Simulating fatty tissue and jiggle.

Discussion about softbody / cloth simulation in Realflow 4
zzenn
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Simulating fatty tissue and jiggle.

Postby zzenn » Sun Aug 10, 2008 8:44 am

I got interested in realflow when I saw someone mention it could be used for simulating the jiggle motion of fat. I started investigating, looking at training material and reading the "manual."
Unfortunately I've not found anything that indicates this is possible. It would seem easy for realflow to accept part of a mesh as a softbody, and perhaps deform this part more or less with a weight map.
This way anything from flappy sumo wrestler folds, bear stomachs, heavy buttocks and indeed breasts could be simulated realistically.

Please tell me if I've missed something, of if this is presently impossible.

And if it is possible, please point me in the right direction.

If it's not possible, and if realflow devs are reading this - please try and incorporate this kind of functionality. It would make an already great application truly outstanding. Just think - skin/mesh deformations with 'true' volume. Awesome!


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Ls3D
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Simulating fatty tissue and jiggle.

Postby Ls3D » Sun Aug 10, 2008 2:39 pm

3D applications typically have springs or flex modifiers that can easily address this type of deformation & simple dynamics, combined with soft selection or falloff, this is pretty easy to setup and can calculate in near realtime, VS the hours or days a common RF sims runs.

Visit my YouTube page to see the gigglies as described...

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zzenn
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Simulating fatty tissue and jiggle.

Postby zzenn » Mon Aug 11, 2008 1:52 am

You're correct, and I've seen a lot of very good rigs with that method.

However, springs etc., probably won't work if you try to manipulate the fatty tissue. For example: Let's say you have a fat penguin. Somebody then proceeds to poke the penguin in the belly. How do you simulate the skin bending inwards and then springing back after the poking hand retracts?
With realflow particles inside the volume somehow, that stuff could work.

The time isn't so much an issue for me at this point. I'm more curious if it is actually possible or not with realflow to do this kind of simulation.
I know it can be done with standard realflow primitives. Like, you poke a softbody ball with other geometry. But what I want is to make *parts* of a mesh softbody with volume, like stomach/breasts/buttocks and then simulate whatever interactions may occur.

Btw, I visited your YouTube page. What's the name of the video you recommend watching?

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Ls3D
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Simulating fatty tissue and jiggle.

Postby Ls3D » Mon Aug 11, 2008 3:59 am

For the poke I would use free form deformation lattices, but I can appreciate a little soft body R&D too,.. so setup a soft body and poke it, high dampen values, etc.. remember the power punch from the matrix - there is a great blogish thing on it, that could inspire.

The jigglies are in the Homage to Dali - PG13 clip. Hopefully you will come up with something and return to share your results.

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zzenn
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Simulating fatty tissue and jiggle.

Postby zzenn » Mon Aug 11, 2008 4:59 am

Yes lattices could work. I guess I'm trying to go for the lazy-yet-complicated way :)

As for the softbody approach, that's why I'm posting here, to see if realflow supports this explicitly. As in defining parts of a mesh as softbody, but leaving the rest alone. Weightmap use seems obvious here.

I checked out the Homage clip. Yup, it does jiggle, and it works for the clip. I'm trying to get something that will work on a much larger scale and which will interact with other objects.

Syflex is another option which will automatically deform and revert the mesh, depending on outside interactions. Unfortunately it's verrrry tricky to set up for these kinds of simulations.

Simple stuff, like balls and blobs, is easy. Part of my goal is reaching the point where the 'soft' parts of an otherwise solid mesh are truly soft and will deform as such with environment interaction.

I wish I could come up with something, but first I need to know whether this is something supported by real flow - but perhaps not mentioned in the 'manual.'
A review of RF said it does support fatty jiggle, like on a sumo wrestler, but nowhere have I been able to find documentation to support this claim.
Blindly forging into the application won't do me much good, unless I know what to look for :)

shaun_michael
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Simulating fatty tissue and jiggle.

Postby shaun_michael » Mon Aug 11, 2008 5:42 am

Syflex is another option which will automatically deform and revert the mesh, depending on outside interactions. Unfortunately it's verrrry tricky to set up for these kinds of simulations.

I was also going to mention the cloth sim approach. If I have time I'll see if I can dig up some very nice Lightwave examples (and of course you can look on Syflex's site for some nice examples of how it's been used for the same thing).

Oh, and...

Unfortunately it's verrrry tricky to set up for these kinds of simulations

I dont think Realflow would be any more forgiving either.

Shaun

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Ls3D
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Simulating fatty tissue and jiggle.

Postby Ls3D » Mon Aug 11, 2008 5:51 am

Well I reckon even though RF does gases, I would rather use FumeFX for fire and smoke, and even though RF does softbodies, I would rather have instant feedback and control VS dynamics.

If it is proof of concept you seek HERE is a sphere, partially pinned, a bit of wind & a pokey object... possible yes, practical not IMO.

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bitSeq
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Simulating fatty tissue and jiggle.

Postby bitSeq » Mon Aug 11, 2008 10:25 am

This is an interesting question. Perhaps this could be possible using the soft body approach and fill pockets with water, for example muscles and fatty tissue pockets could be fixed to a skeleton and then in RF these pockets could be filled with liquid?

I might have to experiment with the soft bodies now, cheers.

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ChristianZ
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Simulating fatty tissue and jiggle.

Postby ChristianZ » Mon Aug 11, 2008 2:09 pm

bitSeq wrote: I might have to experiment with the soft bodies now, cheers.

I have always had big problems (crazy lines all over the viewport, then crash), when trying to use 'self collision' in softbodies.
RF10 standard + RFC4D

zzenn
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Simulating fatty tissue and jiggle.

Postby zzenn » Tue Aug 12, 2008 3:09 pm

bitSeq, that's an interesting idea. I'd love to see it in action!

From the responses in this thread, however, I'll conclude that RF does not support what I'm after. It's a *very* useful application with what it does now, but I guess it can't cover everything.

I'll try and look more into softbodies, soft contraints and cloth options.

Btw, I think I have an example somewhere that kinda illustrates what I'm after... err.. but it's definitely not safe for work (boobies), so I don't know if I should post it here. Let me know if I'll be banned for posting a link =)


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