[ODE] CFM and timesteps

[amundbørsand]

Hi,
I'm (still) playing with a leaf spring "approximation". It works okay,
but I have to use global CFM (and ERP) to allow the springs to flex
along it's length, that is, to let the hinges twist out of their hinge
axis (rotate (slightly) around other axis than the set hinge axis).
However, global CFM leads to a whole bunch of unwanted CFM, that is, my
car is rolling slightly when it's supposed to stand still, the wheels
can move on their axles and so on. Is there a way to separate this
without having to use global CFM? Or should I use ball joints with
AMotors (I've tried, but not quite got it working yet. How do I set it
up?)

Another issue is that I'm using real time, that is, the timestep is
never the same. That means I have to recalculate and set the CFM and ERP
values for all joints they apply to, as well as the global values, for
each frame. A problem with this (don't know if it's noticeable, though)
is that a lot of calculations in ODE "sees" one step into the future,
right? Won't that be wrong if next step is not the same size? Is there a
way to not have to set the ERP and CFM every frame, a way that is
automatically stepsize-dependent?


-- 
amundbørsand <amund@c2i.net>