Simple Sprite subclass with a rectangular mask in stage coordinates

ClippedSprite.as

package starling.extensions
{
    import flash.display3D.Context3D;
    import flash.geom.Point;
    import flash.geom.Rectangle;

    import starling.core.RenderSupport;
    import starling.core.Starling;
    import starling.display.DisplayObject;
    import starling.display.Sprite;
    import starling.errors.MissingContextError;

    public class ClippedSprite extends Sprite
    {
        private var mClipRect:Rectangle;

        public override function render(support:RenderSupport, alpha:Number):void
        {
            if (mClipRect == null) super.render(support, alpha);
            else
            {
                var context:Context3D = Starling.context;
                if (context == null) throw new MissingContextError();

                support.finishQuadBatch();
                context.setScissorRectangle(mClipRect);

                super.render(support, alpha);

                support.finishQuadBatch();
                context.setScissorRectangle(null);
            }
        }

        public override function hitTest(localPoint:Point, forTouch:Boolean=false):DisplayObject
        {
            if (mClipRect == null) return super.hitTest(localPoint, forTouch);

            // on a touch test, invisible or untouchable objects cause the test to fail
            if (forTouch && (!visible || !touchable)) return null;

            var scale:Number = Starling.current.contentScaleFactor;
            var pointX:Number = ((parent ? parent.x : 0) + localPoint.x) * scale;
            var pointY:Number = ((parent ? parent.y : 0) + localPoint.y) * scale;

            if (mClipRect.contains(pointX, pointY))
                return super.hitTest(localPoint, forTouch);
            else
                return null;
        }

        public function get clipRect():Rectangle
        {
            var scale:Number = Starling.current.contentScaleFactor;
            return new Rectangle(mClipRect.x     / scale, mClipRect.y      / scale,
                                 mClipRect.width / scale, mClipRect.height / scale);
        }

        public function set clipRect(value:Rectangle):void
        {
            var scale:Number = Starling.current.contentScaleFactor;
            
            if (mClipRect == null) mClipRect = new Rectangle();
			
            mClipRect.x = scale * value.x;
            mClipRect.y = scale * value.y;
            mClipRect.width  = scale * value.width;
            mClipRect.height = scale * value.height;
        }
    }
}