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sand particles jittering about with deforming collider


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hi everyone i have a small issue here with my sand grains (wet grains) - i'm trying to get my mesh to collide with them but they seem to be jumping about a fair bit as the character moves.  I'm not sure what i can do to adjust this jumping about does anyone have any ideas?

playblast below to show you what i mean.  I cant share the scene file right now sorry but the jumping of particles is quite noticeable here


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30 minutes ago, Hokmah said:

try to play a little with friction of this character and ground maybe and see if it is working :)

cheers bud i had a go at that and no luck really it doesn't matter what settings i'm putting those to on the ground and/or the char it still bounces them about

i've since found out i can calm them down by adjusting the pop grain solver max accel value - default 50 i toned it down to 15 - still getting lots of shifting about though sadly as if they're just popping from one spot to another :(  after caching i pull the cache into a new node and I used a blast node or two on the points afterward to remove a good chunk of the annoying erroneous ones that seem to climb up his fingers and arm but still got some twitching and shifting about - could really do with knowing whats causing this as i've been at the sim for 2 days now trying variations :(

anyone got any other alternative routes to try out?  simpler node network perhaps to simulate sand grains ?


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@Shinjipierre - hey funnily enough I found this out yday evening.

I don't know how to do a speed limit on the grains but I toned down the max acceleration and removed volume based collision and used the bullet collision on the object with concave. I also tweaked some scale kinetic and other Params and it worked a treat :D I have a much calmer simulation now that is a bit more wet sand but doesn't have the flying loose grains climbing up him.  I'll get a playblast up a little later :) thanks again for your help!

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27 minutes ago, Shinjipierre said:

Speed limit is just a pop node :)

Another thing that can make grain go crazy is emitting them partly inside the collider, we end up having grains connected on both sides of the collider and it explodes

yep i were getting that initially and had to animate my mesh 'lowering' into the sand at the start lol.  I guess in hindset i could perform some sort of blast based on whether they are inside the volume of the mesh or not but meh.. and besides dont know how ha!

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  • 4 weeks later...
45 minutes ago, ParticleSkull said:

Hey @anthonymcgrath, I have the same problem here but couldn't fix it the way you said (still have to play a bit more with the scale kinectic though)

Have you learned something else about this latelly?



hi Alvaro my main things to twiddle were the static threshold and scale kinetic.  also the max acceleration in the solver tab is set to 50 by default - i dropped this down to about 10-15 for my scene - this seemed to restrain alot of the flying particles.  Attached a super quick scene that i created with the dry sand shelf buttons.  Sorry i dont really know much more mate :/


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1 minute ago, ParticleSkull said:

Great! Thank you very much, I'll try some similar parameters.


hope it works for you - in the scene i did the first thing i did was jump on the max accel setting and tone it right down and i was mostly there lol - if you set it to 50 and hit play you'll see weird 'blocking' of sand grains as they are shifted forward.  If you sped up the anim of the ball you'd see the weird flickering of sand grains too most likely.

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