bend line 90 degrees at a point where another movieclip intersects with it in actionscript 3

Question

Essentially, I'm making a game in Flash CS6 where a light source is projected onto the screen. You get a mirror that you can drag around. When the mirror touches the light, however, it should bounce off it and end up 90 degrees offset after it hit the mirror.
I don't have enough reputation to post pictures, but here's a link to an explanation of the problem: http://raphaelhennessy.com/misc/explanation.png
If you can help me solve this I would be really happy.

Thanks in advance,
-Raph

Answer 1

This is an extremely quick and dirty example to get the ball rolling. There are many issues with this code, so I suggest you use it only as a jumping off point. Details are commented within the code.

package 
{
    import flash.display.Sprite;
    import flash.events.Event;
    import flash.events.MouseEvent;

    public class MirrorTest extends Sprite 
    {

        private var _mirror:Sprite;
        private var _line:Sprite;

        public function MirrorTest() 
        {
            super();

            // create the line clip
            _line = addChild(new Sprite()) as Sprite;
            _line.graphics.clear();
            _line.graphics.lineStyle(3, 0xFF0000);
            _line.graphics.moveTo(0, 0);
            _line.graphics.lineTo(500, 0); // starting it off at an arbitrary width
            _line.y = 100; // positioning line so that we can see when it bends upwards

            // create the mirror clip
            _mirror = addChild(new Sprite()) as Sprite;

            // draw a square and rotate it so we have a diamond shape
            _mirror.graphics.beginFill(0);
            _mirror.graphics.drawRect(-20, -20, 40, 40);
            _mirror.graphics.endFill();
            _mirror.rotation = 45;
            _mirror.x = _mirror.y = 200; // position the mirror away from the line

            // add even listeners to trigger dragging/dropping
            _mirror.addEventListener(MouseEvent.MOUSE_DOWN, dragMirror);
            _mirror.addEventListener(MouseEvent.MOUSE_UP, dropMirror);

        }

        private function dragMirror($event:MouseEvent):void 
        {
            // start dragging the mirror. 
            _mirror.startDrag(true);
            // add the ENTER_FRAME listener so that we can check for colision as the mirror is being moved around
            addEventListener(Event.ENTER_FRAME, onTick);
        }

        private function dropMirror($event:MouseEvent):void 
        {
            // stop dragging the mirror
            _mirror.stopDrag();
            // remove the ENTER_FRAME listener so we don't waste cycles checking for collision when the mirror is not being moved around
            removeEventListener(Event.ENTER_FRAME, onTick);
        }

        private function onTick($event:Event):void 
        {
            // check to see if the mirror has collided with the line
            if (_mirror.hitTestObject(_line))
            {
                // if so, redraw the line as a right-angle, using the mirror's position as the "collision point"
                _line.graphics.clear();
                _line.graphics.lineStyle(3, 0xFF0000);
                _line.graphics.moveTo(0, 0);
                _line.graphics.lineTo(_mirror.x - _mirror.width * .5, 0);
                _line.graphics.lineTo(_mirror.x - _mirror.width * .5, -100);
            }
            else
            {
                // if not, redraw the original line
                _line.graphics.clear();
                _line.graphics.lineStyle(3, 0xFF0000);
                _line.graphics.moveTo(0, 0);
                _line.graphics.lineTo(500, 0);
            }

        }

    }

}