[ODE] Non-deterministic behavior

[Josh Welber]

Norman

         Actually, we have discovered that the problem with 
non-deterministic behavior was our own problem.  When we reset the state of 
the application we had allowed one integration step to happen between the 
call to reset and the actual resetting, so there would be a, very small, 
initial velocity on some objects left over from the previous run.  I am 
guessing that this may be the same issue with the crash test.  In any 
event, fixing that problem in our code fixed the determinism problem to.



At 02:25 PM 8/30/2003 +0900, nlin@nlin.net wrote:
>On Sun, Aug 24, 2003 at 10:16:30AM -0400, Josh Welber wrote:
> > Does anyone have experience with ODE giving non-deterministic
> > results?
>
>As a comment I'd like to point out that test_crash.exe (the stepfast demo)
>gives non-deterministic behavior. You can press "r" to reset the simulation,
>yet if you press "r" several times, the car(s) crash into the wall in 
>different
>ways each time. I don't know if this is due to stepfast or ODE or a flaw
>in test_crash.cpp, but it's worth investigating.
>
>-Norman

Josh Welber
partner/tech wrangler
Large Animal Games
http://www.largeanimal.com
t: 212.989.4312
f: 305.489.5790