ParticleEmitter leaving particles in scene after being killed

[kyletcooper]

I'm having an issue using the ParticleEmitter in my endless wave game. As the rounds progress the performance is getting worse and I noticed that in engine.currentScene.entities contains a lot of particles that are never getting removed.

onInitialize() {
	this.addChild(
		new ParticleEmitter({
			radius: 5,
			emitterType: EmitterType.Circle,
			minAngle: Math.PI / 2,
			maxAngle: Math.PI / 2,
			isEmitting: true,
			emitRate: 20,
			opacity: 0.75,
			fadeFlag: true,
			particleLife: 250,
			startSize: Bullet.size,
			endSize: Bullet.size,
			beginColor: Palette.Bullet(),
		})
	);

	this.spawnSubShots();
}

onPostKill(scene: Scene): void {
	const emitter = new ParticleEmitter({
		pos: this.pos,
		radius: 2,

		minSize: 1,
		maxSize: 2,
		startSize: 2,
		endSize: 0,

		minVel: 100,
		maxVel: 200,

		minAngle: toRadians(-270),
		maxAngle: toRadians(0),

		isEmitting: true,
		emitRate: 120,

		particleLife: 30,

		beginColor: Palette.Bullet(),
		endColor: Palette.Powerup(),
	});

	scene.add(emitter);

	scene.engine.clock.schedule(() => {
		emitter.kill();
	}, 100);
}

Here's what I think my code is doing:

1. Impact - My idea is that I create an emitter at the location and then kill it myself after a short delay.
2. Trail - Here I attach an emitter to the bullet so as it moves it leaves particles behind. Again my understanding is that this gets killed/removed whenever the parent bullet does.

Is the ParticleEmitter meant to remove it's particles when it's killed or am I misusing this? I had assumed that the particleLife property was used to have the particles automatically remove themselves after they're finished.

[eonarheim]

Hi @kyletcooper! Apologies on the delay I'm catching up from last week.

I don't see anything that looks wrong in the code. However there was a memory leak in v0.29.3 particles that would definitely contribute to perf degradation, In theory the latest alpha bits have fixed this by correctly pooling particles.

Is the ParticleEmitter meant to remove it's particles when it's killed or am I misusing this? I had assumed that the particleLife property was used to have the particles automatically remove themselves after they're finished.

This is a good question, currently the ParticleEmitter does not remove spawned particles when removed from the scene (perhaps it should, I'll look into making this change). It does look like there is a bug where particles don't clean up properly if their emitter is removed before their life runs out 😱 I'll make an issue and get this fixed ASAP

[eonarheim]

Possible workaround is to not cleanup the emitter right away (delay by max particle life) and set the emit rate to zero