AS3 -在使用基本游戏类时遇到问题

Question

所以我正在创建一个太空射击游戏。我的文档类是Engine，它看起来像这样：

package Classes
{

import flash.display.MovieClip;
import flash.display.Stage;
import flash.events.Event;
import flash.events.MouseEvent;

public class Engine extends MovieClip
{

    private var startMenu:StartMenu;
    private var numberOfStars:int = 80;
    public static var enemyList:Array = new Array();
    private var spaceShip:Ship;
    private var hud:HUD;

    public function Engine()
    {
        startMenu = new StartMenu();
        stage.addChild(startMenu);
        startMenu.x = (stage.stageWidth / 2);
        startMenu.y = (stage.stageHeight / 2);
    }

    private function startGame()
    {
        stage.removeChild(startMenu)
        spaceShip = new Ship(stage);
        stage.addChild(spaceShip);
        spaceShip.x = (stage.stageWidth / 2);
        spaceShip.y = (stage.stageHeight / 2);

        spaceShip.addEventListener("hit", shipHit);

        hud = new HUD(stage); //create the HUD
        stage.addChild(hud); //and display it.

        for (var i:int = 0; i < numberOfStars; i++)
        {
            stage.addChildAt(new Star(stage), 1);
        }

        addEventListener(Event.ENTER_FRAME, createFighter);
    }
}

如您所见，我正在调用另一个名为StartMenu的类。这就是我遇到麻烦的地方:以下是代码(或缺少)

package  Classes
{
import flash.display.MovieClip;
import flash.display.Stage;
import flash.events.Event;
import flash.events.MouseEvent;
import flash.events.*;

public class StartMenu extends MovieClip
{

    public function StartMenu()
    {
        button1.addEventListener(MouseEvent.CLICK, buttonClicked);
    }

    private function buttonClicked(e:MouseEvent)
    {

    }



}

}

(忽略缩进错误，它在真实代码中是正确的)好的，那么想象一下屏幕上显示了一个按钮。此按钮是StartMenu类的一部分，用于侦听MouseEvent.CLICK。

单击按钮后，我需要以某种方式返回到Engine类并调用函数startGame()，但我不能只执行Engine.startGame()，我已经尝试将该函数设置为公共函数，并且尝试将该函数设置为公共静态函数。不走运。请帮帮忙？？任何方法都可以，我只需要一种方法，让这个类在按钮被单击后转到startGame函数！

Answer 1

最快的方法可能是将引擎变量添加到StartMenu类中，并通过开始菜单的构造函数传递引擎。下面是一个简短的代码示例：

StartMenu

public class StartMenu extends MovieClip
{

   private var _engine:Engine // add a new variable to the start menu class
   public function StartMenu(engine:Engine) // add a new parameter to the constructor
   {
      _engine = engine; // set the variable to the value passed through the constructor
      button1.addEventListener(MouseEvent.CLICK, buttonClicked);
   }

   private function buttonClicked(e:MouseEvent)
   {
      _engine.startGame()
   }
}

引擎

public function Engine()
{
    startMenu = new StartMenu(this); 
    // pass through the current instance of engine using the this keyword
    ...
}

public function startGame() // change private to public
{
    ...
}

我希望这对你有帮助

Answer 2

在您的Engine.as类中，您可以放置：

public static var instance:Engine;

public static function getInstance():Engine
{
  return instance as Engine;
}

在engine类的构造函数put中：

instance = this;

现在，您可以通过以下方式在项目中的任何位置使用Engine类以及所有公共函数和变量的实例：

Engine.getInstance().startGame();

它可以帮助你。

Answer 3

有两种类型的解决这种情况。一种是使用父引用或特定引用来调用某个函数，如Ethan Worley和Worley，另一种是使用可自定义的公共clicker setter，如下所示：

public class StartMenu extends MovieClip
{

    private var button1:MovieClip; // or whatever type your button is
    private var startGameFunction:Function;
    public function StartMenu()
    {
        // some initialization code if needed, including allocating button1
        startGameFunction=null;
        button1.addEventListener(MouseEvent.CLICK, buttonClicked);
    }

    public function set startGameClicked(value:Function):void {
        if (value==startGameFunction) return; // nothing to set
        startGameFunction=value;
    }
    private function buttonClicked(e:MouseEvent)
    {
        if (startGameFunction) startGameFunction(); // if there's a function assigned, call it
    }
}

引擎类：

public function Engine()
{
    startMenu = new StartMenu(); 
    startMenu.startGameFunction=this.startGame; 
    // no "()" here, as we are giving a function reference
    ...
}

public function startGame() // change private to public
{
    ...
}