public Ray GetRay(Vector2 point) {
            Vector3 near = new Vector3(point, 0);
            Vector3 far = new Vector3(point, 1);
            Viewport viewport = new Viewport(0, 0, pbImage.Width, pbImage.Height);
            near = viewport.Unproject(near, camera.Projection, camera.View, Matrix.Identity);
            far = viewport.Unproject(far, camera.Projection, camera.View, Matrix.Identity);

            return new Ray(near, Vector3.Normalize(far - near));
        }