# Weather (P9) —— 雪 / 雨 环境粒子。跟随相机，在其上方一片区域内下落。
#
#   var w := preload("res://fx/weather.gd").new()
#   add_child(w)
#   w.setup(camera)          # camera: Camera3D / Node3D
#   w.set_weather("snow")    # "snow" | "rain" | "none"
#
# 用 GPUParticles3D + ParticleProcessMaterial 的盒子发射体，粒子朝下。
# 由地图属性或调试驱动；没有专门封包。
extends Node3D

var _cam: Node3D
var _p: GPUParticles3D
var _kind := "none"

func setup(camera: Node3D) -> void:
	_cam = camera
	_p = GPUParticles3D.new()
	_p.amount = 800
	_p.lifetime = 3.0
	_p.visibility_aabb = AABB(Vector3(-30, -30, -30), Vector3(60, 60, 60))
	_p.local_coords = false
	_p.emitting = false
	add_child(_p)
	_build_material()
	set_weather("none")

func kind() -> String:
	return _kind

func set_weather(k: String) -> void:
	_kind = k
	if _p == null:
		return
	if k == "none":
		_p.emitting = false
		return
	_p.emitting = true
	var m: ParticleProcessMaterial = _p.process_material
	if k == "snow":
		_p.amount = 700
		_p.lifetime = 6.0
		m.gravity = Vector3(0, -2.0, 0)
		m.initial_velocity_min = 0.5
		m.initial_velocity_max = 1.5
		m.scale_min = 0.03
		m.scale_max = 0.08
		m.color = Color(1, 1, 1, 0.9)
		m.turbulence_enabled = true
		m.turbulence_noise_strength = 0.6
	elif k == "rain":
		_p.amount = 1200
		_p.lifetime = 1.2
		m.gravity = Vector3(0, -30.0, 0)
		m.initial_velocity_min = 12.0
		m.initial_velocity_max = 18.0
		m.scale_min = 0.015
		m.scale_max = 0.03
		m.color = Color(0.7, 0.8, 0.95, 0.5)
		m.turbulence_enabled = false

func _build_material() -> void:
	var m := ParticleProcessMaterial.new()
	m.emission_shape = ParticleProcessMaterial.EMISSION_SHAPE_BOX
	m.emission_box_extents = Vector3(25, 1, 25)
	m.direction = Vector3(0, -1, 0)
	m.spread = 8.0
	m.gravity = Vector3(0, -2.0, 0)
	_p.process_material = m
	var mesh := QuadMesh.new()
	mesh.size = Vector2(0.1, 0.1)
	var mat := StandardMaterial3D.new()
	mat.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
	mat.transparency = BaseMaterial3D.TRANSPARENCY_ALPHA
	mat.billboard_mode = BaseMaterial3D.BILLBOARD_ENABLED
	mat.albedo_color = Color(1, 1, 1, 0.85)
	mesh.material = mat
	_p.draw_pass_1 = mesh

func _process(_dt: float) -> void:
	if _cam and _p:
		# 发射体盒子锚在相机上方 20m
		_p.global_position = _cam.global_position + Vector3(0, 20, 0)