URGENT Syflex help needed

Discussions about simulation, hair and cloth in SOFTIMAGE©
Pancho
Posts: 659
Joined: 19 Sep 2010, 11:28

URGENT Syflex help needed

Post by Pancho » 26 Jul 2014, 17:02

I need to shrink wrap a rubber glove on a hand. Some initial test with spheres worked, but the actual hand and glove geometry teach me something else.

As the glove needs to be slightly larger in its inital state than the hand (so that it can collide with it and shrink wrap around it) I need a force which actually pulls the glove together, like rubber would do if you strech it. So the initial state is stretched and during the simulation it pulls itself together so that it fits tight on the hand.

But how do I create this force. THe volume force looks o.k., but it actually tries to preserve the surface area of the mesh. It sucks the air out of the mesh, but it doesn't behave like a balloon which would get smaller and smaller the less air it inhabits.

I tried so many things with forces (like a polygon normal force) but always the problem is that I can't shrink the material itself. How would I put together an ICE force which does this? Trying to shrink the material?! Something like a force which tries to pull the neighbors closer. But how could this be done? Or is there another way?

Any help is urgently needed!

Cheers
Thomas

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Mathaeus
Posts: 1761
Joined: 08 Jun 2009, 21:11
Location: Zagreb, Croatia

Re: URGENT Syflex help needed

Post by Mathaeus » 27 Jul 2014, 00:05

There's "mimic" constraint, which forces the simulated mesh to follow the deformed copy. If deformed copy shrinks and distance is more than zero, it creates the wrinkles,also it vibrates around target. At zero distance, it acts like sort of shape key target. So you'll able to override the Syflex's perception of physics.
As far as I know, Syflex volume force tries to keep the distance to opposite side of mesh, looking from normals. I'm afraid , no that much of hope from this force, for even little more complex shape, like gloves.
Your task is very very hard for simulators. I'd say, more plain overrides of 'do it all by simulation' approach, like mentioned mimic constraint - better chance to get something believable.

Pancho
Posts: 659
Joined: 19 Sep 2010, 11:28

Re: URGENT Syflex help needed

Post by Pancho » 27 Jul 2014, 12:08

THanks for your thoughts. I actually tried the mimic force. I used a shrunk glove and mimiced the one which is slightly wider than the hand. But the mimic force (in my opinion) can't be properly changed. I didn't succeed with reducing the force so that the glove shrinks around the hand with collision detection.

This is very troublesome.

But if the mountain isn't coming to the prophet, the prophet, well, you konw the story.

So in the end I shrunk the hand and used a linear interpolate node to reach its original shape within a few frames. This way the glove strtches over the hand and I don't need to tweak any simulation settings. Really cumbersome behaviour of my favourite software.