[ODE] three-body joints

[Alen Ladavac]

If it's only about the differential, you should probably implement it as a
two body joint. As I understand it, the third body here (motor) is not
really a body in a usual simulation. I mean, you don't actually model the
engine, transmission, etc. directly with bodies and joints, do you? ;) Or do
you need differential joint for something other than powering a car?

Alen

----- Original Message -----
From: "Gary R. Van Sickle" <g.r.vansickle at worldnet.att.net>
To: <ode at q12.org>
Sent: Friday, September 10, 2004 01:49
Subject: RE: [ODE] three-body joints


> > 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
>
>
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