Make Particles emit a signal when all particles finished

[Anyeos]

Describe the project you are working on:
A simple shoot em game with explosions.

Describe the problem or limitation you are having in your project:
It is unelegant when you make an explosion or some other effects write a lot of code to only call queue_free().

Describe the feature / enhancement and how it helps to overcome the problem or limitation:
If I have a signal for the Particles2D and Particles in general when it stop emitting, I can attach a function to it and call directly queue_free() when it finish. Or make more complex effects like spawning another particle.

Describe how your proposal will work, with code, pseudocode, mockups, and/or diagrams:

func _on_Particles2D_finished():
  queue_free()

If this enhancement will not be used often, can it be worked around with a few lines of script?:

extends Node2D

var lifetime

func _ready():
	lifetime = $Explosion.lifetime
	$Explosion.emitting = true

func _process(delta):
	lifetime -= delta
	if lifetime < 0:
		queue_free()

Is there a reason why this should be core and not an add-on in the asset library?:
Because it is easy to implement signals like the ones of AnimatedSprite

[WippingPost]

Hello!
New to Godot, and I found this post since I too have been wondering how to remove my Particles2D object when the its emitting is done. When using "One Shot" the objects "emitting" property will automatically reset itself to "false", so checking for:
Prticles2d.get("emitting") = false in func _process(delta) would be better especially when using a randomness parameter for lifetime. That is what I found worked best for me.

[macmv]

Checking particles.emitting every frame is annoying and makes ugly code. The current solution I can think of is using a Timer, and connecting the finished signal of that. But this means that you would need to start a timer when you started the particle. This is annoying, but the cleanest solution I can think of. You could also add the particle to the parent scene, and then call queue_free() immediately. But this requires that you make sure to remove the particles after they are done playing, which brings us back to the initial problem.

[WippingPost]

Hello! I agree that checking get("emitting") every frame is not optimal, but... Using a timer is fine I guess, but when using random lifetime you're only guessing when it's done. And if you change the setting of your particles2d you have to change the timer too. I guess you could set the timer to way off to be sure it's done and that would be fine since the particles will be running on the gpu mostly. Timer or not...in the background there still will be checking every frame (we just don't see it in our code) so for me, the best option is to signal when when the emitting is actually done. Den ons 9 dec. 2020 21:39macmv <notifications@github.com> skrev:

…

Checking particles.emitting every frame is annoying and makes ugly code. The current solution I can think of is using a Timer, and connecting the finished signal of that. But this means that you would need to start a timer when you started the particle. This is annoying, but the cleanest solution I can think of. You could also add the particle to the parent scene, and then call queue_free() immediately. But this requires that you make sure to remove the particles after they are done playing, which brings us back to the initial problem. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#649 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ALDCBK3AILVHAOAVOYTRRYLST7OANANCNFSM4LWEMXCQ> .

[Xrayez]

See godotengine/godot#7887 where this feature was added, and godotengine/godot@95560e0 where this feature was removed.

It's seems trivial to re-add, but I'm concerned about the usefulness of the current GPU implementation. The problem with things like explosions is that you want all particles to be processed, and not just when particles stop emitting, as it takes remaining particles to fade out as well even if you set emitting = false, so it looks like it takes lifetime * 2 seconds before the node can be freed without remaining particles to suddenly disappear, in fact...

See also my approach at this Q&A answer:

extends Particles2D

func _ready():
	one_shot = true
	emitting = true
	var time = (lifetime * 2) / speed_scale
	get_tree().create_timer(time).connect("timeout", self, "queue_free")

particles_emission_finished.zip

[WippingPost]

I disagree, because "emitting" is only set to false when the last particle is done. Meaning it has run it's course. You can easily check this by tracking the "emitting" property by overriding it's "_process" method. Here's the code for the explosion (and a smoke) particles I use in a game. Of course you can set a timer to que_free(), but when you are using randomness for the particles lifetime, I have found this way to work best. Otherwise you would be guessing when it's done emitting. extends Node2D var fire var smoke *func _ready():* fire = get_node("Fire") fire.set("one_shot", true) fire.set("emitting", false) smoke = get_node("Smoke") smoke.set("one_shot", true) smoke.set("emitting", false) start() *func start():* fire.set("emitting", true) smoke.set("emitting", true) *func _physics_process(delta):* # Removing object from memory when particles emitting is finished if !fire.get("emitting") and !smoke.get("emitting"): queue_free() Den tis 19 jan. 2021 kl 19:42 skrev Andrii Doroshenko < notifications@github.com>:

…

See godotengine/godot#7887 <godotengine/godot#7887> where this feature was added, and ***@***.*** <godotengine/godot@95560e0> where this feature was removed. It's seems trivial to re-add, but I'm concerned about the usefulness of the current GPU implementation. The problem with things like explosions is that you want *all* particles to be processed, and not just when particles stop *emitting*, as it takes remaining particles to fade out as well even if you set emitting = false, so it looks like it takes lifetime * 2 seconds before the node can be freed without remaining particles to suddenly disappear, in fact... See also my approach at this Q&A answer <https://godotengine.org/qa/92493/gpu-particles-2d-emit-only-when-visible?show=92673#a92673> : extends Particles2D func _ready(): one_shot = true emitting = true var time = (lifetime * 2) / speed_scale get_tree().create_timer(time).connect("timeout", self, "queue_free") particles_emission_finished.zip <https://github.com/godotengine/godot-proposals/files/5837924/particles_emission_finished.zip> — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#649 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ALDCBK3UL5ZX6YJOF54E4ELS2XHCFANCNFSM4LWEMXCQ> .

