参考

原文地址：https://www.bilibili.com/read/cv15683152?spm_id_from=333.999.0.0
本篇用语雀“备份”了@张学徒(zhangxuetu)的状态机写法，在部分代码排版和注释风格上做了一定修改。并添加了原文没有的一些注释，方便查看和会意。
可以参照9.状态机初步一文，对照学习。

状态机

  1. #============================================================
  2. #    State Machine
  3. #============================================================
  4. #  状态机
  5. #============================================================
  6. # @datetime: 2022-3-15 17:02:55
  7. #============================================================
  9. class_name StateMachine
  10. extends Node
  12. signal state_changed(last_state, current_state)
  14. var current_state                # 当前状态
  15. var current_state_node : State   # 当前状态对应的节点
  16. var blackboard : StateBlackboard setget , get_blackboard    # 状态黑板
  17. var states := {}  # 所有可用状态的字典              
  21. #============================================================
  22. #   Set/Get
  23. #============================================================
  24. func get_state_node_list() -> Array:  # 获取所有可用状态的节点的数组
  25.     return states.values()
  27. func get_blackboard():         # 获取状态黑板     
  28.     if blackboard == null:
  29.         for child in get_children():
  30.             if child is StateBlackboard:
  31.                 blackboard = child
  32.     return blackboard
  34. func get_state_node(state) -> State:   # 返回状态名称对应的节点
  35.     return states[state] as State
  39. #============================================================
  40. #   内置
  41. #============================================================
  42. func _ready():
  43.     # 找到所有子状态机记录到states字典
  44.     for child in get_children():
  45.         if child is State:
  46.             states[child.name] = child
  48.     # 如果存在至少1个状态  -- 默认进入第一个状态
  49.     if states.size() > 0:
  50.         current_state = states.keys()[0]
  51.         current_state_node = get_state_node(current_state)
  52.         current_state_node.enter(null)
  53.     else:
  54.         set_physics_process(false)
  55.         printerr("没有添加状态节点，状态机没有启动")
  57. # 只执行当前状态的物理帧处理过程
  58. func state_process(delta):
  59.     current_state_node.state_process(delta)
  63. #============================================================
  64. #   自定义
  65. #============================================================
  66. # 切换状态
  67. func switch_to(state, data: Dictionary = {}):
  68.     if state != current_state:  # 如果新的状态不是现在的状态
  69.         current_state_node.exit()    # 判断当前状态的节点存在
  70.         emit_signal("state_changed", current_state, state)
  72.         current_state = state # 将状态记录为当前状态
  73.         current_state_node = get_state_node(current_state)   # 记录状态节点为当前状态的节点
  74.         current_state_node.enter(data)  # 调用当前状态的进入

状态基类

  1. #============================================================
  2. # State 状态基类 @datetime: 2022-3-15 17:03:14  张学徒  巽星石部分修改，用于展示
  3. #============================================================
  4. class_name State
  5. extends Node
  7. onready var state_machine = get_parent() # 获取和记录StateMachine对象
  10. #============================================================
  11. #   Set/Get
  12. #============================================================
  13. # 获取状态机对象
  14. func get_state_machine():
  15.     return state_machine
  17. # 获取状态机的当前状态
  18. func get_current_state() -> State:
  19.     return state_machine.get_current_state() as State
  21. # 获取状态黑板
  22. func get_blackboard():
  23.     return get_state_machine().get_blackboard() as StateBlackboard
  25. #============================================================
  26. #   核心代码
  27. #============================================================
  28. # 物理帧处理
  29. func state_process(delta):
  30.     pass
  32. # 进入状态
  33. func enter(data):
  34.     pass
  36. # 退出状态
  37. func exit():
  38.     pass
  40. # 切换状态
  41. func switch_to(state, data: Dictionary = {}):
  42.     state_machine.switch_to(state, data)

可以看到，张学徒的代码更灵活，给予了状态基类更多的权限，比如自己切换状态，获取当前状态等等。

状态黑板类

另外张学徒还引入了一个叫做“StateBlackboard（状态黑板）”的额外类型，说是用于存储状态机的全局数据。

  1. #============================================================
  2. #    Blackboard 状态黑板 @datetime: 2022-3-15 17:31:58
  3. #============================================================
  4. class_name StateBlackboard
  5. extends Node
  7. var data : Dictionary = {}
  9. func _enter_tree():
  10.     get_parent().blackboard = self # 赋值状态机的blackboard属性为自己

在做的时候，我会创建对应类型的状态机、状态和对应的黑板。比如我要给 Player 节点设计状态机，我会先创建对应的 PlayerStateMachine（Player状态机）、PlayerState（Player状态基类）、PlayerBlackboard（Player状态机黑板）。 ——@张学徒(zhangxuetu)

