[ODE] iterative solver: testing needed

[Billy Zelsnack]

david@csworkbench.com wrote:
>>I can't seem to make test_crash.exe display anything except
>>the ground-plane and the ball-in-the-sky -- though it's
>>simulating something because it gets slower when I add more
>>cars or wall blocks!

The same thing happened for me. If I started with the old solver, the
objects were there. If I started with the new solver, they were not. If I
toggled to the new solver, they disappeared. The caterpiller worked though.
I was using vc6 btw. I was not using the latest stuff from cvs. Just the
.035 release.

Adam D. Moss wrote:
>It looks like I **may** have been confusing a friction problem
>with your Erroneously Sliding Things bug -- since a similar thing
>can be seen in test_boxstack using dWorldStepFast(), with just a
>few or as many as 40 iterations!  (About 1/4 of the bodies micro-
>jitter along the ground, looking like they're slowly sliding.)

I had a similar problem in my own weird (non opende) iterative solver. My
objects tended to slowly drive themselves around if they did not have any
objects on top of them to hold them in place. The problem was friction
based. If I removed the friction math all together, the objects sat still.
In reality it was not a big deal. Those objects could always just go to
sleep right away and that was easy enough to detect. Still it bothered me,
so I poked at it for awhile and ended up using a scalar ramp based on the
iteration number. Lone bodies still drives themselves around a tiny bit, but
it helped a lot.

-billy