orient particle to specific axis: Page 3

orient particle to specific axis

cybereality

No it makes sense. Process happens when you add a node to the tree. But @DJM is setting the cam variable after adding it to the tree, meaning for the first frame, cam is null and thus crashing. Just try what I said, I think it will work.

cybereality

But, I guess yeah, put some print statements in there and see if the camera is being set at all. Maybe there is another bug happening outside of what I'm seeing in the code.

xyz

I already suggested couple of posts ago setting the cam before adding the decal to the tree, and assumed @DJM changed this in originally posted code. I guess we will have to see the latest code version for further suggestions.

xyz

I was curious about when process() gets called first. Seems it's called after the function that created the instance exits. If a var inside instance is assigned immediately after adding the instance to the scene (in the same function) it'll be there when process() is called for the first time. So the problem is - elsewhere. Just as an example. In instanced scene:

func _ready():
	print("instance - ready")
func _process(delta):
	print("instance - process")

In the main scene:

var i = scene.instance()
print("main  - before adding to tree")
add_child(i)
print("main - after adding to tree")

The output is: main - before adding to tree instance - ready main - after adding to tree instance - process instance - process instance - process

cybereality

Interesting. Also, print statements are not flushed immediately. So if your program crashes soon after a print statement, it may not appear on screen. I'm having trouble reproducing it now, but I have seen cases where code after a print crashes, but the print is not displayed. So I wouldn't rely on that, best to use the debugger in those situations.

DJM

i gave up , im waisting too much time on this i used a more simpler spritesheet that doesnt needed to be a stretched billboard. is there a way to request a feature for future godot releases? i dont know what will be changed in godot4 particle system but being able to set a stretched billboard would be great for effects

cybereality

Well that is the thing with Godot. It is very powerful, but not everything comes included. However, it has all the pieces necessary, you just might need to roll up your sleeves a bit. Godot 4.0 is getting a LOT more features, especially for the particle system, so I would not be surprised if this works. However, it may be many months before it is stable, so it might be best to try to make due with the current version.

DJM

i can live with my current solution the main things that are holding me back right now are the import system and the fps camera rendering setup

xyz

@DJM said: i gave up , im waisting too much time on this

Why? Null reference errors are easiest bugs to fix. And they are the most common. It's good to train yourself to get the upper hand on them. You just need to follow the execution flow that ended up in the null reference. Insert as many print statements as necessary every step of the way. You also have a good debugger at your disposal. It will show you a call stack when an exception happens (or on planted breakpoints), so you can clearly see what sequence of function calls brought the code to the crashing point. Debugger also displays variable values in tooltips when mouse is hovered over a variable name.

On a bigger size project like fps, the above should be your standard approach.

I could send you my example but you'll need to adapt it to your setup, which would again result in same or similar errors, as your errors are not billboarding related, but simply the matter of node paths and order of execution, all generic scene management stuff.

So I'd say bite the bullet and squish this bug! :)

Megalomaniak

@xyz said:

@DJM said: i gave up , im waisting too much time on this

Why? Null reference errors are easiest bugs to fix. And they are the most common. It's good to train yourself to get the upper hand on them. You just need to follow the execution flow that ended up in the null reference. Insert as many print statements as necessary every step of the way. You also have a good debugger at your disposal. It will show you a call stack when an exception happens (or on planted breakpoints), so you can clearly see what sequence of function calls brought the code to the crashing point. Debugger also displays variable values in tooltips when mouse is hovered over a variable name.

This makes me think it might be good to have a tutorial oriented at beginner/non-programmers on how to debug their code and what the debugger features available to them even are...

edit: I did manage to find this video from 2020 tho.

DJM

@Megalomaniak said:

@xyz said:

@DJM said: i gave up , im waisting too much time on this

Why? Null reference errors are easiest bugs to fix. And they are the most common. It's good to train yourself to get the upper hand on them. You just need to follow the execution flow that ended up in the null reference. Insert as many print statements as necessary every step of the way. You also have a good debugger at your disposal. It will show you a call stack when an exception happens (or on planted breakpoints), so you can clearly see what sequence of function calls brought the code to the crashing point. Debugger also displays variable values in tooltips when mouse is hovered over a variable name.

This makes me think it might be good to have a tutorial oriented at beginner/non-programmers on how to debug their code and what the debugger features available to them even are...

edit: I did manage to find this video from 2020 tho.

yeah im not really a good coder ;)

DJM

ive managed to get the error dissapear, i simply added an if cam!= null

now the game runs again i think i probably had an instance allready in my scene that i overlooked. now the code runs fine however i dont see the particle heres my current decalscript>

extends Spatial



export (AudioStreamSample) var impactsound 
export(NodePath) var particles1_path
export(NodePath) var particlesStretched_path
export(NodePath) var myaudio_path
onready var particles1 = get_node(particles1_path)
onready var particlesStretched = get_node(particlesStretched_path)
onready var myAudio = get_node(myaudio_path)
var cam = null

var random = RandomNumberGenerator.new()

func _ready():
	
