I'm playing around with some of my Mardini entries to fix stuff that I didn't have time for in the one day time frame.

One of them has a patch of dirt (vellum grain) that a plant breaks through. I'm trying to art direct the clumping behavior, but it's very slow. I have about 1.5 million points. Right now I'm doing this:

1. Start the sim about 30 frames "early" to let the dirt settle into its rest position.
2. The plant starts moving up, breaking the surface.
3. Need about 30 more frames after that to see how the clumping is doing.

It's taking 30-60 seconds per frame here so it's a lot of waiting. I did set the areas not affected by the plant to sleep after they settle, which helped. Still, it's all pretty slow.

Any pro tips for how to work more efficiently here? Thank you!

That's a lot of grains potentially.
I tend to use point replicate after the sim, to create the mass, as things like dirt chunks aren't like
grains of sand, you can be more coarse in your resolution, to a point. What are your substeps and iterations?
What GPU do you have?


Cheers

Lewie

you can also potentially sim the settle once, cache that frame and plug into another sim as a source geo

Thanks guys! My substeps are only 1 for now. I saw warnings about that with vellum but it seems to be behaving fine. GPU's are 1060 and 1070 Ti.

Tomas, I did try that method, caching the settled sim, but it really freaked out when I started the new sim from it. Particles flying all over the place. Perhaps it needs more substeps in that case?

Did you remove vel? If it's still present, when you kick it off it will want to move.

tinyhawkus
Did you remove vel? If it's still present, when you kick it off it will want to move.

Thanks, just tried that, but it still bounces upon starting up again. Save settled sim A and then first frame of new sim B moves up. It's the same collider on both, but it feels like when the new sim starts it's like it's overlapping something and trying to fix itself? Not sure.

Here's a very pared down HIP showing the problem. I'm sure I'm missing something simple, but I tried a bunch of stuff and I don't understand why it's not working. Settled sim cached out, new sim started up with attributes reset and it explodes higher upon starting.

Possibly due to the doubling up of vellum grain constraint creation? If I plug the first settled result directly into the second vellum solver it behaves after an initial few frames of settling. Not sure if it's necessary to feed in the constraints between solvers as they're already defined, but at least this doesn't explode.

Arvan
Possibly due to the doubling up of vellum grain constraint creation? If I plug the first settled result directly into the second vellum solver it behaves after an initial few frames of settling. Not sure if it's necessary to feed in the constraints between solvers as they're already defined, but at least this doesn't explode.

Oh sweet, that works great. Somehow I got the idea that it needed to have a fresh grain constraint for the cached file.

No problem, I had the same thought as well - I was thinking of them purely as points and tinkered with attributes and parameters before I realized I was already looking at defined grain geometry and tried feeding it straight in.

BrianHanke
Oh sweet, that works great. Somehow I got the idea that it needed to have a fresh grain constraint for the cached file.

usually you may want to Vellum Pack geo and constraints, cache that and then Vellum Unpack after, so that the constraints are cached also rather than having those plugged from live stream

tamte

BrianHanke
Oh sweet, that works great. Somehow I got the idea that it needed to have a fresh grain constraint for the cached file.

usually you may want to Vellum Pack geo and constraints, cache that and then Vellum Unpack after, so that the constraints are cached also rather than having those plugged from live stream

Great tip, thanks! I'll do that.

Thanks to all your help, plus a little experimenting, I got a very nice result in the end. Quite happy with the clumping here. I cached the settled particles, put all the unaffected ones to sleep, created a very low res version of the fern geo for collision, and got the sim time down to 5-10 seconds per frame. Much improved!