Question

I just began to do some programming in AS3 but there are still some things which aren’t clear to me.

I have project with 3 different files: twinrunner.fla, twinrunner.as and wall.as.

I let the the wall scroll over the screen from right to left. When it hits the player I want to let it recognize it. I tried to accomplish this with the hitTestObject. But unfortunately I only get errors.

twinrunner.as

public class TwinRunner extends MovieClip
{
    private var _timer:Timer;

    public function TwinRunner()
    {
        //Timer initialize
        _timer = new Timer(500, 1);
        _timer.addEventListener(TimerEvent.TIMER_COMPLETE, onUpdateTime);
        _timer.start();

        addEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
    }

    private function onAddedToStage(event:Event):void
    {
        //Add event listeners
        button.addEventListener(MouseEvent.CLICK, onGuessButtonClick);
        addEventListener(Event.ENTER_FRAME, onEnterFrame);
        addEventListener(Event.REMOVED_FROM_STAGE, onRemovedFromStage);
    }

    private function onRemovedFromStage(event:Event):void
    {
        //Remove the onEnterFrame event if
        //this object is removed from the stage
        removeEventListener(Event.ENTER_FRAME, onEnterFrame);
        removeEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
        removeEventListener(Event.REMOVED_FROM_STAGE, onRemovedFromStage);
    }

    private function onGuessButtonClick(event:Event):void
    {
        addChild(new Wall());
    }

    private function onEnterFrame(event:Event):void
    {
    }

    private function onUpdateTime(event:Event):void
    {
        addChild(new Wall());
        _timer.reset();
        _timer.start();
    }

}

wall.as

public class Wall extends MovieClip
{
    private var _vx:int;

    public function Wall()
    {
        addEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
    }

    private function onAddedToStage(event:Event):void
    {
        x = stage.width;
        y = 300;
        _vx = -5;
        stage.addEventListener(KeyboardEvent.KEY_DOWN, onKeyDown);
        addEventListener(Event.REMOVED_FROM_STAGE, onRemovedFromStage)
        addEventListener(Event.ENTER_FRAME, onEnterFrame);
    }
    private function onRemovedFromStage(event:Event):void
    {
        removeEventListener(Event.ENTER_FRAME, onEnterFrame);
        removeEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
        removeEventListener(Event.REMOVED_FROM_STAGE, onRemovedFromStage);
        trace("wall removed");
    }

    private function onKeyDown(event:KeyboardEvent):void
    {
        if (event.keyCode == Keyboard.RIGHT)
        {
        _vx = -20;
        }
    }


    private function onEnterFrame(event:Event):void
    {
        x += _vx;

        if(this.hitTestObject(Player))
        {
            trace("player hit");
        }

        if (x + width / 2 < 0)
        {
            parent.removeChild(this);
        }
    }
}

Every time I try to compile this I get the error 1046:

type not found or not a compile-constant: Player

I guess it is a pretty stupid mistake but I am totally lost and don’t know where to search.

Answer 1

I don’t understand the concept of this game completly so I’ll give you a solution based on what I’ve already understand.

At first I think it’ll be better not to use this, but actually the instance name of the wall.

if(wall.hitTestObject(Player))
{
   trace("player hit");
 }

Also width is nowhere to be found, which means that you have to add (probably you forgot it).

var witdh:Number;

Also hitTestObject is not so precise method for collision. You can calculate the distance between the 2 objects and check if they collide.

This can help you:

http://sierakowski.eu/list-of-tips/39-collision-detection-methods-hittest-and-hittestobject-alternatives.html

http://ughzoid.wordpress.com/2011/06/20/collision-detection-alternatives-to-hittest-and-hittestobject/