[ODE] stress testing and box stacking instability

[Anselm Hook]

Hi Dave,

I thought everybody knew about this defect by now?  It's something that
Russ has said he's going to fix for the next big release.  If the bug
hasn't changed then basically it is just that not enough contacts are
being generated between two box surfaces - there needs to be at least 3
but there is only 1 right now.

 - a


On Fri, 22 Nov 2002, David McClurg wrote:

> I'm trying to use stacked boxes in my game and I ran into the box
> stacking instability mentioned previously on this list.  That got me
> to reading the Gamasutra article "Product Review of Physics Engines,
> Part One: The Stress Tests" and I thought it might be useful to put
> together the stress test suite for ODE.
>
> It was easy to get tests 1-6 coded and the only one that did badly was
> Test 2: "A slightly larger cube is dropped on a smaller cube.  This
> was a variation on the first test in that the difference between the
> cubes' sizes was much smaller.  This test was meant to be a "gimme"
> and should just work."  Expected result: cubes should drop straight on
> top of each other and come to immediate rest.
>
> I attached a modified test_boxstack.cpp which shows what happens.  The top box dances around for a long time and eventually falls off the top box.  In Havok, i think they might be freezing/sleeping boxes in this situation.  Does the solution lie in proper detection of this situation or in better contact generation?
>  <<test_boxstack.cpp>>
>