Gergely Vandor wrote:
> 
> >The main reasons why the bar is that soft are that i did not yet implement
> >higher order integration methods and less stiff systems are better for
> >testing things because these are less likely to cause problems with the
> >numerics.
> >
> 
> I'm not sure. Check this one:
> http://www.progressive.hu/gero/drum.m1v
> 
> This is one of the first animations I made using springs. Maybe it's
> accidental, or maybe it's because it is very simple, but it looks quite OK
> to me, and it is almost totally rigid. I used euler too, and maybe 20
> steps/frame.

You seem to use quite strong overall damping (and not just damping
parallel to the springs) which usually weakens the problems with large
time steps.  Try turning off the damping and you will probably see how
everything explodes.

I also suppose you are using collision equations for the the interaction
with the environment which is insensitive towards large time steps.

> BTW, I'm glad you are making this patch, I'm just sorry it's not ME who is
> doing it. :) I would be probably doing something similat if I wasn't so
> lazy to learn C some more. :) Oh, did I mention the anim is amazing? Will
> the source be available?

Yes, once i have time to get it in a publishable state with documentation
and sample scenes.

Christoph

-- 
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Last updated 13 Aug. 2002 _____./\/^>_*_<^\/\.______

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Christoph Hormann wrote:
>

>
>You seem to use quite strong overall damping (and not just damping
>parallel to the springs) which usually weakens the problems with large
>time steps.  Try turning off the damping and you will probably see how
>everything explodes.

Maybe I'll check if I find the pov file.

>
>I also suppose you are using collision equations for the the interaction
>with the environment which is insensitive towards large time steps.
>

I really don't know what you mean by this, so I can't tell. :(

>> BTW, I'm glad you are making this patch, I'm just sorry it's not ME who is
>> doing it. :) I would be probably doing something similat if I wasn't so
>> lazy to learn C some more. :) Oh, did I mention the anim is amazing? Will
>> the source be available?
>
>Yes, once i have time to get it in a publishable state with documentation
>and sample scenes.

Great! Any plans for fluids? Some time ago I made a basic anim with van der
Waals forces and 50 "atoms". I believe that a similar system is used in
fluid dynamics programs like RealFlow (with much more particles and
probably many tweaks). It was pretty easy to modify my spring scenes to
this:

http://www.progressive.hu/gero/small.mpg

(Sorry if you've alredy seen it, and it's 1.5 MB.)

Gergely

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