[ODE] Preventing contacts between connected bodies

[Remi Ricard]

Hi Brett,
> Looking through the sample code I have noticed the following code in 
> the nearCallbacks:
>
> dBodyID b1 = dGeomGetBody(o1);
> dBodyID b2 = dGeomGetBody(o2);
> if (b1 && b2 && dAreConnected(b1, b2)) 
> return;
>
> and
>
> dBodyID b1 = dGeomGetBody(o1);
> dBodyID b2 = dGeomGetBody(o2);
> if (b1 && b2 && dAreConnectedExcluding (b1,b2,dJointTypeContact))
> return;
>  
> The benefit of the second is not completely clear to me.
This is useful if you want more than  one contact point between two 
bodies usually this may help stability.
If the joint are connected with something other than a contact joint you 
return.

>
> Also would it help to have a line:
>
> if(b1 == b2) return;
>
> for composite objects?
This is already done at a higher level.

Remi