[ODE] iterative solver: testing needed

[gl]

> Right, but as soon as that external force is applied, those bottom joints
> would become crushed under the weight of the wall.... unless you disabled
> gravity until the wall crumbles, but that has its own problems.

I wasn't suggesting actually using ODE's fixed joints - rather making the
point that that's what they in effect were, until broken (as opposed to
merely resting boxes that may require a lot of contact point resolution when
enabled), and that there may be some way to optimize (read 'hack' ; ) this
scenario.  However, something like this may be better off being kept
app-specific - your approach sounds interesting and more generally useable.

> Well, I'll have to think on this one for a while (and get a verlet
> integrator running at some point), but I see a few problems.... a particle
> mesh is 2D, so you simulate the face of the wall, and have to have
> something to stabilize it.  There is no feedback for how much force
> (strain) is being placed on this particular constraint, other than how far
> off it is at the end of the iterations, but you could still use that as a
> break parameter.  I kind of have a feeling that you would end up ripping a
> seam straight up from the impact point, then the rest of the bricks on
> either side would flap around like.... cloth.  But I don't know without
> trying it, and I want to get the iterative solver completed, optimized,
> and integrated before I start on the next tangent.

Sure thing, I haven't fully thought it through, just throwing another
approach into the mix.  I'll be trying this sort of stuff myself eventually.

> http://graphics.ethz.ch/~muellerm/publications/fracture.pdf if you're
> interested...  Theirs is probably the method I would use at first glance,
> since deformable bodies are modeled as rigid bodies until they need to
> deform (or fracture).  It would be interesting to be able to shatter glass
> and warp plastic in ODE...

I'll check those out, thanks.

> There's just not enough hours in a day.

: )
--
gl