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These cloth animations of yours are truly amazing!
This one, as many others have said, is a tad too stretchy, but the way it
folds when it falls and how it behaves when the corners are released is very
realistic (too slow, but nonetheless realistic- like a slo-mo of it).
news:3c4e36a8@news.povray.org...
> Algorithmically not very different, but used in another context.
>
> I hope you like it, and I'll be glad to receive your comments and
> suggestions.
>
> Mexico City.
>
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From: Fernando González del Cueto
Subject: Re: Transparent variations on a cloth theme MPG1
Date: 24 Jan 2002 21:59:03
Message: <3c50c9f7@news.povray.org>
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Thank you! I'm glad you liked it!
I'm right now working on an entirely different algorithm, to avoid all these
problems, but it is somewhat complicated, so I don't know if I will able to
implement it correctly.
Thanks again,
Fernando.
"Mahalis" <don### [at] fakey com> wrote in message
news:3c50a0b3$1@news.povray.org...
> These cloth animations of yours are truly amazing!
> This one, as many others have said, is a tad too stretchy, but the way it
> folds when it falls and how it behaves when the corners are released is
very
> realistic (too slow, but nonetheless realistic- like a slo-mo of it).
>
> news:3c4e36a8@news.povray.org...
> > Algorithmically not very different, but used in another context.
> >
> > I hope you like it, and I'll be glad to receive your comments and
> > suggestions.
> >
> > Mexico City.
> >
>
>
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From: Chaps
Subject: Re: Transparent variations on a cloth theme MPG1
Date: 25 Jan 2002 07:21:39
Message: <3c514dd3@news.povray.org>
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I do the same, but i need to change time step each time I change the
"accuracy" of the mesh, and I don't like tries and error algorithm :o(.
I've been driven to a site where there are some studies about cloth
stability with large step calculus, but I did not succeed to get something
out of this stuff yet.( http://www-2.cs.cmu.edu/~baraff/papers/).
Chaps.
news:3c503d0f@news.povray.org...
>
> "Chaps" <cha### [at] yahoocom> wrote in message
> news:3c5009ef@news.povray.org...
> > I like it very much.
> >
> > I am trying, from time to time, to build an external tool wich could
> > generate clothes as mesh2 files from a pov scene, but I have to fight
with
> > instability. do you? how do you handle it?
> >
> > Chaps.
>
> Hi Chaps. I'm still trying to have a more robust algorithm, but meanwhile,
> my only solution is to take smaller time steps.
>
> Fernando.
>
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From: Fernando González del Cueto
Subject: Re: Transparent variations on a cloth theme MPG1
Date: 25 Jan 2002 11:32:04
Message: <3c518884@news.povray.org>
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"Chaps" <cha### [at] yahoocom> wrote in message
news:3c514dd3@news.povray.org...
> I do the same, but i need to change time step each time I change the
> "accuracy" of the mesh, and I don't like tries and error algorithm :o(.
>
> I've been driven to a site where there are some studies about cloth
> stability with large step calculus, but I did not succeed to get something
> out of this stuff yet.( http://www-2.cs.cmu.edu/~baraff/papers/).
Hi Chaps!
What a coincidence! I spent nearly all day yesterday to try to understand
that document. Actually I did understand most of it, but I got badly stuck
with the C(x) condition vector... I believe there must be some errors, or at
least it is not very well explained, because in the Stretch Forces section
(4.2), C(x) is defined as a 2-dimensional vector:
C(x) = a (|wu(x)| - bu , |wv(x)| - bv )
However, in the shear and bend forces section (4.3), C(x) is defined as
C(x) = a * wu(x)^T * wv(x)
Which, I believe it is 1-dimensional, that is, a scalar.
And then, in the Forces and Force Derivatives section (4.1) it says that the
force can be computed like this:
f_i = -k dC(x)/dx_i * C(x)
But f_i is a 3-dimensional vector, so I believe there must be an error
because there is no dimensional agreement. I may be wrong, but I'm stuck.
Did you have the same problem?
Fernando.
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On Fri, 25 Jan 2002 13:21:46 +0100, "Chaps" <cha### [at] yahoocom> wrote:
>I've been driven to a site where there are some studies about cloth
>stability with large step calculus, but I did not succeed to get something
>out of this stuff yet.( http://www-2.cs.cmu.edu/~baraff/papers/).
Regarding cloths, you can find more of David Baraff & Andrew Wittkin's
papers and course notes online. They are the guys that are behind
Pixar's cloth simulation engine. Xavier Provot is also a
well-recognized name in the field. I believe Demetri Terzopolous has
recently been focusing on cloths rather than solids and he has some
interesting ideas like using dynamic NURBS (D-NURBS), or neural
networks, or state-space theory to simulate elastic dynamics.
Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG e-mail : pet### [at] tagpovrayorg
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Well! What can I say?
Its absolutely fantastic! =)
Congratulations.
Best Regards.
news:3c4e36a8@news.povray.org...
> Algorithmically not very different, but used in another context.
>
> I hope you like it, and I'll be glad to receive your comments and
> suggestions.
>
> Mexico City.
>
Post a reply to this message
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From: Fernando González del Cueto
Subject: Re: Transparent variations on a cloth theme MPG1
Date: 27 Jan 2002 01:35:39
Message: <3c539fbb@news.povray.org>
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Thank you JPGargoyle!
It's nice to know that you liked it!
Fernando.
"JPGargoyle" <jpg### [at] clixpt> wrote in message
news:3c533601$1@news.povray.org...
> Well! What can I say?
> Its absolutely fantastic! =)
> Congratulations.
>
> Best Regards.
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From: Chaps
Subject: Re: Transparent variations on a cloth theme MPG1
Date: 30 Jan 2002 07:01:51
Message: <3c57e0af@news.povray.org>
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I should have some time before end of week, and I'll take a look at that.
May be I'll get illuminated.
Chaps
news:3c518884@news.povray.org...
> Hi Chaps!
>
> What a coincidence! I spent nearly all day yesterday to try to understand
> that document. Actually I did understand most of it, but I got badly stuck
> with the C(x) condition vector... I believe there must be some errors, or
at
> least it is not very well explained, because in the Stretch Forces section
> (4.2), C(x) is defined as a 2-dimensional vector:
>
> C(x) = a (|wu(x)| - bu , |wv(x)| - bv )
>
> However, in the shear and bend forces section (4.3), C(x) is defined as
>
> C(x) = a * wu(x)^T * wv(x)
>
> Which, I believe it is 1-dimensional, that is, a scalar.
>
> And then, in the Forces and Force Derivatives section (4.1) it says that
the
> force can be computed like this:
>
> f_i = -k dC(x)/dx_i * C(x)
>
> But f_i is a 3-dimensional vector, so I believe there must be an error
> because there is no dimensional agreement. I may be wrong, but I'm stuck.
>
> Did you have the same problem?
>
> Fernando.
>
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