nape example: laser

package example
{
    import flash.display.DisplayObjectContainer;
    import flash.display.Sprite;
    import flash.filters.GlowFilter;
    import nape.geom.Ray;
    import nape.geom.RayResult;
    import nape.geom.Vec2;
    import nape.phys.Body;
    import nape.phys.BodyType;
    import nape.shape.Circle;

    /**
     * ...
     * @author liu wong
     *
     */

    public class laserExample extends baseExample
    {
        private var laserBody:Body;

        private var laserSprite:Sprite;
        private var points:Array;

        public function laserExample(prnt:DisplayObjectContainer):void
        {
            super(prnt);
        }

        override protected function init():void
        {
            super.init();

            space.gravity.setxy(0, 0);
            space.worldAngularDrag = Math.PI;
            space.worldLinearDrag = 0.9;

            laserSprite = new Sprite();
            laserSprite.filters = [new GlowFilter(0x770000, 1, 4, 4, 4, 3)];
            addChild(laserSprite);

            addWalls();

            addHand();

            laserBody = addCircle(320, 240, 32, (Math.PI / 180) * -0);

            points = new Array();

            var k:int = 10;
            var i:int;

            for (i = 0; i < k; i++)
            {
                addCircle(random(40, 600), random(40, 440), random(16, 32));
                addRectangle(random(40, 600), random(40, 440), random(32, 64), random(32, 64), Math.random() * Math.PI * 2, false);
            }
        }

        override public function free():void
        {
            laserBody.space = null;
            laserBody = null;

            points.length = 0;
            points = null;

            super.free();
        }

        private function doLaser(src:Vec2, dir:Vec2, normal:Vec2, dst:Vec2):Boolean
        {
            var r:Ray = new Ray(src, dir);

            var rr:RayResult = space.rayCast(r);
            if (rr == null)
                return false;

            normal.set(rr.normal.reflect(dir));
            dst.set(r.at(rr.distance * 0.999));

            return true;
        }

        private function doAllLasers():void
        {
            var k:int = 10;
            var i:int;

            var v1:Vec2 = laserBody.position.copy();
            var v2:Vec2 = Vec2.fromPolar(1, laserBody.rotation);
            var v3:Vec2 = new Vec2(0, 0);
            var v4:Vec2 = new Vec2(0, 0);

            points.length = 0;
            points.push(v1.copy());

            for (i = 0; i < k; i++)
            {
                var b:Boolean = doLaser(v1, v2, v3, v4);
                if (b == false)
                    return;

                points.push(v4.copy());

                v1.set(v4);
                v2.set(v3);
            }
        }

        private function updateLaser():void
        {
            doAllLasers();

            laserSprite.graphics.clear();
            laserSprite.graphics.lineStyle(2, 0xff0000);

            var k:int = points.length;
            if (k > 1)
            {
                laserSprite.graphics.moveTo(points[0].x, points[0].y);

                var i:int;
                for (i = 1; i < k; i++)
                {
                    laserSprite.graphics.lineTo(points[i].x, points[i].y);
                }
            }
        }

        override public function update():void
        {
            super.update();

            updateLaser();
        }
    }

}