敌人和子弹电影剪辑冻结时子弹电影剪辑进入舞台-AS3-CS6

Question

我正在为大学作业做一个自上而下的射击。当我按下鼠标左键发射子弹时，当它们与玩家电影片段后面的敌人电影片段共线时，它们会冻结，当这种情况发生时，玩家电影片段仍然可以使用箭头键移动，这样SWF就不会崩溃。

敌人和子弹电影剪辑被放置在一个阵列中，并且在相互碰撞时都应该被移除。

在输出窗口中，当子弹头电影剪辑进入阶段时，我收到了这个错误消息

子弹击中坏蛋0

类型错误：错误#1034:类型强制失败：无法转换闪存。显示：：Stage@2862e041至flash.display.MovieClip.

在项目符号/removeSelf()

在项目符号/环()

在主/环路()

bullet hit baddie 0之所以存在，是因为它在代码中被跟踪。

Main.作为

package
{
import flash.display.Stage;
import flash.display.MovieClip;
import flash.events.Event;
import flash.events.MouseEvent;
public class Main extends MovieClip
{
public var player:Player;
public var enemy:Enemy;
public var bulletList:Array = [];
public var mousePressed:Boolean = false; //keeps track of whether the mouse is currently pressed down
public var delayCounter:int = 0; //this adds delay between the shots
public var delayMax:int = 7; //change this number to shoot more or less rapidly

var enemies:Array =  [];
public function Main():void
{
player = new Player(stage, 320, 240);
stage.addChild(player);
//stage.addEventListener(MouseEvent.CLICK, shootBullet, false, 0, true); //remove this
stage.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler, false, 0, true);
stage.addEventListener(MouseEvent.MOUSE_UP, mouseUpHandler, false, 0, true);
stage.addEventListener(Event.ENTER_FRAME, loop, false, 0, true);
for(var numBaddies=0; numBaddies<6;numBaddies++){
var enemy:Enemy = new Enemy(null);
enemy.x = numBaddies*50;
enemy.y = numBaddies*50
stage.addChild(enemy);
enemies.push(enemy);
}
}
public function loop(e:Event):void
{
if(mousePressed) // as long as the mouse is pressed...
{
delayCounter++; //increase the delayCounter by 1
if(delayCounter == delayMax) //if it reaches the max...
{
shootBullet(); //shoot a bullet
delayCounter = 0; //reset the delay counter so there is a pause between bullets

}
}
if(bulletList.length > 0)
{
for(var i:int = bulletList.length-1; i >= 0; i--)
{
bulletList[i].loop();
}
}

for(var h = 0; h<bulletList.length; ++h)
{
if(bulletList[h].hitTestObject(this)){
trace("player hit by baddie " + h);
}
}

for(var u:int=0; u<enemies.length; u++) {
Enemy(enemies[u]).moveTowards(player.x, player.y);
}
}

public function mouseDownHandler(e:MouseEvent):void //add this function
{
mousePressed = true; //set mousePressed to true
}
public function mouseUpHandler(e:MouseEvent):void //add this function
{
mousePressed = false; //reset this to false
}
public function shootBullet():void //delete the "e:MouseEvent" parameter
{
var bullet:Bullet = new Bullet(stage, player.x, player.y, player.rotation, enemies);
bullet.addEventListener(Event.REMOVED_FROM_STAGE, bulletRemoved, false, 0, true);
bulletList.push(bullet);
stage.addChild(bullet);
}
public function bulletRemoved(e:Event):void
{
e.currentTarget.removeEventListener(Event.REMOVED_FROM_STAGE, bulletRemoved);
bulletList.splice(bulletList.indexOf(e.currentTarget),1);
}
}
}

敌人

package  {
import flash.display.Stage;
import flash.display.MovieClip;
import flash.events.Event;
public class Enemy extends MovieClip {

public var bullets:Array;
public var stageRef:Stage;
private var enemyPositionX, enemyPositionY,xDistance,yDistance,myRotation:int;
public function Enemy(bulletList:Array) {
// constructor code
bullets = bulletList;
}

public function moveTowards(playerX:int, playerY:int){
xDistance = this.x - playerX;
yDistance = this.y - playerY;

myRotation = Math.atan2(yDistance, xDistance);
this.x -= 3 * Math.cos(myRotation);
this.y -= 3 * Math.sin(myRotation);


}
public function loopE():void{

for(var i=0; i<bullets.length; ++i)
{
if(bullets[i].hitTestObject(this)){
trace("you killed enemy " + i);
removeSelf();
}
}
}

private function removeSelf()
{
removeEventListener(Event.ENTER_FRAME, loopE);
if (stageRef.contains(this))
stageRef.removeChild(this);
}
}
}

项目符号，如

package
{
import flash.display.Stage;
import flash.display.MovieClip;
import flash.events.Event;
public class Bullet extends MovieClip
{
private var stageRef:Stage; //checks if the bullet leaves the screen borders
private var speed:Number = 10; //speed that the bullet will travel at
private var xVel:Number = 0; //current x velocity
private var yVel:Number = 0; //current y velocity
private var rotationInRadians = 0; //convenient to store our rotation in radians instead of degrees
private var allBaddies:Array;
//our constructor requires: the stage, the position of the bullet, and the direction the bullet should be facing
public function Bullet(stageRef:Stage, X:int, Y:int, rotationInDegrees:Number, enemies:Array):void
{
this.stageRef = stageRef;
this.x = X;
this.y = Y;
this.rotation = rotationInDegrees;
this.rotationInRadians = rotationInDegrees * Math.PI / 180; //convert degrees to radians, for trigonometry
allBaddies = enemies;
}

public function loop():void //we don't need to include the "e:Event" because we aren't using an EventListener
{
for(var b=0; b<allBaddies.length; ++b)
{
if(allBaddies[b].hitTestObject(this)){
trace("bullet hit baddie " + b);
removeSelf();
}
}

xVel = Math.cos(rotationInRadians) * speed; //uses the cosine to get the xVel from the speed and rotation
yVel = Math.sin(rotationInRadians) * speed; //uses the sine to get the yVel
x += xVel; //updates the position
y += yVel;
//if the bullet goes off the edge of the screen...
if(x > stageRef.stageWidth || x < 0 || y > stageRef.stageHeight || y < 0)
{
this.parent.removeChild(this); //remove the bullet
}
}

private function removeSelf()
{
removeEventListener(Event.ENTER_FRAME, loop);
if (MovieClip(root).stageRef.contains(this))
MovieClip(root).stageRef.removeChild(this);
}
}
}

感谢所有的帮助，并提前表示感谢。

Answer 1

由于root到MovieClip的强制转换失败，因此会得到TypeError。当你把一个变量放在括号里，前面有一个类型名时，你就断言这个对象是那个类型的(或扩展了那个类型)。在Bullet.removeSelf()函数中，您有：MovieClip(root)-但在这种情况下，root的类型是Stage，它不会扩展MovieClip，从而导致错误。*

的确，Stage类型同时具有contains和removeChild方法，因此您可以删除强制转换。事实上，Bullet类已经以stageRef的形式引用了stage，所以您可以重用它。尝试将removeSelf()函数更改为：

private function removeSelf():void
{
removeEventListener(Event.ENTER_FRAME, loop);
if (stageRef.contains(this))
stageRef.removeChild(this);
}

*(更多信息：root属性的具体类型因上下文而异。有时它实际上是MovieClip；有时是Bitmap；在您的情况下，如错误所示，它是Stage，但唯一有保证的类型是DisplayObject，这是最低公分母类型，以上类型都继承自它。以下是关于root属性的Adobe文档：http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/display/DisplayObject.html#root)