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donQuoique

modeling deforming sponge

I would like to model a sponge which is deformed by the contact with a rigid body. Let's say a sponge in form of box with a solid metal ball pressing it.

What tools (SOPs) can I use?

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For the sponge a good place to start would be with VDBs. You can do VDB subtraction in the vdbcombine node and get some detailed "holey" meshes very quickly.

Once you have an object that you like, you would then use either finite elements or granular solids to get the effect of a soft body.

There's an image to get you started, let me know if you need more details.

Sponge.PNG

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6 minutes ago, Gavin said:

For the sponge a good place to start would be with VDBs. You can do VDB subtraction in the vdbcombine node and get some detailed "holey" meshes very quickly.

Once you have an object that you like, you would then use either finite elements or granular solids to get the effect of a soft body.

There's an image to get you started, let me know if you need more details.

Sponge.PNG

Wow! Thanks a lot! Actually, what I am trying to do is model a sofa with rigid metal frame which hold soft seating cushion. Can I make it with something easier than FEM, for example like "attribute transfer" node?

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If its a one way interaction and your solid metal ball or whatever is being used is stationary or animated then yes.

You could use the metal balls normals along with a blended attribute transfer to deform the points on the couch mesh as the ball gets close. The issue you will run into here is precision as this method will have a tendency to pop.

If you need smooth interaction though I would again use VDB's here as they have the distance to the surface built in and can be filled solid, so you can get better deformations with just some simple math. 

Check out the attached file to see what I mean.

deform_from_object.hipnc

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Thank you very very much! I will check it out when I get back home (as I don't have houdini in my workplace).

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I looked into the network and understood vaguely how it works. But apply this to my model was another thing. Thanks again and I'll post the result if I succeed.

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I somehow succeeded to make the deformation as I wanted (I mean it's close) with attribute transfer and attribute VOP but I think I need more study to make it work with VDB.

I used color (as you did in your model) to blend the normal but how it works is still not quite clear for me although I just happened to make it work. 

Thank you so much again. Your help was enormously useful for me.

sofaKwak.hipnc

 

sofaTest3.jpg

Edited by donQuoique
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