[ODE] Inconsistent joints

[Jon Watte (ODE)]

Roland Plüss wrote:
>   dReal k = info->fps * erp;
>   info->c[0] = 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.

Cheers,

             / h+