image.png

PlayerState的推测

原文的下半部分没有贴出完整的代码，所以联系作者要了项目源码，然而，部分设计已经修改，所以类名也有所修改，所以只好贴出项目中的源码。

  1. #============================================================
  2. #    PlayerBaseState
  3. #============================================================
  4. # * 这是这个状态机的基础状态类，默认添加到场景中，便于修改这个类型中的属性
  5. #     和方法。
  6. #============================================================
  7. # @datetime: 2022-5-1 22:35:53
  8. #============================================================
  9. class_name PlayerBaseState
  10. extends BaseExecuteState
  13. var controller : PlayerController
  14. var input : InputController
  16. var attack_wrapper : AttackWrapper
  17. var equipment_wrapper : EquipmentWrapper
  18. var property_wrapper : PropertyWrapper
  20. var type_layer : PlayerTypeLayer
  23. #============================================================
  24. #   Set/Get
  25. #============================================================
  26. func get_host() -> Player:
  27.     return owner as Player
  29. func get_blackboard() -> PlayerStateBlackboard:
  30.     return .get_blackboard() as PlayerStateBlackboard
  32. func set_gravity_enabled(value: bool):
  33.     get_move_controller().gravity_enabled = value
  35. func get_layer() -> PlayerTypeLayer:
  36.     return owner.type_layer as PlayerTypeLayer
  38. func get_input_controller() -> InputController:
  39.     return input
  41. func get_move_controller() -> SimplePlatformController:
  42.     return controller.move_controller
  44. func is_moving() -> bool:
  45.     return controller.move_controller.is_moving()
  47. func is_on_floor() -> bool:
  48.     return get_host().is_on_floor()
  50. func is_falling():
  51.     return (
  52.         not get_host().is_on_floor()
  53.         or controller.move_controller.get_last_velocity().y > 0
  54.     )
  56. func is_can_jump() -> bool:
  57.     return controller.move_controller.jump_enabled
  59. func is_can_move() -> bool:
  60.     return controller.move_controller.move_enabled
  62. func is_can_fall() -> bool:
  63.     return (get_host() as KinematicBody2D).is_on_floor()
  65. func is_can_attack() -> bool:
  66.     return (attack_wrapper.is_enabled() 
  67.         and equipment_wrapper.get_type_items("weapon").size() > 0
  68.     )
  70. func is_on_stairs() -> bool:
  71.     return type_layer.collision.is_can_climb_stairs()
  73. func is_on_stairs_top() -> bool:
  74.     return type_layer.collision.is_on_stairs_top()
  76. func is_can_climb_stairs() -> bool:
  77.     return is_on_stairs() or is_on_stairs_top()
  79. func is_can_climb_wall() -> bool:
  80.     return get_host().is_on_wall()
  83. #============================================================
  84. #   内置
  85. #============================================================
  86. func _ready():
  87.     # 等待 Player 中的 onready 节点都加载完成
  88.     yield(owner, "ready")
  89.     controller = get_layer().controller
  90.     input = get_layer().controller.input_controller
  91.     type_layer = get_host().type_layer
  93.     attack_wrapper = WrapperHelper.get_attack(owner)
  94.     equipment_wrapper = WrapperHelper.get_equipment(owner)
  95.     property_wrapper = WrapperHelper.get_property(owner)
  98. #============================================================
  99. #   状态方法
  100. #============================================================
  101. #(override)
  102. func enter():
  103. #    printerr("进入到状态：", name)
  104.     pass
  106. #(override)
  107. func exit():
  108. #    printerr("退出状态：", name)
  109.     pass
  112. #============================================================
  113. #   自定义
  114. #============================================================
  115. ##  移动
  116. func input_move() -> bool:
  117.     var direction : float = Input.get_axis(input.input_left, input.input_right)
  118.     if direction and is_can_move():
  119.         controller.move(direction)
  120.         return true
  121.     return false
  124. ##  跳跃
  125. func input_jump() -> bool:
  126.     if (Input.is_action_pressed(input.input_up)
  127.         and is_can_jump()
  128.     ):
  129.         if controller.jump():
  130.             return true
  131.     return false
  134. ##  下落
  135. func input_fall() -> bool:
  136.     if (Input.is_action_pressed(input.input_down)
  137.         and is_can_fall()
  138.     ):
  139.         controller.fall()
  140.         return true
  141.     return false
  144. ##  发出攻击
  145. func input_attack() -> bool:
  146.     if (Input.is_action_pressed(get_blackboard().input_attack)
  147.         and is_can_attack()
  148.     ):
  149.         attack_wrapper.attack()
  150.         return true
  151.     return false
  154. ##  爬楼梯
  155. func input_climb_stairs() -> bool:
  156.     var dir = Input.get_axis(input.input_up, input.input_down)
  157.     if is_can_climb_stairs():
  158.         if ((dir < 0 and not is_on_stairs_top()) # 向上移动
  159.             or dir > 0    # 向下移动
  160.         ):
  161.             get_host().move_and_slide(
  162.                 Vector2(0, property_wrapper.get_property("move_speed") * dir)
  163.                 , Vector2.UP
  164.             )
  165.             return true
  166.     return false
  169. ##  爬墙
  170. func input_climb_wall():
  171.     if (is_can_climb_wall()
  172.         and Input.is_action_pressed(input.input_up)
  173.     ):
  174.         get_move_controller().jump(
  175.             # 爬墙速度为 jump_height 的 0.6
  176.             0.6 * property_wrapper.get_property('jump_height')
  177.             , true
  178.         )
  179.         return true
  180.     return false
  1. #============================================================
  2. #    PlayerIdle
  3. #============================================================
  4. # @datetime: 2022-4-26 00:59:06
  5. #============================================================
  6. class_name PlayerIdle
  7. extends PlayerBaseState
  10. #(override)
  11. func state_process(_arg0):
  12.     set_gravity_enabled(not is_on_stairs_top())
  14.     if input_fall():
  15.         if is_on_stairs_top():
  16.             switch_to(PlayerStateBlackboard.States.CLIMB_STARIS)
  18.     if input_jump():
  19.         switch_to(PlayerStateBlackboard.States.JUMP)
  20.     elif input_attack():
  21.         switch_to(PlayerStateBlackboard.States.ATTACK)
  22.     elif input_climb_stairs():
  23.         switch_to(PlayerStateBlackboard.States.CLIMB_STARIS)
  24.     elif input_climb_wall():
  25.         switch_to(PlayerStateBlackboard.States.CLIMB_WALL)
  26.     elif input_move():
  27.         switch_to(PlayerStateBlackboard.States.MOVE)