Hello,

I created a vellum simulation with some soft pillows floating in zero gravity.

I like how they make creases here but now I want a stuffed animal bump into the huddle and push them apart. And so far I haven't found a solution to make the pillows keep that small scale creasing but make them pushable on a large scale.

I used the configure balloon constraints for the pillows, and they are either too stiff to crease or too soft to move as single objects.

Do you know another approach that works better here?

did you try to use different stiffness values for the creases and the rest of the pillows?

i'm not super familiar with vellum but i guess you could just edit the constraints before the solver or you could try using an attribute or group, then call that inside the dopnet in a configure vellum constraints and apply different stiffnesses to the areas

eaniix
did you try to use different stiffness values for the creases and the rest of the pillows?

No, the creases are waving all over the meshes randomly. So I can't specify separate areas for them.

eaniix
i'm not super familiar with vellum but i guess you could just edit the constraints before the solver or you could try using an attribute or group, then call that inside the dopnet in a configure vellum constraints and apply different stiffnesses to the areas

yes, I can edit stiffness, damping_ratio etc before the solver, then it doesn't even cost more time to simulate.

But I suspect I need another constraint type here.. Tetrahedrons might be soft on the surface but stiff inside. But they are very expensive.

Also I wondered: Might it be possible to solve sthis in two steps? Let's say, if I first simulate the large-scale locomotion and use that deforming mesh as an input in a second simulation with weaker constraints. I don't know yet if that is possible with Vellum, does anyone know more about that?

Have you tried splitting your setup into two simulations?
1. Simulate your pillows with the creases you want to retain (treat it like a high res version)
2. Then you can create a low res version and simulate the stuffed animal bumping into it without caring about creases
3. After that you can use a point deform to deform your high-res mesh containing all the nice creases with the low-res mesh reacting to the impact.

Thanks, I needed a few days to test all of the Vellum methods.

MAREYUS
Have you tried splitting your setup into two simulations?
3. After that you can use a point deform to deform your high-res mesh containing all the nice creases with the low-res mesh reacting to the impact.

That's an interesting idea. In my project the creasing pillows are still moving away too much, so I have to adjust the volume creating start velocities. But I will also try using the low res simulation for the second sim with Shape match or Pin to target constraints, so the creases might actually be motivated by the locomotion.