parallax starfield in Godot 4

starfield.gd

@tool
extends ParallaxBackground

@export
var star_colors: Array[Color] = [Color(1, 1, 1, 1), Color(0.8, 0.8, 1, 1), Color(1, 0.8, 0.8, 1)]
@export_range(10, 500) var num_stars_per_layer: int = 300
@export_range(0.1, 2.0) var twinkle_frequency: float = 2.0
@export var parallax_speeds: Array[float] = [0.1, 0.3, 0.6]

var viewport_size: Vector2
var stars: Array[Array] = []
var twinkle_times: Array[Array] = []


func _ready() -> void:
	viewport_size = get_viewport().get_visible_rect().size

	# Create three parallax layers
	for i in range(3):
		var parallax = ParallaxLayer.new()
		parallax.motion_scale = Vector2(parallax_speeds[i], parallax_speeds[i])
		add_child(parallax)

		# Create stars for this layer
		var layer_stars = []
		var layer_twinkle_times = []

		for _j in range(num_stars_per_layer):
			var star = ColorRect.new()
			star.size = Vector2(2, 2)
			star.position = Vector2(
				randf() * viewport_size.x * 2 - viewport_size.x,
				randf() * viewport_size.y * 2 - viewport_size.y
			)
			star.color = star_colors[randi() % star_colors.size()]
			parallax.add_child(star)
			layer_stars.append(star)
			layer_twinkle_times.append(randf() * twinkle_frequency)

		stars.append(layer_stars)
		twinkle_times.append(layer_twinkle_times)


func _process(delta: float) -> void:
	# Update star twinkle effect
	for layer_idx in range(stars.size()):
		for star_idx in range(stars[layer_idx].size()):
			twinkle_times[layer_idx][star_idx] -= delta
			if twinkle_times[layer_idx][star_idx] <= 0:
				var star = stars[layer_idx][star_idx]
				star.color.a = randf_range(0.3, 1.0)
				twinkle_times[layer_idx][star_idx] = randf() * twinkle_frequency