# Particle collision spawn child particles on impact

**URL:** <https://forums.unrealengine.com/t/particle-collision-spawn-child-particles-on-impact/278180>\
**Category:** FX\
**Tags:** particle-collision, unreal-engine, Collision, question\
**Created:** [March 24, 2014, 5:57am UTC](https://forums.unrealengine.com/t/particle-collision-spawn-child-particles-on-impact/278180 "2014-03-24T05:57:40Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![pragmascript](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@pragmascript](https://forums.unrealengine.com/u/pragmascript)\
**Post date:** [March 24, 2014, 5:57am UTC](https://forums.unrealengine.com/t/particle-collision-spawn-child-particles-on-impact/278180/1 "2014-03-24T05:57:40Z")

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Is it possible to create a particle system with collision that spawns additional particles on impact?  
For example rain drops that spawn splashes on the position of the impact with the floor

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**Author:** ![Rama](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/rama/32/882413_2.png) [@Rama](https://forums.unrealengine.com/u/Rama)\
**Post date:** [March 24, 2014, 10:03am UTC](https://forums.unrealengine.com/t/particle-collision-spawn-child-particles-on-impact/278180/2 "2014-03-24T10:03:43Z")

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#Particle Events

**UE4 Wiki Link**

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>
> After over a year in maintenance mode, the official Unreal Engine Wiki is now permanently offline. These resources now live on a new community-run Unreal Engine Community Wiki — ue4community.wiki! You will be able to find content from the official...

Enjoy!

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**Author:** ![\_EPIC\_homeRye](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@\_EPIC\_homeRye](https://forums.unrealengine.com/u/_EPIC_homeRye)\
**Post date:** [March 24, 2014, 2:59pm UTC](https://forums.unrealengine.com/t/particle-collision-spawn-child-particles-on-impact/278180/3 "2014-03-24T14:59:56Z")

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You can use an event generator to do this, the wiki link is a good resource.

I would suggest you consider using the kill box/kill plane, coupled with a death event for spawning your splashes, CPU particle collisions can be expensive on your game thread if you are working on a real-time scene. You can offset your rain spawn locations above the ground, and leave the kill plane at 0.00, then just place your effects on the main ground surface.

If you want to use collision events to drive the splashes, (your ground is not flat etc.) I would recommend mixing GPU and CPU rain particles together to get the occasional splash, and couple this with a material on your surface that mixes a splash effect in. (This is how we handled rain splashes/impacts for Gears3.) Setup a pretty tight LOD for the collision so you are only seeing them when they are close to the camera (i.e. you don’t pay for collisions you cannot see.)

Also, we are in the midst of updating the interface so spawning GPU particles from a CPU particle via a death event does not yield an error message in the interface.

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**Author:** ![pragmascript](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@pragmascript](https://forums.unrealengine.com/u/pragmascript)\
**Post date:** [March 25, 2014, 12:57am UTC](https://forums.unrealengine.com/t/particle-collision-spawn-child-particles-on-impact/278180/4 "2014-03-25T00:57:42Z")

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thanks for your detailed answer 🙂