How to read pixels from SubViewport image?

@xyz If it is the sub-menu under the render target for the SubViewport Node it already set like this (and won't work as I want)

xyz That's because I'm instancing this LightDetect packed scene into my Character scene, and the character packed scene is being instanced in my testLevel scene. So I was expecting it would create images using the testLevel scene light.

xyz I tried both ways. I'm not sure I did it correctly. First I tried the RemoteTransform3D node (didn't know this node before) (How do I highlight these names?). I set the Remote Path to the Light Detect (Node 3D parent) and it did not work.

Then I tried the following code on _process() in LightDetect.gd and also got the same result.

extends Node3D

var LightLevel : float

@onready var camera_3d: Camera3D = $SubViewportContainer/SubViewport/Camera3D
@onready var light_detect: Node3D = $"."

func _process(delta: float) -> void:
	
	# The following code will take a screenshot of our camera and create an array of floats
	# that will be used to average the float values so we can determine our general lightness
	# values. Obs: An image is like an array of pixels
	#var image : Image = get_node("SubViewportContainer/SubViewport").get_texture().get_image()
	
	camera_3d.global_position = light_detect.global_position + Vector3(0,1.3,0)
	
	var LightDetectSV : SubViewport = get_tree().get_nodes_in_group("LightDetectSubViewport")[0]
	
	var image : Image = LightDetectSV.get_texture().get_image()
	
	var floats : Array[float]
	
	for y in range(0, image.get_height()):
		for x in range (0, image.get_width()):
			var pixel = image.get_pixel(x,y)
			var lightValue = (pixel.r + pixel.g + pixel.b) / 3
			floats.append(lightValue)
	return average(floats)
	pass

func average(numbers: Array[float]) :
	var sum = 0.0
	for n in numbers:
		sum += n
	return sum / numbers.size()

xyz

xyz In what way it didn't work?

The lightValue is always zero and the floats array is always [0,0,0,...0]. There values should be in a 0 to 1 interval.

xyz Also why do you return something from _process() whose return value is declared void?

I should probably have made the floats array a "public" global variable instead of trying to return something. It needs to be read by other scripts.