How to let Body1 move to Body2?

Container

Hello dear community,

how can I make a KinematicBody move to another KinematicBody?

TwistedTwigleg

I think you have to manually program KinematicBody to KinematicBody collision, since KinematicBody nodes are designed to be code-driven. This answer on the Godot QA has some code that might help (I only glanced through it).

Container

@TwistedTwigleg said: I think you have to manually program KinematicBody to KinematicBody collision, since KinematicBody nodes are designed to be code-driven. This answer on the Godot QA has some code that might help (I only glanced through it).

But that is for pushing, not following.

TwistedTwigleg

Oh, well in that case you can probably just get the direction from body 1 to body 2, and then pass that to the move_and_slide function. Something like this (untested and written in a hurry):

const FOLLOW_SPEED = 10;

func _physics_process(delta):
	# We'll assume a variable called "target" contains a
	# reference to the node the KinematicBody is supposed
	# to follow
	var direction_to_target = global_transform.origin.direction_to(target.global_transform.origin)
	
	# Move to the target using move_and_slide
	move_and_slide(direction_to_target * FOLLOW_SPEED * delta, Vector3.UP)

Container

Parser Error: The identifier "target" isn't declared in the current scope.> @TwistedTwigleg said:

Oh, well in that case you can probably just get the direction from body 1 to body 2, and then pass that to the move_and_slide function. Something like this (untested and written in a hurry):
const FOLLOW_SPEED = 10;

func _physics_process(delta):
	# We'll assume a variable called "target" contains a
	# reference to the node the KinematicBody is supposed
	# to follow
	var direction_to_target = global_transform.origin.direction_to(target.global_transform.origin)
	
	# Move to the target using move_and_slide
	move_and_slide(direction_to_target * FOLLOW_SPEED * delta, Vector3.UP)

Parser Error: The identifier "target" isn't declared in the current scope.

DaveTheCoder

You need to create the variable target and set it to the node reference, for example: onready var target: Node = get_node("/root/put path to other KinematicBody here")

Container

@DaveTheCoder said: You need to create the variable target and set it to the node reference, for example: onready var target: Node = get_node("/root/put path to other KinematicBody here")

https://www.mediafire.com/file/a54y17mxtnu9e3a/New_game.zip/file Not working :(

dotted

I think you are going to need to understand programming a bit more to take advantage of the help you being offered.

If you simply copy pasted the above code, then it will not work because the node path must be the path to the other kinematic body. You will need to get the actual path to that node that will be your target. To do this you will need to at least read the godot documentation on Node and use the get_path() function for the information you need.

DaveTheCoder

I downloaded your project, and got it to work.

The problem was that KinematicBody2 was a child of KinematicBody, instead of being a child of Spatial.

I changed the Scene tree to:

Spatial .... KinematicBody .... .... MeshInstance .... KinematicBody2 .... .... MeshInstance .... Camera

Then I set MeshInstance >> Transform >> Translation to (0,0,0) for both nodes, and then moved the two KinematicBody's apart.

The "var target" has to be changed: onready var target: KinematicBody = get_node("/root/Spatial/KinematicBody2")

After that it works.

You can attach this script to KinematicBody2 to make it a moving target:

extends KinematicBody

func _physics_process(delta: float) -> void:
	translation += Vector3(-.001, 0.001, 0)

Container

@DaveTheCoder said: I downloaded your project and got it to work.

The problem was that KinematicBody2 was a child of KinematicBody, instead of being a child of Spatial.

I changed the Scene tree to:

Spatial .... KinematicBody .... .... MeshInstance .... KinematicBody2 .... .... MeshInstance .... Camera

Then I set MeshInstance >> Transform >> Translation to (0,0,0) for both nodes, and then moved the two KinematicBody's apart.

The "var target" has to be changed: onready var target: KinematicBody = get_node("/root/Spatial/KinematicBody2")

After that it works.

You can attach this script to KinematicBody2 to make it a moving target:
extends KinematicBody

func _physics_process(delta: float) -> void:
	translation += Vector3(-.001, 0.001, 0)

https://www.mediafire.com/file/zzgbsd4p3bg0vji/New_gamel.zip/file still not working.

DaveTheCoder

Select KinematicBody2 in the Scene dock. In the 3D view, note that the bounding box encloses only that cube.

Now select KinematicBody. See how the bounding box encloses that cube and most of the other cube?

That's why it's not working.

Container

func _physics_process(delta: float) -> void: translation += Vector3(-.001, 0.001, 0)

This code is practically a teleportation, right? So this code does not react to any CollisionShapes. Is there a code with the exact same function that reacts to CollisionShapes?

DaveTheCoder

@Container said: This code is practically a teleportation, right?

Yes. Setting translation was only for making a quick demonstration.

The normal way of moving a KinematicBody is to set its velocity and use that as a parameter to move_and_slide() or move_and_collide(), like in the script for the other KinematicBody.

So this code does not react to any CollisionShapes. Is there a code with the exact same function that reacts to CollisionShapes?

I'm not sure what you mean by "react to any CollisionShapes". If you want it to be "pushed" by the other KinematicBody, it would need to be a RigidBody instead of a KinematicBody. https://docs.godotengine.org/en/stable/tutorials/physics/physics_introduction.html#physics-introduction

Container

@DaveTheCoder said:

I'm not sure what you mean by "react to any CollisionShapes". If you want it to be "pushed" by the other KinematicBody, it would need to be a RigidBody instead of a KinematicBody. https://docs.godotengine.org/en/stable/tutorials/physics/physics_introduction.html#physics-introduction

I meant that the KinematicBody with a subordinate CollisionShape collides with other CollisionShapes.

Megalomaniak

The subordinate CollisionShape should have it's own signals you could use.

Container

@Megalomaniak said: The subordinate CollisionShape should have it's own signals you could use.

What signal?

dotted

Refer to the documentation on CollisionShape. They send signals when bodies (kinematic/rigid/etc) or areas come in contact with it (subject to collision layer mask).

If you haven't ever set the collision mask, the default values will mean everything will trigger body/area entered and exited signals. (In other words it'll just work by default)

I would recommend connecting to a body_entered signal from your player character's kinematic-body's collision shape. In the editor navigate to that node and then switch the inspector panel to "Node" (that's the panel where you can set/change values for a node. there's a tab for 'nodes' next to the properties inspector). The Nodes inspector will list all the signals emitted by a node, select the appropriate one and i think alt-clicking will give you the connection popup menu.

From there, the editor will allow you to specify a node to add a handler function and it will 'wire' it to the signal for you. In your case just add a print statement so you get how it works and when it happens.