[ODE] processing islands in different order
tomyeh at CS.UCLA.EDU
Fri Aug 25 01:31:34 MST 2006
Well, the position data starts diverging even in the first frame.
I've turned off the flags that result in non-deterministic behavior such as
REORDER_CONSTRAINTS and RANDOMLY_REORDER_CONSTRAINTS.
If I run the default ode(with the above flags turned off) , I can
reproduce exact results.
I am just trying to understand the engine better, so that I don't break
it with my modifications.
if anyone has an idea please let me know.
On Fri, 25 Aug 2006, Bram Stolk wrote:
> Thomas Yeh wrote:
> > I am seeing the behavior that if islands are processed in a different
> > order than the default ordering, the position data for the objects in the
> > simulation are slightly different. I am using 0.5, and I generate all the
> > islands before I start calling the stepper function.
> > Can anyone explain this behavior? As far as I know, the islands'
> > computations should all be independent right?
> Do you mean that after many iterations (seconds), the result diverge?
> That is to be expected.
> As a matter of fact, simulations in ODE are not even reproducible
> (at least not on x86)
> Take e.g. test_basket from the ode tests... for me, sometimes
> it is a miss, sometimes it scores a basket.
> > thx
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