[ODE] contact joint

[Konstantin Voloshin]

Hello

Penetration depth is joint error for a contact joint.
It participates in evaluation of ammount of force,
required to correct the error.

Even if you always set depth to zero (and do not
use too big CFM) your bodies will not pass through
each other. There will just be no force applied to
reduce the penetration depth of already penetrating
bodies. The other force, which prevent penetration
gepth from growing, will still be there. Due to precision
issues, your bodies still could in time go through each
other, but not as there is no collision at all.

There're at least 3 numbers you'll have to play with,
if you want to customize contact - ERP / CFM / timestep.
If you'll use constant penetration depth, that would be
another number to adjust in mutual dependence with
others.

I would suggest you to use the biggest value, which doesn't
cause noticeable jumping of bodies which should actually
rest. However, I'm sure that much better suggestion is to
evaluate the penetration depth.

SY, VolK


----- Original Message ----- 
From: "Vasco Lohrenscheit" <v.lohrenscheit at collision-studios.com>
To: <ode at q12.org>
Sent: Monday, December 15, 2003 6:35 PM
Subject: [ODE] contact joint


Hello,

I want too use ODE with another collision library (from the gamebryo
engine). For a contact joint you need the penetration depth of the two
colliding bodies but unfortunately the collision library doesn't provide
this information. Are there stable work around / fakes possible other than
using opcode ? For example, would it be safe to give always some fixed
penetration depth value ? What magnitude should that be ? Or any other
possibilities ?

    best regards,

         Vasco Lohrenscheit