【Godot4自学手册】第二十二节完成主人公的闪现功能-编程知识

这一节我们主要自学主人公的闪现功能，当按下鼠标右键，我们的主人公根据不同的方向进行瞬间移动，并在身后留下一串残影，具体效果如下：
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一、新建ghost场景

新建Node2D场景，命名为Ghost，存储到Scenes目录下。然后在根节点下添加4个Sprite2D精灵结点，用来展示主人公四个方向的图片，并在检查器中将Visibility->Visble关闭。
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然后为根节点添加脚本，存到Scriptes目录下命名为ghost，编写如下代码：

extends Node2D
var playerN=1 #定义显示的主任公func _ready():#创建间补动画将主人公透明0.5秒后变为0var tween = create_tween()tween.tween_property(self,"modulate:a",0,0.5)tween.tween_callback(queue_free) func setShow(playernumber):#设置第几个Sprite2D显示get_node("Player"+str(playernumber)).visible=true

二、在Player场景编写代码

首先切换到Player场景，给根节点添加Timer结点，并命名为DashTime，在其检查器中将Timer->Wait Time设置为0.05，表示每0.05秒执行一次Timeout函数。然后切换到结点信号双击timeout信号，弹出对话框选择Player结点，然后单击连接按钮。
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这样会在Player代码中添加func _on_dash_time_timeout()函数，然后编写代码如下：

func _on_dash_time_timeout():if dash_time > 0: #当闪现时间大于0时dash_time -= 1 #闪现时间减1var ghost = Ghost.instantiate() #实例化Ghost场景ghost.global_position = global_position #设置ghost节点位置为当前主人公位置if playerDirecion.x==1: #主人公面向右侧，对应设置ghost内Sprite2D图片向右ghost.setShow(1)elif  playerDirecion.x==-1:#主人公面向左侧，对应设置ghost内Sprite2D图片向做ghost.setShow(2)elif  playerDirecion.y==-1:#主人公面向下方，对应设置ghost内Sprite2D图片向下ghost.setShow(4)elif  playerDirecion.y==1:#主人公面向上方，对应设置ghost内Sprite2D图片向上ghost.setShow(3)else:ghost.setShow(1)			Globals.duplicate_node.add_child(ghost)#将实例化的ghost结点添加到主场景中显示else: #当闪现时间结束时velocity.x = 0 #设置速度为0dash_time = 5 #闪现时间重新计时$DashTime.stop() #DashTime停止state=IDLE #主人公切换到等待状态

在该函数调用前需要定义一些变量如下：

#预先加载ghost场景
var Ghost = preload("res://Scenes/ghost.tscn")
#定义闪现速度
var dash_speed = 300
#闪现时间为5
var dash_time=5

在_physics_process函数添加如下代码：

if state!=DASH and state!=HURT:if Input.is_action_just_pressed("dash"):state = DASH

编写函数dash_state函数

func dash_state():velocity = Vector2.ZERO #将速度设为0$DashTime.start() #启动计时器if playerDirecion.x <0: #当主人公面向右，x轴速度减去闪现速度velocity.x -= dash_speedelif playerDirecion.x>0: #当主人公面向左侧，x轴度减去闪现速度velocity.x += dash_speedelif playerDirecion.y>0:#当主人公面向下方，y轴度加上闪现速度velocity.y += dash_speedelif  playerDirecion.y<0:#当主人公面向上方，y轴度减去闪现速度velocity.y -= dash_speed	else:velocity.x -= dash_speed #默认pass

经过上面的步骤就完成了闪现残影效果，整改Player代码如下：

extends CharacterBody2D
@onready var anima_tree=$AnimationTree
@onready var animation_player = $AnimationPlayer
@onready var stats = $Stats
var playerDirecion = Vector2(-1,0)
var direcion = Vector2.ZERO
var Ghost = preload("res://Scenes/ghost.tscn")
enum {IDLE,WALK,SWORD,HURT,DASH}
var dash_speed = 300
var dash_time=5
var state = IDLE:set(v):state=vmatch  state:IDLE:idle_state()WALK:walk_state()SWORD:sword_state()HURT:hurt_state()DASH:dash_state()const SPEED = 120.0
var enemyPositon
var knockback=200func _ready():Globals.last_Player = positionfunc _physics_process(delta):	direcion = Vector2.ZEROdirecion.x = Input.get_axis("left", "right")direcion.y = Input.get_axis("up", "down")if state!=SWORD and state!=HURT and state !=DASH:if direcion:anima_tree.set("parameters/Idle/blend_position",direcion)anima_tree.set("parameters/Walk/blend_position",direcion)anima_tree.set("parameters/Sword/blend_position",direcion)anima_tree.set("parameters/Hurt/blend_position",Vector2(direcion.x*-1,direcion.y))state = WALKplayerDirecion = direcionelse:velocity=Vector2.ZEROstate=IDLEif Input.is_action_just_pressed("sword"):velocity= Vector2.ZEROstate = SWORDif state!=DASH and state!=HURT:if Input.is_action_just_pressed("dash"):state = DASHGlobals.last_Player = positionmove_and_slide()	func idle_state():#待机状态anima_tree["parameters/playback"].travel("Idle")
func walk_state():#行走状态anima_tree["parameters/playback"].travel("Walk")velocity = direcion * SPEED	func sword_state():#进攻状态anima_tree["parameters/playback"].travel("Sword")await anima_tree.animation_finished	state=IDLEfunc hurt_state():#受伤状态var dir = enemyPositon.direction_to(global_position).normalized()anima_tree["parameters/playback"].travel("Hurt")if dir.x>0:velocity.x +=knockbackelse:velocity.x -=knockbackawait anima_tree.animation_finishedstats.health -=10	state=WALK
func dash_state():velocity = Vector2.ZERO$DashTime.start()if playerDirecion.x <0:velocity.x -= dash_speedelif playerDirecion.x>0:velocity.x += dash_speedelif playerDirecion.y>0:velocity.y += dash_speedelif  playerDirecion.y<0:velocity.y -= dash_speed	else:velocity.x -= dash_speedpassfunc _on_hurt_box_area_entered(area):enemyPositon = area.owner.global_positionstate=HURT	func hit_effect():$Camera2D._hit(Vector2(1.99,1.99),Vector2(7,-9))$Camera2D.frameFreeze(0.1,0.09)func _on_dash_time_timeout():if dash_time > 0:dash_time -= 1var ghost = Ghost.instantiate()ghost.global_position = global_positionif playerDirecion.x==1:ghost.setShow(1)elif  playerDirecion.x==-1:ghost.setShow(2)elif  playerDirecion.y==-1:ghost.setShow(4)elif  playerDirecion.y==1:ghost.setShow(3)else:ghost.setShow(1)			Globals.duplicate_node.add_child(ghost)else:velocity.x = 0dash_time = 5$DashTime.stop()state=IDLE

同学们这节就到这了，下节见。