[ODE] Step fast issue?

[Amund Børsand]

I've had very little success with stepfast for some reason. I don't know
if this has anything to do with your problem, but you made me think of
it :)

I have my ODE GUI editor, "4link", and have built a few cars with it,
all of then with quite different suspension setups. Only similarities
are the dimensions and weights, all measure about two units wide, four
to five units long, and weigh between one and three units. However, they
all have parts weighing down to 1/100 unit. I don't know if this last
part is what screws it up, or if it's just the complexity, or if it has
something to do with ERP and CFM values, though I have tried adjusting
them as well... my cars only fall into a blob on the ground, the main
body (with no collision geometry) hanging about 1 unit below the ground,
while all the wheels make a lump above it. My rigid axles are also not
rigid anymore, just floating around between the wheels. I have tried up
to 100 iterations, making little difference.

I haven't seen any obvious explanations to why this shouldn't work, is
it because of my (too) wide range in mass and dimensions between objects,
or is it just too complex for stepfast?

Those interested can test it in my program, just load a car, choose
physics/world settings and then stepfast, apply and play the scene.


"DjArcas" <djarcas at hotmail.com> skreiv:

> I haven't managed to make any difference to this so far. I'm going to
> attempt to change the balljoints to hinge joints tonight, to see if that
> helps.
> 
> Still no suggestions?
> 
> Adam
> 
> ----- Original Message ----- 
> From: "DjArcas" <DjArcas at hotmail.com>
> To: <ode at q12.org>
> Sent: Sunday, February 29, 2004 9:49 AM
> Subject: [ODE] Step fast issue?
> 
> 
> > I've been using with normal Step for a while now, and I've just gone
> across
> > to stepfast. Generally speaking, it's briliant, fantastically fast.
> >
> > However, I seem to have run into a situation where the physics simulation
> > just breaks when using step fast.
> >
> > I have a box, with another box attached to it, and a sphere attached to
> that
> > box, like this:
> >
> > ||||||
> >   |
> >   |
> >  O
> >
> > They are attached using ball joints, in a Thrust sort of a style. I am
> then
> > using the Plane2d joint on these.
> >
> > If the sphere collides with another object, I create a ball joint between
> > the sphere and the collided object - allowing the 'ship' to carry objects
> > around.
> >
> > This works perfectly with dWorldStep, but if I use dWorldStepFast1, what
> > happens is that the sphere detaches, and sits half way between the cable
> and
> > the attached object. The attached object doesn't move. I've tried
> iterations
> > all the way up to 360 with no success.
> >
> > If I comment out dWorldStepFast1 and uncomment dWorldStep, it works
> > perfectly.
> >
> > Ideas? (I'm totally stumped! :)
> >
> > Thanks in advance,
> >
> > Adam
> > _______________________________________________
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> > http://q12.org/mailman/listinfo/ode
> >
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-- 
Amund Børsand <amund £ offroad . no>