"Invalid access to property or key 'global_position' on a base object of type 'null instance'." on mouse position.

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1

Godot Version

4.4.1

Question

Trying to run code to create a knob in a 2D scene, but when attempting to run the scene I get an error on a line attempting to gain the global mouse position. Code looks like this:

extends Node2D

@export var maxDist: int = 100
var following := false

func _ready():
	Input.mouse_mode = Input.MOUSE_MODE_VISIBLE

func _physics_process(_delta: float):
	var mouseDistance :=  get_global_mouse_position().distance_squared_to($knob.global_position)
	if mouseDistance < maxDist and Input.is_action_just_pressed("click"):
		following = true
	if Input.is_action_just_released("click"):
		following = false
	print(following)

I thought a line of Input.mouse_mode = Input.MOUSE_MODE_CAPTURED was causing an error but the error persited after commenting the line in question, any clue what is causing this?

2

Based on the code provided, you don’t reference $knob anywhere in your code. You should first get a reference to it before trying to access it, see:

4

The code is appended to a Node2D “Knob” that has as a child node a 2D marker “knob”, maybe I just don’t understand child nodes that well but I thought since “knob” is a child of “Knob” that it would be callable via code?

5

It should work.
Can you share the error you’re getting?

EDIT: oh sorry, didn’t realize it was in the thread title.
Then, try to export the knob as a Node2D variable and reference it manually instead of getting it using the $ sign. I don’t see why it would work better, but it’s worth a try!

6

You need to first reference the node you are trying to use. The best way would be to do it in a similar way you did with maxDist.

@export var knob: Knob

Then you should do:

knob.global_position

Without the $ character.

This also assumes that “knob” has the class_name of “Knob” but if it’s different, use that.
If it’s just a simple Node2D, then do:

@export var knob: Node2D

After you do this, make sure that you set the reference inside the editor like you would with maxDist you already did.