/// <summary>
        /// Lets the game respond to player input. Unlike the Update method,
        /// this will only be called when the gameplay screen is active.
        /// </summary>
        public override void HandleInput(InputState input)
        {
            //is an object being grabbed?
            if(input.Mouse.IsNewLeftMouseClick)
            {
                int count = 0;
                float mx = Camera1.Relative2Dto3D(input.Mouse.Position).X;
                float my = Camera1.Relative2Dto3D(input.Mouse.Position).Y;
                foreach (var piece in Level.Pieces)
                {
                    float oRadius = piece.ObjectModel.Meshes[0].BoundingSphere.Radius;

                    if(mx < piece.Position.X + oRadius
                        && mx > piece.Position.X - oRadius
                        && my < piece.Position.Y + oRadius
                        && my > piece.Position.Y - oRadius)
                    {
                        ++count;
                        objectGrabbed = piece;
                    }
                }
                DisplayedMessages["levelEditor"] = "clicking on " + count + " number of objects. @ cur pos: "
                                                    + mx + ", " + my;
            }

            //is an object being released?
            if(input.Mouse.IsNewLeftMouseRelease)
                objectGrabbed = null;

            //stick the object to the cursor if it's currently grabbed.
            if(objectGrabbed != null && input.Mouse.LeftMouseDown)
            {
                objectGrabbed.Position = input.Mouse.Position3DSpace;
            }
        }
        public void RemoveObjectFromGame(VisualObject3D obj)
        {
            if (obj is isCollidable)
                GameScreen.Collisions.Collidables.Remove((isCollidable)obj);

            if (obj is hasPosition2D)
                GameScreen.ObjectsToBeWrapped.Remove((hasPosition2D)obj);

            GameScreen.Level.Pieces.Remove(obj);
        }