"Jim Kress" <dea### [at] kressworkscom> wrote in message
news:3c4f3a29$1@news.povray.org...
> Is this number 1 of 7?
>
> Jim



I'm sorry but I didn't understand your question.

Fernando.

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"Jens Berg Churchill" <jbc### [at] themaxorg> wrote in message
news:3c4e97fd$1@news.povray.org...
> Very nice, the last constrained end stretches a bit far before being
> released but it's not of too much importence.
>
> One thing very few seam to be attempting is tearing, maybe it's on your
> agenda?

Yes, I also think the elasticity is bit exaggerated, but that's why I made
it plastic-like, where this kind of behaviour is allowable.

I also thought a little about the tearing idea, but I realized it wouldn't
be easy at all to implement. My approximate current agenda is:

* rewrite my code in order to optimize it and add some new ideas
* add wind
* try using OpenGL to have a real-time simulation

Thanks for your comments,

Fernando.

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"Apache" <apa### [at] yahoocom> wrote in message
news:3c4ec1a3$1@news.povray.org...
> How do you handle self-collission detection?

I don't! :)

I'm fortunate that it looks like it doesn't cross through itself, but it
does. :/

Fernando.

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> Wow, very nice!
> Imagine what all could be behind it! :-)

Thank you very much, I'm glad you liked it!

Fernando.

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"Mark James Lewin" <m_j### [at] yahoocomau> wrote in message
news:3C4F38D1.7601C583@yahoo.com.au...
> This looks really good! To avoid the fixed points being streched that much
before
> releasing, you could look at the strain they are under, and release them
after a
> certain limit is reached. There would be more consistency in the
simulation then.
>
> How fast are these simulations?
>
> MJL

That's a very good idea! Thanks

Well, the speed depends on how fine you want the mesh, and how small you
make the time steps. Sometimes I take unnecesarily small steps and it takes
ages! And sometimes I'm too optimistic and get overflows at the middle of
the simulation for taking too large steps.

In this particular case, hmmm... I think it took about 2-3 seconds per
frame. Later I have to render each frame, of course!

Thanks for your comments and good suggestion!

Fernando.

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<fcu### [at] yahoocom> wrote:

>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.

It's *way* too elastic, like raw rubber or latex.

Cloth elasticity comes from the fact that it is made of interwoven
threads, be they elastic or not. Tensile forces 'tighten up' the
threads and make the cloth thinner, but the threads themselves don't
elongate, or at least not relevantly much.

The easiest way to model this is to cap strain at some value. The
looser the cloth, the higher the value. It is also much easier to
tweak as the only thing you have to do is measure the tensile strain
of your cloth (at the expense of the sample :) ).

Keep in mind that I haven't actually modelled cloth, only solids, so
though I think I know the theory, I have no experience at it. Trust me
or not at your own risk :)


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

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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.


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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"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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"Peter Popov" <pet### [at] vipbg> wrote in message
news:c9vv4us4j8706qsvtgem59flufjv5qudhc@4ax.com...

> <fcu### [at] yahoocom> wrote:
>
> >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.
>
> It's *way* too elastic, like raw rubber or latex.

Yes, I also think it is too elastic, and that's why I gave it that plastic
texture, so it does not look like a cloth.

> Cloth elasticity comes from the fact that it is made of interwoven
> threads, be they elastic or not. Tensile forces 'tighten up' the
> threads and make the cloth thinner, but the threads themselves don't
> elongate, or at least not relevantly much.

That's right. The threads are very inelastic. But the equations describing
that must be very complicated. You can simplify your model if you ignore the
"tightening" of the threads and compensate with a bit of more elasticity to
the cloth.

I'm now trying to reach an alternative way to solve this, but I still have
to work many hours :)

Thanks for your comments,

Sbogom!

Fernando

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<fcu### [at] yahoocom> wrote:

>That's right. The threads are very inelastic. But the equations describing
>that must be very complicated. You can simplify your model if you ignore the
>"tightening" of the threads and compensate with a bit of more elasticity to
>the cloth.

You can impose a penalty on elasticity if strain goes above a certain
value. Not cap it altogether but penalize it strongly so that the
cloth tends to preserve its original shape without being too elastic.

I would use a strongly non-linear stress-strain relationship if I were
you. Try logarithmic for a start, or exp(-x*t). This way for higher
stresses there'll be almost no increase in strain.

And then you may consider material failure :)


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

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