Beginner Question(s) About Singals and Collision

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Godot Version

Godot Engine v4.2.2.stable.official.15073afe3

Question

Hello, I am new to Godot and I am a bit confused by singals and collision. I hope I can get some help.
My Questions are:

  1. How can i use Signals for Collision and make my Object “solid” so its not entering but colliding
  2. Is this a good way and if not: why and what would you do better? (currently is not colliding but entering the area, but except that)
func spawn(enemyName: String) -> void:
	var enemyScenePath = "res://models/" + enemyName + ".dae"
	ResourceLoader.load_threaded_request(enemyScenePath)

	loadEnemy(enemyScenePath)
func loadEnemy(enemyScenePath: String) -> void:
	var newEnemy_scene = ResourceLoader.load_threaded_get(enemyScenePath)
	var newEnemy = newEnemy_scene.instantiate()
	var thisWorld = $"."#world
	thisWorld.add_child(newEnemy)
	#newEnemy.rotation_degrees = Vector3(0, 70, 0) 
	#newEnemy.scale = Vector3(3,3,3)
	var enemyArea3D = Area3D.new()
	var collisionShape = CollisionShape3D.new()
	var shape = BoxShape3D.new()
	shape.size = newEnemy.scale
	collisionShape.shape = shape
	enemyArea3D.add_child(collisionShape)
	newEnemy.add_child(enemyArea3D)
	enemyArea3D.body_entered.connect(enemyBodyEntered)
	
func enemyBodyEntered(_body: Node3D) -> void:
	print("test")

I know that those questions must seem stupid, but i rly tried to get to a solution on my own with the help of the documentation and at least the code above is working.
Have a great Day.

2

Use RigidBody3D or CharacterBody3D instead of an Area. Area’s don’t “collide” but they can detect physics objects collisions with its collision shape. think of Areas as a proximity sensor.

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3

Thanks, i did it with the Signals of the RigidBody3D but how would i do it with the CharacterBody3D, it does not have any singals in the doc. Do I rly have to use one of the gets for collision, doesnt seem efficent, or am i wrong?

4

Characterbody are a little more complicated but the do have a means for detecting collisions. I don’t know if I can help readily as I have never used one.

And yes you need collisions and collision signals are the best way to get the event. The physics engine is written in C++ so it is also probably as efficient as it could be. There is no other way to detect a collision without physics bodies or a physics engine.

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5

I was thinking about this a little more and was wondering if there was some misconception oh how collisions work.

Basically I wanted to make clear is that you don’t need to worry about handling collisions they will always work.

If you want to know a collision happened, like a weapon hitting an enemy to then deal damage. Collision signals are the best way to get notified of a collision. Yes you may have to deal with other non damaging bodies coming through the signal, but there can be collision layers and masks to optimize this.

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6

I did now implement a working “hitting the enemy”(with RigidBody3D), but the problem that stayed was why does the CharacterBody3D doesnt have Signals and only has those weird gets like

KinematicCollision3D from the get_slide_collision(int slide_idx)

even tho i could make this work with the Characterbody3D now.
The simpel fact that its does not have signals by default is confusing.
I dont understand why i mean it has to have a reason?

Like i can detect collision with those get methods but it feels wrong, but i did it now with the RigidBody3D because it felt more fitting for the purpose but i hope you get where the confusion comes/came from.

7

I haven’t used character bodies, but they let you do all kinds of movement that be really hard to do with force based rigidbody.

I bet there is some signal you could setup, I just haven’t looked at the docs in a while.

I wanted to share something about hitbox and hurtbox design. These are typically built with areas. And for an great example take a look at smash brothers videos that have hacked the game to expose the boxes. After a opponent is hit the force is given to the underlying character body (or rigidbody).

Hitbox - SmashWiki, the Super Smash Bros. wiki.

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CharacterBody3D collisions are detected in the move_and_slide() and move_and_collide() methods, not via signals. They are not controlled by the physics system in the same way as RigidBody3D, but are controlled directly by your code.

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