	#add_to_group("ignore")
	random.randomize()
	addDecal()

func addDecal():
	myAudio.stream = impactsound
	myAudio.pitch_scale = random.randf_range(0.9, 1.1)
	if myAudio.playing  == false:
		myAudio.play()
	particles1.set_one_shot(true)
	particles1.set_emitting(true)
	particlesStretched.set_one_shot(true)
	particlesStretched.set_emitting(true)
func _process(delta):
	# check if cameranode isnull!
	
	if cam !=null:
		var lookat = cam.global_transform.basis.z.normalized()
		# set look direction to shader
		particlesStretched.process_material.set_shader_param("lookat", lookat )
		
		
	
	
	# assuming the forward direction is our current local z axis, send it to shader
	var hitNormal = global_transform.basis.z.normalized()
	particlesStretched.process_material.set_shader_param("hitNormal", hitNormal)


func _on_VisibilityNotifier_camera_exited(camera):
	self.queue_free()

cybereality

Basically exactly what I said.

DJM

@cybereality said: Basically exactly what I said.

yup

xyz

@DJM said: ive managed to get the error dissapear, i simply added an if cam!= null

That's in fact not a good idea in this situation. Since decal depends on having this variable set and cannot function without it, you actually want code to crash if this is null, not silently go over it. It's ok for certain cases but not when you're debugging. Your sprite doesn't show and now you don't know whether it's because of cam==null or something else entirely. Let the null reference crash the program and ensure that decal is always properly initialized so this can never happen.

I made you a fully functioning demo. My initial shader code was a bit dodgy as it didn't calculate per-particle lookat. Instead of camera basis.z, shader now takes camera position and calculates per-particle lookat. Everything else is the same.

Considering how much time I've spent so far on this, I'll get very angry if I don't see these decals in the finished game ;)

DJM

@xyz much appreciated, please dont get mad ;) your project works perfect , ive adjusted my code ,now i can see the particles but they always go to the right of where im looking at maincam prints the correct value

heres my raycastscript>

extends RayCast

export(PackedScene) var impact_normal
export var force = 20.0
export var damage = 50.0
export (NodePath) var maincamera_path
onready var maincam = get_node(maincamera_path)


func firebullet():
	self.force_raycast_update()
	#print(maincam.name)
	if self.is_colliding():
		var collider = self.get_collider()
		var impact = impact_normal.instance()
		
		
		var n = self.get_collision_normal()
		var p = self.get_collision_point()
		
		collider.add_child(impact)
		impact.global_transform.origin = p
		impact.forward = n
		impact.cam = maincam
		impact.look_at(p+ -n,Vector3.UP)
		
		
		if collider is RigidBody:
			
			collider.apply_impulse( p - collider.transform.origin ,- self.global_transform.basis.z * force)

and the decalscript>

extends Spatial

export (AudioStreamSample) var impactsound 
export(NodePath) var particles1_path
export(NodePath) var particlesStretched_path
export(NodePath) var myaudio_path
export(NodePath) var decalprojector_path
export var stretchedparticleScale : Vector2 
export var decalmaxSize = 0.1
export var decalminSize = 0.05
onready var decalprojector = get_node(decalprojector_path)
onready var particles1 = get_node(particles1_path)
onready var particlesStretched = get_node(particlesStretched_path)
onready var myAudio = get_node(myaudio_path)
var cam = null
var forward: Vector3

var random = RandomNumberGenerator.new()

func _ready():
	
	add_to_group("ignore")
	random.randomize()
	var randomscale = random.randf_range(decalminSize, decalmaxSize)
	decalprojector.scale = Vector3(randomscale,randomscale,randomscale)
	addDecal()

func addDecal():
	myAudio.stream = impactsound
	myAudio.pitch_scale = random.randf_range(0.9, 1.1)
	if myAudio.playing  == false:
		myAudio.play()
	particles1.set_one_shot(true)
	particles1.set_emitting(true)
	particlesStretched.set_one_shot(true)
	particlesStretched.set_emitting(true)
func _process(delta):
	particlesStretched.process_material.set_shader_param("campos", cam.global_transform.origin)
	particlesStretched.process_material.set_shader_param("forward", forward)
	particlesStretched.process_material.set_shader_param("decalScale", stretchedparticleScale)
	
	

func _on_VisibilityNotifier_camera_exited(_camera):
	self.queue_free()

DJM

i dont see how u allign the instance to the impact normal in your code. the arrow points correctly in your project.

xyz

Is your collider moving/rotating?

DJM

@xyz said: Is your collider moving/rotating?

xyz

Umm... there should be a look_at() call somewhere. Anyway, here's a version that operates in local space so it properly handles decals attached to moving objects. In the below demo both - the camera and the object - are moving. Make sure your particle node emits in local space (Particles.local_coords) and that particle shader's Local to Scene flag is enabled (Resource.resource_local_to_scene)

« Previous Page Next Page »