[ODE] A 'real' demo of ODE

[Russ Smith]

> As forces in individual rods do make sense in car simulations (force
> feedback effects, suspension compliance and breaking) it would be
> quite appropriate to model each such link separately.

a single joint that captured the kinematics of the situation would be
faster, but obviously it is not a simple joint to create. when i was
at mathengine we looked at the problem a bit, the goal was to have
a unified way of creating joint constraints from various pieces, so
for example we could just specify that "the joint has these links" and
the resulting constraint would be properly computed. some headway
was made, but the problem is that real joints have too many exceptions
to a unified scheme. so we just did it the hard way. this is an area
where some very useful work could be done.

> One thing I wanted to ask, though; does ODE support time varying
> constraints (where constraint functions depend explicitly on time)?

sort of, yes - you can easily vary the constraint parameters per
timestep, and bias the error reduction terms to compensate for the
various extra d/dt terms you will get in the constraint - so in the end
you can achieve this.

p.s. i have not yet had a chance to look at your "pseudo-algorithm"
yet gregor, too busy...

russ.

--
Russell Smith
http://www.q12.org