How can you create a CPU Particle free zone?

I’m working on a project that requires a field of particles with instanced geo that is floating around in space, surrounding the character and foreground environment, without the particles randomly generating at the point of origin or floating into the space of the foreground set elements. The camera is locked in place and the environment is for observation purposes only.

I’ve tried nearly everything I can think of as well as trying as many suggestions that I’ve come across online in the forums. I’m hoping that someone can convince me that controlled collisions are actually possible in UE. I just need a particle free zone at the environment. No particles should emit within this zone and no particles should be able to cross over into the zone.

Basically, the environment I’m working on is for health/science education and it’s a microscopic cell field that I’m trying to emulate. The character is standing on a single cell and I need the surrounding environment to just exist without interfering with the foreground environment and I can’t keep the outer cells from randomly interfering. I’ve tried static mesh collision objects, killZvolumes, setting the min and max values of the particles initial location to be very far away from the origin, and nothing is working as it should. It has to be possible, but if it is possible, it shouldn’t be nearly this difficult to figure out. Seems like what I’m trying to achieve should be very simple.

Thanks in advance for any and all help that can lead to a quality solution to this problem.


Wow this is an old post that no one answered so I hope the info is still useful.

From what I understand you’re basically trying to have it so that the player is standing on this cell that is floating (for all intents and purposes) in space and you want an area where the player camera is that the particle effects can’t enter. Now, if you’re okay with the particles “colliding” with this invisible barrier that’s surrounding the player then it’s easy. If you want the particles to simply cease to exist when they cross into this area, then I don’t know if it’s possible. Since I only know the one method, this is what I’d suggest you do.

Inside your modeling package, create a sphere mesh with a poly count that’s fairly smooth, I’d say around 4K polys (reason for this is to make the particle collisions look smoother. If they don’t need to be smooth, then you can lower the polycount of the sphere to whatever you like). This is going to be our “Bubble” barrier to stop the particles.
Export this to the editor and under the collision complexity set this to use Complex and Simple. This sets it up to use per poly collision. Now apply a completely masked material to it so that it’s invisible in game, but still counts as a collision object. I’ll say here I haven’t tested this myself yet, but it should work that you can stand inside the sphere without issue, but the outside faces will block the particles. If not, you’ll have to shell the sphere which will increase the polycount drastically, but I’m 90% sure you won’t need to. Especially if the player isn’t actually moving.

Then in the collision settings of your particle system(s) you can set up multiple collision types (click on the collision module and then scroll down to collision types) depending on what type of actor you want the particles to collide with. Lets say you want the particles to collide with everything… add 3 elements to the collision types and set them to World Static, World, Dynamic and Physics body. Then the particles will collide with the sphere and won’t be able to reach the area the player is standing. It’ll possibly look pretty cool when they hit the outside of the sphere as they’d fall off at a smooth spread.

Let me know if that fixes your problem.

Actually, I just realized, you can set the collision completion option to “Kill” which would essentially make the particles die when they hit the barrier and “cease to exist” but they wouldn’t be able to collide with anything else in the world if you do this. The only way to get them to react with the world they’re in, but cease to exist when they hit the bubble is if you could specify a separate reaction to the different collision types (sadly I don’t believe this is possible in cascade) at which point you could make the “bubble” into a different collision object than the rest of the world (A vehicle for example - a channel that’s not likely to be used by anything else).