Hello, I have a particle simulation (pop grains) and want to optimize it because I'll need a lot of particles. These particles are essentially falling down and piling up.

In a SOP Solver within the DOP I make a VDB out of particles that are deep within the pile and delete those particles as they wouldn't really affect the sim anymore anyway. This works, but now how do I use this VDB as a collider? The idea would be to take the previous frame's VDB collider, VDB combine the two and set this new VDB as the current collider.

The attachment contains a sketch of the setup. Thank you!

I've got it working now. I had to connect things a bit differently, then I was able to get everything into the SOP solver. Inside, I can differentiate between the collision geo and the particles, deleting the particles and growing the collision geo over time.

I could not do this with a static object, any changes I tried to make in a SOP Solver were simply ignored. They are also ignored if the RBD object is not set to Create Active Object. The problem with it on active is that it reacts to the particles pushing against it, so I had to give it extremely high mass.

It seems to be working as intended, the only thing missing is volume collisions. The RBD object is using surface collisions right now because I have not yet figured out how to get volume colliders into the SOP solver. Its Data Name is Geometry, and that only gets me the polygonal surface. Using Geometry/Volume sometimes works but produces crashes, I'm probably not doing it quite right.