[ODE] patch - position-correcting constraints

[Graham Fyffe]

Doesn't the patch take away the ability to simulate springs using hi /
low stops?  And if so, would it be easy to add a flag to the joints in
question to determine whether they should be considerd real hard
position stops, or just springs with CFM / ERP?

- Graham



On 5/1/05, Geoff Carlton <gcarlton at iinet.net.au> wrote:
> I've recently had tweak of the max correcting velocity and the
> penetration depth layer.  These two settings allow a huge increase in
> the quality of the object collisions, and also seem to reduce the random
> noise in the bounces that makes falling boxes un-stackable.
> 
> As a result, the priority of the issue has dropped for me, though I'm
> still curious about any solution that improves the way ode handles
> penetration in the solver.
> 
> Geoff
> 
> Adam D. Moss wrote:
> 
> > Megan Fox wrote:
> >
> >> The point is that, at present, bodies are de-penetrated by forces.
> >> These forces are in no way separate from others, and stack on
> >> eachother with each frame, leading to explosions after stack apon
> >> stack apon stack of depenetrating force has its way.
> >
> >
> > That's certainly an issue, I think, but the underlying issue is that
> > once that corrective force has served its purpose it still remains
> > in effect, which causes both correction-accumulation and the fake-
> > bounce effect.
> >
> >> The patch, in theory, removes that problem, de-penetrating objects at
> >> a set, reasonable velocity.
> >
> >
> > In a round-about way, yes. :)  What it does is remember, within an
> > island's step, how much of a body's corrective force is only being
> > applied to correct interpenetration, then it removes that much force
> > again once the force has affected the position for that step.  So in
> > effect it makes the effects of interpenetration-correction not extend
> > beyond the current step (any remaining interpenetration will
> > cause further correction in the next step, of course), which amounts
> > more or less to a position correction.
> >
> > > This should remove any sort of physical
> >
> >> explosion due to penetrating bodies, and might even make stacking
> >> behavior a bit better (maybe?).
> >
> >
> > It doesn't seem to much affect stacking either way, sadly.
> >
> >> Apologies on my part, I've been too busy to try your patch - looks
> >> great, but I need to keep my codebase consistent for now
> >
> >
> > I understand!
> >
> > --adam
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> >
> >
> >
> 
> 
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