understanding simulation groups
still got problems with understanding simulation groups.
so i tried a very simple setup. 2 similar events with particle sim group set to 1 the other to 2.
a "particle physics" in every event with sim group 1 and 2 activated.
now they move together but wont collide.

Attached Files
.max   tyflow_sim_groups.max (Size: 624 KB / Downloads: 65)
Did you adjust the "affect this event only" settings and such, in the Particle Physics operator?
thats the thing i don't get.
i thought if i use groups, than every particle with this group get effected by particle physics.
but it only works for me if i turn "affect this event only" off.
Groups define the types of particles that will generate collisions. "Affect this event only" on/off defines whether the scope of the potential particle list is limited to those within the event, or all those within the flow.
Ok, I´ll just hijack this thread, because I also don´t feel like I get simulation groups yet...
So I have tow physx events A and B.


A is set to particle group 1
B is set to particle group 2

Result: they don´t interact


A is set to particle group 1
B is set to particle group 1+2

Result: they interact.

So if I later want to test only particles from event b, I can test for group 2, but I have to have event B also in group 1, if I want them to interact with event A...

Just wanna confirm, that I finally got through that logic knot in my brain...
Yep, exactly right. Particles can belong to multiple groups, and that's how you define more complex interactions like in your scenarios.
Ok, that's fine, but what should I do if I want to make interact only particles within different groups?

Ex: 1 with 2 but not 1 with 1. Trying to make it with filter for MatID but can't figure out any workaround.
In the PhysX Shape operator there are settings labeled "only collide with" and then you can choose a group.

So in your case, you'd assign groups 1 and 2 to particle A, and just group 2 to particle B, and then in PhysX Shape you'd say "only collide if group equal to 2". That way particles in group A won't intercollide but still collide with group B.
Thank you! I got it! I'm using Property Test (Neighbors) there is that option too and it works.

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