How to do multiple CollisionShape2D detection in an Area2D - ( SOLVED )

BingBong

I have an Area2D with several CollisionShape2Ds in it.

The scene basicly a 'trap' for a level, with 2 animations, which one is triggered depends on which trigger (collisionShape2d) has been tripped as the player goes over it.

From what I understand (though cant find in the docs) multiple Area2D collisionshapes are all considered the same collision shape. How do I differentiate between which collision shape has been entered.

I want animation-A to play when collisionShape2d-1 is entered and Animation-B when collisionShape2d-2 is entered.

Zelta

i had that problem with terrain, water, buildings and ships, u know what i mean? u could make in some way:

var zonaShape2d1 var zonaShape2d2

this defines 1 area (u must use signals)

func on_collisionShape2d1_area_entered(area): zonaShape2d1 = true

func on_collisionShape2d1_area_exited(area): zonaShape2d1 = false

and then:

if zonaShape2d1 == true: $animation1.play("sadadsd") else: $animation2.play("dfdfdf")

u can use layers and masks too to set the collisions.

i hope this helps

BingBong

Ok, I can see what your getting at, but as the area_entered signal is built into the Area2D node, its not built into the CollisionShape2D node, adding this signal to the CollisionShape2D so it actually detects/signals something when entered is even more beyond my coding capabilities at the moment.

I can get it to detect something, but using the area_entered signal in the Area2D node, BUT, I then have to add another Area2D node to the player scene for it to detect, as it seems it will only detect another Area2D node. Surely as the player already has a collisionshape that can be used for multiple things?

If I have just one (or two) collisionShape2D node, this works... so simple!

func _on_Trap1_body_entered(body):
	print("u hit trap")
	$AnimatedSprite/AnimationPlayer.play("Triggered")

but deciding which one has been entered is another matter.

Just for reference this is the trap... it flips one way or the other depending on which hair is triggered. In theory.

Any other suggestions anyone?!

Bean_B_Beanie

I'm not sure if you have seen this, but looking at the documentation for the Area2D, I saw it has the signals area_shape_entered and body_shape_entered. Both give the following values:

area_shape_entered: ( int area_id, Area2D area, int area_shape, int self_shape )

body_shape_entered: ( int body_id, Node body, int body_shape, int area_shape )

I'm going to speculate with the area_shape_entered, but it should also apply to body_shape_entered. Based on the (honestly lackluster) descriptions for these two signals, it seems that "area_id" is the instance ID of the Area2D that entered the signal owner. The "area" is the Area2D instance itself; I don't know why they have these two values given by the signal. The "area_shape" is the index of the CollisionShape2D of the invading Area2D shape. The self_shape is the index of the CollisionShape2D of the signal owner.

Say you have two Area2D nodes, one named "A" and the other named "B". A has only one CollisionShape2D as a child; and B has four CollisionShape2D nodes as its children. B also has its signal area_shape_entered connected to some other node's script. A is walking around, and happens to enter B so the two are intersecting, specifically the second CollisionShape2D child of B. B sends out its area_shape_entered signal and the connected function receives the following information:

(1184, [Area2D:1184], 0, 1)

Now, the 1184 and [Area2D:1184] are both temporary placeholders for the sake of this explanation -- these values can and will change during code execution. So, what does this tell you? Well, 1184 is the Instance ID of A; it is given as an integer. [Area2D:1184] is A itself. The 0 is the index of the CollisionShape2D child of A; since A only has one child, which is CollisionShape2D, this value will always be zero. Of course, if there are other children of A, this value may change depending on where the CollisionShape2D is located, so keep that in mind. And finally, the 1 -- this is the index of the CollisionShape2D child of B (hence why it is given the name "self_shape"). Like above, if this CollisionShape2D is anywhere else, its index value will change, so remember that.

The signal body_shape_entered will give similar information, however, instead of A being an Area2D itself, it is a RigidBody2D, KinematicBody2D, or a StaticBody2D (though you shouldn't move Static Bodies willy-nilly).

I hope this was helpful, and that it makes sense.

BingBong

Most definately helpful, and it does make sense. Theres quite a bit there to get my head around though, but I can see how / what I should be doing from your reply.! Thanks.

I'll update here once I get it right!

Yes I did read that from the docs, but as you say, lacklustre. Wasnt sure of the usage of those arguments, thats where the docs start to fall down for me (and other beginners im sure), its a bit like having a dictionary, that shows the pronouciation of words but not the meaning! I hope GDQuest is updating the API pages as well as the rest of the docs.

BingBong

Holy crap that ended up being so easy….. :(

So, for a kinematic body, you need the on_body_shape_entered signal sent to whichever script you need it on, each of the collision shapes have an ID number based on which order they are as children of the Area2D Node.

Area2D - CollisionShape2D1 = ID 0 - CollisionShape2D2 = ID 1 - CollisionShape2D3 = ID 2 etc….

so as the signal is sending an area_shape argument to the function, which is the ID number of the collision object entered, just a simple if statement on the area_shape ID number, and we are in business.

func _on_Trap3_body_shape_entered(body_id, body, body_shape, area_shape):

	if area_shape == 0:
		$AnimatedSprite/AnimationPlayer.play("Triggered3B")
	if area_shape == 2:
		$AnimatedSprite/AnimationPlayer.play("Triggered3A")

Thankyou Bean_B_Beanie, you helped me more than you know, and much more with all that info you gave!