Vellum/POP Grains sim limitation

[Jujumarvelo]

Hey everyone !

I would need your help on a sand simulation that I'm working on. It's a 10m high building which is supposed to crumble as a sand castle.

My first thought was to try to do it with vellum grains, but the issue is that I'm getting limited by the amount of particles that I can have. Indeed, my GPU gets full and I've got the classic Kernel issue error in the console, meaning I just can't simulate my thing. I've tried to disable every OpenCL buttons that I could find on the solver (OpenCL Graph Coloring & OpenCL Neighbor Search) thinking it would just disable the use of the GPU for the sim, eventhough I knew it would make it really slow (at least it would have been computed). But it didn't work.

Then I tried to use POP Grains cause from what I've understood, it's not using any GPU accelerated system. But I've got the same issue, the sim just can't be cooked.

Would you have any suggestion for me ?

 

I'm running this on a Threadripper 3960x and a RTX 3080.

test_10.mp4

[kushaldas]

Optimize as much as you can, by caching the grains source, having the grains fall asleep and only awaken when they're needed. Once you have figured out what the maximum number of particles you can handle on your machine, you can fake in a bit more resolution by using a Point Replicate sop on your cached sim.

[Whatsinaname]

What Kushal says and:

- try splitting it up into layers, if possible. 
- Source your particles more cleverly, you might want to use fewer particles for inner/back walls, etc.

 

 

[Jujumarvelo]

Hey, thank you for your answers guys !

The issue is that I've already done all these solutions and that's why I'm getting stuck ^^'

The source is cached and animated with an infection set-up so it's being activated progressively. I've also tried to simulate it with multiple layers of grains with different pscale each (smaller size on the outside and bigger inside) but it seems that Vellum doesn't like to get different pscales so my sim was kinda explosive ^^'

The best solution I've found for now is to have a thin layer of grains on the outside (around 1m of thickness > 80 millions particles, my pc can't handle more). To be able to have as many particles as that, I had to switch my OpenCL on the CPU instead of the GPU, so my VRAM doesn't get full. The inconvenience of course is that the simulation is waaayyyyyyyy slower...

To get "fake matter" inside the building, I did a RBD sim with smart activation so the pieces are not too big and look more like chunks of sand. Then I import it as a collider for the vellum grains and it gives me a correct result.