[ODE] Lots of stacked boxes/breaking constraints (was Re: Inside ODE)

[Russ Smith]

> The problem is that collision detection finds a limited number
> of intersecting points, which is merely an approximation
> to the contact configuration. (For boxes, I think a max. of 3
> points are returned.)

actually, the default ODE box-box collider *should* return a
maximum of 3 points, but currently only returns a maximum of 1
point (the lazy programmer has not got around to fixing this
yet). so you will get even more instability for your money
in a stacked-boxes system. incidentally, this is why a stacked
box wall works better if the boxes don't touch each other in the
same row - if they did then the single box-box contact will
sometimes be used for horizontally adjacent boxes and will not
help keep the stack up.

> Question to Russ ... Would it be possible to set up a stable
> box stack with a grid of joints between adjacent boxes which
> had a very low breaking threshold?

it's possible, but there are better solutions i think. the best
solution is to complete the box-box collider (as above). another
solution is to inactivate all the boxes in the wall - so they
wont move at all until something hits them.

> Would such a large number of joints be computationally 
> manageable?

"it depends" (TM).

russ.

--
Russ Smith
http://www.q12.org