Hi guys! I need your help again.
I have to make gas explosion fx in UE4.19 (cascade is preferred).
My challenge is make smooth ignition of gas from spark collision point to edge of gas cloud in real time.
For example like this https://www.youtube.com/watch?v=DlV4FmP7me8&feature=youtu.be&t=34
I’m not so good with blueprints, so all my ideas are spawn several actor with gas particle systems and set collision or trigger. When the spark reaches trigger, it run explosion. And this explosion run next nearest trigger and etc. until all trigger get work.
It seems to me- this example use similar logic https://www.reddit.com/r/unrealengine/comments/9nrt0p/poison_fire_explosion/
But it will be not smooth and collision isn’t reliable in that case I think.
What can I do? Any idea?
Thank you a lot for your advice!
The OnParticleCollide works great, Why do you think it isn’t reliable? You only need to fire an event.
Make sure your particles that will do Collisions are on CPU as GPU particles do not store locations etc (too expensive).
Create a BP Actor, Place the particle system in there under your scene root, Make sure inside the particle system that the particles actually collide.
After you’ve confirmed they collide on your BP click on the particle system on the components list and in it’s details scroll all the way to the bottom and click on the event “on particle collide”, Work from there and show us what you’ve done if you get stuck.
edit: forgot to mention, That type of events only work during gameplay as it’s a BP. So play to see if they work.
Thank you, dear @DieByZer0!
I just didn’t know about “Particle collide”. It’s sounds very good, so I will try to do this as soon as it possible and write you immediately about result.
So…Yes, I get stuck 
I turn on Actor collision inside particle system
And add node “OnPrticleCollide”…
but I can’t understand, what it makes, because no one documentation or tutorial are 
And my knowledge about blueprint a bit lack to come up what I can do with it. Maybe you have some example? I have saw one example, how to make a decal into collision point, but my logic with gas is different. I don’t need just explosion in point collision, I need my gas smooth disappear from point of collision with other actor to edge.
The collision isn’t needed on the gas.
The collision should be on the sparks PS.
You do not need that many Max Collisions either. You only need 1.
The Logic, Make a BP that has the gas inside of it as a component, Put a Collision Box to cover the gas area and on another BP Put your sparks as a component and do a check if it overlaps or if it’s collided with that box of the other BP then deactivate the gas and spawn an explosion in it’s place. (Simplified version).
Unfortunately i do not have the time to build that system for you, you will have to open some other blueprints and figure out how they communicate between BPs and such.
I see, Thank you for help!
I will try
