extends Node
class_name CloudSunSync

## Keeps the fullscreen sky composite tied to the real DirectionalLight3D.
##
## The Environment sky shader receives LIGHT0_DIRECTION automatically, but the
## ink pass has to repaint background pixels after the screen copy. This bridge
## gives that second shader the same moving direction and color every frame.

var _sun: DirectionalLight3D
var _ink_material: ShaderMaterial
var _palette_sun_color := Color.WHITE


func configure(sun: DirectionalLight3D, ink_material: ShaderMaterial) -> void:
	_sun = sun
	_ink_material = ink_material
	var authored = ink_material.get_shader_parameter("sky_sun_color")
	if authored is Color:
		_palette_sun_color = authored
	_sync()


func _process(_delta: float) -> void:
	_sync()


func _sync() -> void:
	if not is_instance_valid(_sun) or not is_instance_valid(_ink_material):
		set_process(false)
		return

	# DirectionalLight3D shines down its local -Z axis, so +Z points back
	# toward the apparent sun—the direction a sky pixel uses for illumination.
	var toward_sun := _sun.global_transform.basis.z.normalized()
	_ink_material.set_shader_parameter("sky_sun_direction", toward_sun)

	# Preserve the authored day/sunset palette while allowing a dynamically
	# recolored sun to tint the cloud's lit face.
	var live_color := _palette_sun_color.lerp(_sun.light_color, 0.35)
	var energy_scale: float = clampf(_sun.light_energy / 1.4, 0.75, 1.25)
	_ink_material.set_shader_parameter(
			"sky_sun_color", live_color * energy_scale)