[Xrayez]

I disagree, because "emitting" is only set to false when the last particle is done. Meaning it has run it's course.

Well I think we certainly have a misunderstanding here... I think it depends on how fast your particles process, so you might not necessarily see the difference.

Here's what I mean by "not emitting", notice how particles still process.

godot_particles_emitting_stop.mp4

extends Particles2D

func _ready():
	one_shot = true
	emitting = true


func _physics_process(_delta):
	if not emitting:
		$debug.text = "Not emitting"
	else:
		$debug.text = "Emitting"

If you were to queue_free() the node whenever emitting property is set to false, then all those remaining particles will suddenly disappear, which is not desired. Therefore, I think using the lifetime (and checking emitting property), may produce the desired result.

See test project:

particles_emission_finished.zip

Of course you can set a timer to que_free(), but when you are using randomness for the particles lifetime, I have found this way to work best.

I think it's still possible to calculate the maximum lifetime regardless, but yeah as I said, both techniques can be used to workaround this in the best way possible.

Therefore, what I'd find useful is particles_processed signal of some sort, rather than emission_finished for this use case (both signals have valid use cases tbh).

[WippingPost]

Ok. I get your point, but that's wierd since I did the same test when creating my particles, checking to see that they really are finished. Are you using randomness of the lifetime of the particles. Good presentation though! 👍 Den tis 19 jan. 2021 21:26Andrii Doroshenko <notifications@github.com> skrev:

…

I disagree, because "emitting" is only set to false when the last particle is done. Meaning it has run it's course. Well I think we certainly have a misunderstanding here... I think it depends on how fast your particles process, so you might not necessarily see the difference. Here's what I mean by "not emitting", notice how particles still process. https://user-images.githubusercontent.com/17108460/105087794-b4895400-5aa3-11eb-8826-ec4491284b4f.mp4 extends Particles2D func _ready(): one_shot = true emitting = true func _physics_process(_delta): if not emitting: $debug.text = "Not emitting" else: $debug.text = "Emitting" If you were to queue_free() the node whenever emitting property is set to false, then all those remaining particles will suddenly disappear, which is not desired. Therefore, I think using the lifetime (and checking emitting property), may produce the desired result. See test project: particles_emission_finished.zip <https://github.com/godotengine/godot-proposals/files/5838386/particles_emission_finished.zip> Of course you can set a timer to que_free(), but when you are using randomness for the particles lifetime, I have found this way to work best. I think it's still possible to calculate the maximum lifetime regardless, but yeah as I said, both techniques can be used to workaround this in the best way possible. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#649 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ALDCBKYINJZDHBUXVJZMVADS2XTFVANCNFSM4LWEMXCQ> .

[Xrayez]

Apart from modifying gravity, direction, and velocity, no, I haven't touched random-related properties.

that's wierd since I did the same test when creating my particles

May be due to different version of Godot (tested in 3.2.4), or perhaps you've used CPUParticles2D which are different in implementation.

[WippingPost]

I'm not using cpuParticles. I am however using version 3.2.3. Not sure if that has something to do with it. I literally spent 3 knights trying to figure out how to que_free() ONLY when the emitting was actually done. I would like to believe I did not miss anything, but watching your video I guess I must have...😂. I am however using plenty of randomness in the lifetime of both my particles. Maybe that has something to do with it...? Who knows..maybe we're both right... Cheers Den tis 19 jan. 2021 21:43Andrii Doroshenko <notifications@github.com> skrev:

…

Apart from modifying gravity, direction, and velocity, no, I haven't touched random-related properties. that's wierd since I did the same test when creating my particles May be due to different version of Godot (tested in 3.2.4), or perhaps you've used CPUParticles2D which are different in implementation. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#649 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ALDCBK6VQPQU7I35G4VXFCTS2XVI3ANCNFSM4LWEMXCQ> .

[sairam4123]

I'm currently struggling with this, I find the mixture of checking the emitting as well as lifetime working a little worse for me, sometimes the particles just disappears. I got a slow PC, might be because of that?

[WippingPost]

Hello! Hard to say what is causing your issue, but unless your computer is ancient, I don't think that is the issue. Is there a reason you have to check the emitting? I found that when using randomness in the lifetime of the particles, the best way was to check for "emitting" = true. It's probably not the most efficient way to do it. Den tis 27 apr. 2021 kl 12:32 skrev Sairam Kumar ***@***.***>:

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I'm currently struggling with this, I find the mixture of checking the emitting as well as lifetime working a little worse for me, sometimes the particles just disappears. I got a slow PC, might be because of that? — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#649 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ALDCBK2ZB7PDKZZLADU2AZLTK2HFPANCNFSM4LWEMXCQ> .