"Peter Popov" <pet### [at] vipbg> wrote in message
news:jsfastgausb9ouu35jhbp7a5shefje1oi9@4ax.com...
> On Mon, 8 Oct 2001 19:28:36 -0400, "Redbeard \(MDJohnson\)"
> <red### [at] wvadelphianet> wrote:
>
> >I've been using Hugo Elias' page (http://freespace.virgin.net/hugo.elias/) as
a
> >reference for my simulations.  He's got some pretty good info, and if you
like
> >to explore he doesn't give you *too* much.
>
> Keep in mind that what is shown on Hugo's page is *the* most
> simplistic way of doing deformable body dynamics simulation. Linear
> mass-spring models are in general simpler than, say, finite element
> models, but the former can be made very realistic with introducing
> different improvements.
>
I do realize that (I was an engineering major and was exposed to some FEM) but
I'm not really looking for *super* realistic right now.  In fact, the animation
I was working for IRTC (which I still hope to finish, though not in time for the
contest) is going to use the gel to do a *very* unrealistic construction of a
bridge :-)

> As a start, I'd recommend reading anything you can find on the
> subject, esp. the works of Demetri Terzopoulos, David Baraff, Andrew
> Wittkin, James O'Brien and Chen Wu.
Thanks.  I'll check into them.

> >As for falling through the surface - I'm cheating right now.  If the
> >y-coordinate is less than 0 + radius of element, it's forced to that value.
> >When I start adding the ability to bounce off of surfaces I'll have to start
> >using trace and being *very* careful.
>
> Keep in mind that contact forces are *very* hard to model
> realistically. Collisions are even harder, as impulse propagation in
> this case is almost a stepwise process. In addition, inertia has to be
> taken into account.
Again, I'm not looking for full realism, just something that looks good in an
animation.  I will probably have to cheat at most steps by introducing abitrary
forces.  The sotrage format I'm using takes that into account.

> The geeky lingo above is to say that you can't just place some nodes
> on the surface they will collide with and expect realistic results.
Yep.

> Maybe I'm just jealous (gelous?). Again someone beat me to it :)
>
> Keep up the good work!
Thanks!  In fact, while I was away I figured out something that is wrong with my
model.  I hope to fix it over the weekend (now that beta 6 is out - thanks
Chris)

Michael

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