[ODE] Inconsistent joints
roland at rptd.dnsalias.net
Fri Sep 1 11:07:59 MST 2006
> Roland Plüss wrote:
>> dReal k = info->fps * erp;
>> info->c = k*j->contact.geom.depth;
>> It is assumed that the depth is recovered gradually over the entire
>> simulation step but this is not true. After the "New Joint Guide" the
>> c-value in the contact joint is calculated like this:
>> c = ( ERP / s ) * nT * [ ( p1 + a1 ) - ( p2 + a2 ) ]
> ERP/s is the same as the "k" calculated in the code.
> It appears nT happens to be 1 for the contact joint.
> ((p1+a1) - (p2+a2)) is the same as contact.geom.depth for the case of
> the collsion joint.
> So, what's the difference you're implying? ODE is a first-order
> integrator, so it doesn't use multiple derivatives for a single step,
> like you'd see in something like R-K4.
> / h+
With nT I tried to reference the 'contact normal' btw. Judging from the
multi-stepper I thought the joint constraints are checked more than once
for one simulation step ( dWorldQuickStep ). So the constraint force is
calculated only once per simulation step and not per interval?
Leader and Head Programmer
- Game: Epsylon ( http://epsylon.rptd.dnsalias.net/ )
- Game Engine: Drag(en)gine (
- Normal Map Generator: DENormGen (
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