Inflatable structure with Kangaroo

I`d like to create a inflatable structure with Kangaroo, which is “trapped” inside a cage and is pushing through the open spaces.

As a collision object (the cage) I used a box and Multipipe to get a volume out of the wireframe. Inside the cage are 8 different mesh spheres, which should inflate and also collide with each other.

The collision between the spheres is working good but the spheres are pushing through the cage at a certain point.
And I dont know what Im doing wrong.

Kangaroo (15.1 KB)

Hi @kevin.huegle18 , have a look at the definition I posted in this thread


For a better collision with the Multipipe object, divide the curve segments…

I would use TriRemesh on your mesh spheres. It leads to a nicer result.

And I don’t see a benefit of using the bouncy solver.

Kangaroo (30.7 KB)


@martinsiegrist @DanielPiker

Thank you !! This helped a lot

If I increase the target volume before starting the simulation, the same problem reappears at some point. If I change them during the simulation, it works much better.
So start the simulation with a low target value and than increase it slowly.

Is there a parameter I could change to avoid this?

You have the right approach increasing the target volume slowly.
If there is a big instantaneous difference at the start between the initial volume and target volume, it can cause parts to move so fast in one iteration that it misses a collision.

Another alternative might be to combine this with the the edge collision goal I shared here

It would probably be slower than just checking the vertices for collision with the frame, but less prone to passing through it.

This one clarification just changed everything for me lol
thanks :slight_smile: