Question

Basically what I’m trying to do is make a very simple vertical bullet projectile system (bullets move at a consistant pace, bullets can have a hitTestObject applied, etc), but I’m having difficulties putting something together.

At-the-moment my code is:

// define timer
var myTimer:Timer = new Timer(15);
// define array [list]
var list:Array = new Array();

myTimer.addEventListener(TimerEvent.TIMER, timerListener);
myTimer.start();

function timerListener(e:TimerEvent):void
{

    var Create:Bullet = new Bullet();
    addChild(Create);
    // Starting position
    Create.x = 150;
    Create.y = 150;
    // Push into list
    list.push(Create);
}

for (var i:int; i <= 10; i++){
    list[i].x + 10;
    i++;
    if (i > 10){
        i = 0;
    }
}

The problem is I’ve been having all kinds of issues using for/while/etc when it comes to trying to reference list[i].x and having all the objects move at a consistant pace, including #1010 errors.

If anyone knows a better way to do what I’m looking for, or the fix to my current code, it would be much appreciated. 🙂

Answer 1

When you are moving your list of bullets, you need to properly index the list. The reason you are getting #1010 ‘undefined’ errors is because list[i] is not always defined. You should also remove any bullets that have moved off the screen. I used 300 pixels as an arbitrary cut-off point. you should call moveBullets() on a timer, possible on your 15ms timer above.

try this:

function moveBullets():void{
  var target:Bullet;
  for(var i:int=0;i<list.length;i++){
    target = Bullet(list[i]);
    target.x +=10;
    if(target.x > 300){
      removeChild(target);
      list.splice(i,1);
      i--;
    }
  }
}