extends Node3D

# Creates horizontal caustic planes at multiple depths, follows the player
# Add as child of any node that follows the player (e.g. PlanktonFollower)

const LAYER_DEPTHS := [-5.0, -15.0, -25.0]
const LAYER_SIZE := 60.0

var caustic_meshes: Array[MeshInstance3D] = []
var caustic_material: ShaderMaterial

func _ready() -> void:
	var shader := load("res://shaders/caustics.gdshader")
	if not shader:
		push_warning("CausticsLayer: caustics.gdshader not found")
		return

	caustic_material = ShaderMaterial.new()
	caustic_material.shader = shader

	for depth in LAYER_DEPTHS:
		var mi := MeshInstance3D.new()
		var plane := PlaneMesh.new()
		plane.size = Vector2(LAYER_SIZE, LAYER_SIZE)
		mi.mesh = plane
		# Each layer gets its own material instance to allow per-depth tuning
		var mat := caustic_material.duplicate() as ShaderMaterial
		# Lower layers = less intense
		var fade := clamp(1.0 + depth / 30.0, 0.0, 1.0)
		mat.set_shader_parameter("intensity", 1.5 * fade)
		mi.material_override = mat
		mi.position = Vector3(0.0, depth, 0.0)
		add_child(mi)
		caustic_meshes.append(mi)

func _process(_delta: float) -> void:
	# Follow camera XZ, keep fixed Y depths
	var cam := get_viewport().get_camera_3d()
	if cam:
		var cx := cam.global_position.x
		var cz := cam.global_position.z
		for i in caustic_meshes.size():
			var mi := caustic_meshes[i]
			mi.global_position.x = cx
			mi.global_position.z = cz
			# Keep the fixed depth offset
			mi.global_position.y = LAYER_DEPTHS[i]