在Actionscript 3遊戲中只設置一次變量？

Question

我正在嘗試創建一個簡單的遊戲。我已經設置了一個圖層「動作腳本」，我把所有的代碼放在裏面。然後我有一個圖像，實例名稱是「玩家」。這裏是我的代碼：

stage.addEventListener(KeyboardEvent.KEY_DOWN,KeyDown); 

var power = 5; 
var friction = 0.95; 

var xspeed = 0; 
var yspeed = 0; 

function KeyDown(keyEvent:KeyboardEvent) { 
if(keyEvent.keyCode==37) { //left 
     xspeed -= power; 
    } 
    if(keyEvent.keyCode==39) { //right 
     xspeed += power; 
} 

xspeed *= friction; 

player.x += xspeed; 

//trace(keyEvent.keyCode.toString()); 
} 

突然，腳本重置xspeed（和yspeed）每一次這樣的速度無法上升或下降。如何防止這一點？

我想我的翅膀在ActionScript中，所以我想有一些提示和幫助:)

馬爾蒂·萊恩

Answer 1

我覺得你的問題是，你有你的時間表一幀以上，所以每次播放頭移動到另一幀時，腳本都會再次運行，一切都基本重置。

這是我會怎麼做（如果你願意嘗試一些更高級）：
第一招確保沒有在舞臺上被選中，找到標Class:場下的PUBLISH標題
粘貼文字DocumentClass。
現在和你的fla文件在同一個目錄下創建一個文件名DocumentClass.as
然後粘貼下面的內容，保存並運行fla文件。

package { 
import flash.display.MovieClip; 
import flash.events.Event; 
import flash.events.KeyboardEvent; 

// Start class 
// This class must extend MovieClip 
public class DocumentClass extends MovieClip{ 
    private var acceleration:Number = 2; 
    private var friction:Number = 0.95; 
    // Limits the player's speed to prevent it from moving too fast 
    private var maxSpeed:Number = 6; 

    // The players velocity 
    private var playerSpeedX:Number = 0; 
    private var playerSpeedY:Number = 0; 

    // Keeps track of what keys are pressed 
    private var keyLeft:Boolean; 
    private var keyRight:Boolean; 

    // The contructor for DocumentClass - this is automatically called 
    public function DocumentClass(){ 
     addEventListener(Event.ENTER_FRAME, eventEnterFrame, false, 0, true); 
     stage.addEventListener(KeyboardEvent.KEY_DOWN, eventKeyDown, false, 0, true); 
     stage.addEventListener(KeyboardEvent.KEY_UP, eventKeyUp, false, 0, true); 
    } 

    // This function is called when a key is pressed 
    private function eventKeyDown(keyEvent:KeyboardEvent):void{ 
     switch(keyEvent.keyCode){ 
      // Left 
      case 37: keyLeft = true; break; 
      // Right 
      case 39: keyRight = true; break; 
     } 
    } 
    // This function is called when a key is released 
    private function eventKeyUp(keyEvent:KeyboardEvent):void{ 
     switch(keyEvent.keyCode){ 
      // Left 
      case 37: keyLeft = false; break; 
      // Right 
      case 39: keyRight = false; break; 
     } 
    } 

    // This function is called every frame. 
    // Move the player every frame instead of in the keyboard events. 
    private function eventEnterFrame(event:Event):void{ 
     // If the left key is pressed and the player's speed is under the limit. 
     if(keyLeft && playerSpeedX > -maxSpeed) 
      playerSpeedX -= acceleration; 
     // Otherwise if the right key is pressed and the player's speed is under the limit. 
     else if(keyRight && playerSpeedX < maxSpeed) 
      playerSpeedX += acceleration; 

     playerSpeedX *= friction; 

     // I find that when the playerSpeedX values start to get really small the player 
     // will seems to just slowly move for a long so I clip the speed when it becomes very small 
     if(playerSpeedX < 0.1 && playerSpeedX > -0.1) playerSpeedX = 0; 

     player.x += playerSpeedX; 
    } 


}// End class 

} 

當然，如果，在我修改原密碼一點點的那一刻有點超出你：

stage.addEventListener(KeyboardEvent.KEY_DOWN, eventKeyDown); 
stage.addEventListener(KeyboardEvent.KEY_UP, eventKeyUp); 
addEventListener(Event.ENTER_FRAME, eventEnterFrame); 

var power:Number = 5; 
var friction:Number = 0.95; 

var keyLeft:Boolean; 
var keyRight:Boolean; 

var xspeed:Number = 0; 
var yspeed:Number = 0; 

function eventKeyDown(keyEvent:KeyboardEvent):void{ 
    // Left 
    if(keyEvent.keyCode==37){ 
     keyLeft = true; 
    } 
    // Right 
    if(keyEvent.keyCode==39){ 
     keyRight = true; 
    } 
} 

function eventKeyUp(keyEvent:KeyboardEvent):void{ 
    // Left 
    if(keyEvent.keyCode==37){ 
     keyLeft = false; 
    } 
    // Right 
    if(keyEvent.keyCode==39){ 
     keyRight = false; 
    } 
} 

function eventEnterFrame(event:Event):void{ 
    if(keyLeft) xspeed -= power; 
    if(keyRight) xspeed += power; 

    xspeed *= friction; 

    if(xspeed < 0.1 && xspeed > -0.1) xspeed = 0; 

    player.x += xspeed; 
}