How can I completely remove wrinkles from a vellum sim?

[TheoK]

Hello,

I am working on a project (can't share the file. I'm sorry) where I am squeezing some spherical objects against a wall.
I am using vellum pressure constraints to simulate it and I am trying to keep the stretching when the squeezing gets too hard, but prevent any wrinkles.
Imagine a bubble that just can't pop, being squeezed extensively against a surface. That's what I'm going for. Lot's of stretching bu no wrinkles.

So far, the stretching is working fine as expected but I am getting wrinkles no matter what.

I tried setting the stretch and bend stiffness to 100e+10, both damping ratios to 0.8, I tried 10 substeps and 3000 constraint iterations on the vellum solver, I even tried using vellum struts and vellum shape match but literally nothing has worked. No matter what I do, I can't get rid of the wrinkles.

What would be your approach to get this effect?

Thank you a lot.

[Drughi]

To help control the wrinkles, you could try running the simulation on a lower-resolution version of your geometry. This often reduces unwanted artifacts like wrinkling. Once you get the desired stretching effect, use a pointdeform to transfer the low-res motion to a higher-resolution mesh. Adding a subdivide as a final step can help smooth out any remaining details and give you that clean, stretched look without wrinkles.

Let me know if that helps!

[Atom]

You could try the vellum brush after the simulation to "iron" out what you don't like.

[jkunz07]

You can also try to reduce the vellum cloth restlength constraint during the sim as the surface becomes compressed to reduce wrinkles.

In a wrangle you could do something like

f@restlength = min(f@restlength, primitiveintrinsic(0, 'measuredperimeter', @primnum);

which will keep the lower value between the existing constraint and the current edge length of the constraint.

[TheoK]

On 11/13/2024 at 4:20 AM, Drughi said:

To help control the wrinkles, you could try running the simulation on a lower-resolution version of your geometry. This often reduces unwanted artifacts like wrinkling. Once you get the desired stretching effect, use a pointdeform to transfer the low-res motion to a higher-resolution mesh. Adding a subdivide as a final step can help smooth out any remaining details and give you that clean, stretched look without wrinkles.

Let me know if that helps!

That's what I ended up doing and it worked like a charm. Thank you!

[TheoK]

On 11/16/2024 at 1:38 PM, jkunz07 said:

You can also try to reduce the vellum cloth restlength constraint during the sim as the surface becomes compressed to reduce wrinkles.

In a wrangle you could do something like

f@restlength = min(f@restlength, primitiveintrinsic(0, 'measuredperimeter', @primnum);

which will keep the lower value between the existing constraint and the current edge length of the constraint.

This is very cool.

Thank you. I will definitely try it!