further (or point me to a links)?

>  The equations for a differential are in the form e.g. c1 wA + c2 wB +
> c3 wC = 0, for bodies A, B, C.  What would it take to add 
> n-body joint support?

Somebody to code it up and maintain it.  I can't speak for Russ, but I'm
sure if it fit in well and was truly useful it would have a pretty fair
chance of at least getting into "contrib".

-- 
Gary R. Van Sickle