godot-plateformer/addons/reedcomponent/grap_hook/garpping_hook_v_2.gd

class_name Hook extends Node2D

## ================
## Export Field
## ================
@export var min_length := 140
@export var max_length := 200
@export var streching_speed:float = 1400

## 线段
@onready var line_2d: Line2D = %Line2D
## 检测碰撞的区域
@onready var area_2d: Area2D = %Area2D


const GRAPABLE_GROUP = &"GRAPABLE"
const ANCHOR_NODE = preload("uid://dfm5wy1rmci68")

signal stretching_finished(reach_limit:bool, anchor_node: Node2D)

## ================
## Private Field
## ================
var _binded_hook_comp
var _is_stretching: bool = false
var _stretching_dir: Vector2 = Vector2.ZERO
var _cached_cancel: bool = false
var _anchor: Node2D

func _ready() -> void:
	area_2d.position = Vector2.ZERO
	
	area_2d.area_entered.connect(grap_detected)
	area_2d.body_entered.connect(grap_detected)

##初始化
func init(hook_comp:SpawnHookComponet,reset_to_target: bool):
	
	_binded_hook_comp = hook_comp
	if reset_to_target:
		var p : Vector2= hook_comp.owner.global_position
		self.global_position = p

##开始stretching
func start_stretching(direction: Vector2) -> void:
	_is_stretching = true
	_cached_cancel = false
	_stretching_dir = direction

##结束stretching
func end_stretching(force_end: bool = false) -> bool:
	
	##如果还没有达到最短的stretching length，则继续
	if not force_end and _is_stretching:
		var d = self.global_position.distance_to(area_2d.global_position)
		if d < min_length:
			_cached_cancel = true
			return false
		
	_is_stretching = false
	_stretching_dir = Vector2.ZERO
	return true

##是否正在stretching
func is_stretching() -> bool:
	return _is_stretching

##物理更新
func _physics_process(delta: float) -> void:
	if _is_stretching:
		_update_stretching(delta)

##更新绳索的动画表现
func _process(delta: float) -> void:
	update_line_target_pos_with_index(0,self.global_position)
	update_line_target_pos_with_index(1,area_2d.global_position)

##更新钩爪爪手的位置
func _update_stretching(delta: float) -> void:
	var d = self.global_position.distance_to(area_2d.global_position)
	
	#如果已经存在一个缓存的取消，且当前的长度小于最小长度，则直接取消
	if _cached_cancel:
		if d >= min_length:
			stretching_finished.emit(true,null)
			end_stretching(true)
			return
	
	#如果达到的最大的长度，直接取消
	if d > max_length:
		stretching_finished.emit(true,null)
		end_stretching(true)
		return
	
	area_2d.global_position += delta * streching_speed * _stretching_dir

## ================
## Tool Func
## ================

##更新特定点的位置
func update_line_target_pos_with_index(point_index: int, target_pos: Vector2) -> void:
	line_2d.set_point_position(
		point_index,
		target_pos - global_position
	)

##当触碰到可以被抓握的Area后，自动在当前位置生成一个钩爪锚点，后续的移动交给其他系统
func grap_detected(node: Node2D) -> void:
	if node.is_in_group(GRAPABLE_GROUP):
		end_stretching(true)
		var d : float= self.global_position.distance_to(area_2d.global_position)
		var b = d == max_length
		
		var anchor := _create_anchor_on_node(node)
		if anchor:
			stretching_finished.emit(b,anchor)

##创建钩爪锚点
func _create_anchor_on_node(area: Node2D) -> Node2D:
	# 如果之前有锚点，先清掉
	if _anchor and is_instance_valid(_anchor):
		_anchor.queue_free()

	# 1. 创建 Anchor
	_anchor = Node2D.new()
	_anchor.name = "Anchor"
	add_child(_anchor)

	# 2. Anchor 初始位置 = Area 当前世界位置
	_anchor.global_position = area.global_position

	# 3. 在 Area 上挂 RemoteTransform2D
	var remote := RemoteTransform2D.new()
	remote.name = "AnchorRemote"
	area.add_child(remote)

	remote.remote_path = _anchor.get_path()

	# 4. 只同步位置（锚点一般不需要跟旋转/缩放）
	remote.update_rotation = false
	remote.update_scale = false

	return _anchor