[ODE] ODE and geom scales

[Jon Watte]

>  upForce = -Gravity * (DesiredHeight / distanceSoon) * BodyMass;

Btw: the 1/ relationship is less stable than a 1- relationship, 
because it reacts harder to really deep penetrations. It will 
not be stable unless you use a fixed time-step. But you should 
be using a fixed time-step anyway, so that's probably not a 
problem for you :-)

A more stable, less directly responding formulation is the 
classic spring:

  upForce = -Gravity * (DesiredHeight - distanceSoon) * BodyMass * SpringConstant;
  if( upForce < 0 ) upForce = 0;

Cheers,

			/ h+