我正在制作一个导弹防御类型的游戏，并试图让导弹以随机的角度落下。我还需要子弹图像以我拍摄的角度转动。我对 AS3 中的角度非常陌生，所以我需要一些帮助。
代码：
import spark.components.Image;
public var missiles:Array;
public var bullets:Array;
public var playerLife:Number;
public var targetX:Number;
public var targetY:Number;
public function init():void {
startGame();
}
public function onEnterFrame(e:Event):void {
if(Math.random() <.05 ){
//make a new missle
var newMissile:Image = new Image();
//draw to is
newMissile.source = "assets/missileDown.jpg";
//position it
newMissile.x = Math.random() * stage.stageWidth;
//animate it
newMissile.addEventListener(Event.ENTER_FRAME, onMissileEnterFrame);
//add it to missle array
missiles.push(newMissile);
//add it to the screen
gameGroup.addElement(newMissile);
}
}
public function startGame():void {
//makes new arrays
//gets rid of old arrays
missiles = new Array();
bullets = new Array();
//set player life
playerLife = 5;
//show player life
playerHealth.text = String(playerLife);
//add animation and mouse interation
this.addEventListener(Event.ENTER_FRAME, onEnterFrame);
stage.addEventListener(MouseEvent.CLICK, fireWeapon);
//set game over alpha
gameEnd.alpha = 0;
reset.alpha = 0;
//set game start alpha
playerHealth.alpha = 1;
healthLabel.alpha = 1;
}
//updates the missle
public function onMissileEnterFrame(e:Event):void {
//reference to target
var targetMissile:Image = Image(e.currentTarget);
//move missle down
targetMissile.y += 10;
//if missle has gone too far, remove it and player loses life
if(targetMissile.y > stage.stageHeight) {
playerLife --;
removeMissile(targetMissile);
//show player life
playerHealth.text = String(playerLife);
}
//if player is dead, game over
if(playerLife <= 0) {
gameOver();
}
}
//update bullet
public function onBulletEnterFrame(e:Event):void {
//get reference to bullet
var thisBullet:Bullet = Bullet(e.currentTarget);
//animate towards point..
//calculate difference between current position and desired position
var diffX:Number = thisBullet.targX - thisBullet.x;
var diffY:Number = thisBullet.targY - thisBullet.y;
//move 10% of difference closer
thisBullet.x += diffX * .1;
thisBullet.y += diffY * .1;
//chekc for overlap between bullet and missles
for(var i:Number = 0; i < missiles.length; i++) {
//if they do overlap, remove missle
if( thisBullet.hitTestObject(missiles[i]) ) {
removeMissile(missiles[i]);
removeBullet(thisBullet);
break;
}
}
//if we're 'close enough' to the target position, remove bullet
if(Math.abs(diffX) < 10 && Math.abs(diffY) < 10) {
removeBullet(thisBullet);
}
}
//gets rid of a missle
public function removeMissile(targetMissile:Image):void {
//removes the missle from the missiles array
for(var i:Number = missiles.length - 1; i >= 0; i--) {
if(missiles[i] == targetMissile) {
missiles.splice(i,1);
break;
}
}
//don't animate anymore
targetMissile.removeEventListener(Event.ENTER_FRAME, onMissileEnterFrame);
//remove from stage
gameGroup.removeElement(targetMissile);
}
//removes bullet from stage
public function removeBullet(targetBullet:Bullet):void {
//stop animation
targetBullet.removeEventListener(Event.ENTER_FRAME, onBulletEnterFrame);
//remove from stage
gameGroup.removeElement(targetBullet);
}
//shoot a bullet at the mouse position
public function fireWeapon(e:MouseEvent):void {
//make a new bullet
var newBullet:Bullet = new Bullet();
newBullet.addEventListener(Event.ENTER_FRAME, onBulletEnterFrame);
//position near the earth in the center
var halfStage:Number = stage.stageWidth / 2;
newBullet.x = halfStage;
newBullet.y = 500;
//set target
newBullet.targX = stage.mouseX;
newBullet.targY = stage.mouseY;
//add it to the stage
gameGroup.addElement(newBullet);
}
//you lose
public function gameOver():void {
//remove missles
for(var i:Number = 0; i < missiles.length; i++) {
removeMissile(missiles[i]);
}
//stop interaction
stage.removeEventListener(MouseEvent.CLICK, fireWeapon);
//stop animation
this.removeEventListener(Event.ENTER_FRAME, onEnterFrame);
//set game start alpha
playerHealth.alpha = 0;
healthLabel.alpha = 0;
//set game end alpha
gameEnd.alpha = 1;
reset.alpha = 1;
}
]]>
</fx:Script>