Hi !
I was experimenting with Niagara and death events when I noticed an unexpected behavior.
I’m using Unreal 5.3.2 but I also tried on Unreal 5.4.4.
I have two emitters, one with the death event and another one with the event handler. The first emitter spawns a finite amount of particles and the second emitter spawn one particle when one particle of the first emitter dies. Nothing fancy.
I noticed that when the last particle of the first emitter dies, the second emitter spawns 2 particles instead of one. And It only happens with the last particle of the first emitter.
Steps to reproduce :
- Create a Single Looping Particle emitter with a spawn rate of 3.
1.1 Properties → Enable Requires Persistent IDs.
1.2 Emitter State → Life Cyle Mode: self, loop behavior: once, Loop duration: 2.
1.3 Particle Spawn → Add Velocity → Set Velocity 50,0,0.
1.4 Particle Update → Generate Death Event. - Duplicate the emitter.
2.1 Emitter State → Loop Behavior: Infinite
2.2 Delete Spawn Rate, Add Velocity and Generate Death Event.
2.3 Add an Event Handler → Set Source to first emitter Death Event.
2.3.1 Execution Mode → Set Execution Mode to Spawned Particles.
2.3.2 Spawn number → Set to 1.
2.4 Add Receive Location Event.
2.5 Particle Update → Add Gravity Force.
Minus the colors, it should look like this
For some reason, when the last particle from the first emitter dies, the death event always spawns the double amount of particles sets in the Event Handler Properties-> Spawn Number.
Am I doing something wrong or is it an issue coming from Niagara ?