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how can I inflate cloth ?


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  • 4 weeks later...

Here's an example. Even though the stretch stiffness is quite low, it starts to fight back at some point.



Hi eetu, thanks for the example, can you please explain "attribcreate_targetV' in sopsolver , why the calss is set to vertex not point? what is the different in DOP 


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If you look at the geometry data in DOPs (with a spreadsheet or a detail view pane) you can see that the targetv and targetP normally created by the solver are vertex attributes, not point attributes. We want to override those values, so we need to write to vertex attributes.

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I had a really hard time doing some inflating cloth recently. I was trying to remake some old footage from the 60's of Project Echo [a large balloon made of very thin silvery material inflating in space]. What I ended up doing was making a rough animated version in SOPs, then using that as target geometry in DOPs, with some forces and so on.


The main problem I had was that being cloth, it can't really appear to stretch very much, else it would be more like bubblegum or something. So right from the beginning it has to appear that all the geometry is there, creased and folded up which of course isn't really feasible.


I'd be interested to hear your progress with your project.


This was my end result -


And this is a different treatment of the end of the shot...

Edited by j00ey
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  • 1 year later...
  • 2 months later...
  • 1 month later...

For some reason seems like the targetP attribute needs to be a point attribute these days. (Even though the documentation says point or vertex).


Change AutoDopNetwork->sopsolver->attribcreate_targetV->Class from vertex  to point and it starts inflating again. Looks like the stiffnesses have changed in the solvers, so re-tweak.

Edited by eetu
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  • 2 months later...
  • 5 months later...

Hi everyone, I figured out a nice way to suck air out of a piece of cloth, doing the opposite would likely inflate it. I simply advect the point along the gradient of the sdf. If you subtract the volumes of your collision objects from the volume of your cloth object the points will "collide" as in they won't advect into the collision objects. Further, you can calculate the length of the advection and if below a threshold you can tell it not to advect at all, this would avoid wiggle. 

Here's the example of my shrink wrap inspired by more and more, it's not on a cloth sim yet but it works in sops! It's a sphere shrink wrapping around several collision spheres within it.

Let me know if you have any questions! I've been meaning to do this process on a cloth object, if there's interest I'll make it a priority and share something soon!



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  • 3 months later...

Doesn't seem to work in H16. Data in the DOPs seems to be a bit different. Any idea how to make it work?

Edit. Aaa it works after I changed the cloth object to newer one. Settings need some re-tweaking though.

Edited by Terisan
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  • 2 weeks later...
2 hours ago, lemmingsammy said:

Did you get this to work? Im really struggling with this. Im not really one to ask for a scene file but it would really help.

Not sure what the old settings were relative to what these are now, but all I did was swap out the cloth object for the new one, put the stretch stiffness waaaay down, added some 'Target Strength' in the 'Deformation' tab (so targetP does something), and change the class on the attribute create in the sop solver from vertex to point.


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