let mut forward = track.curve.velocity(0.0).normalize();
        let mut up = Vec3::new(0.0, 1.0, 0.0);
        if up.dot(forward) > 0.9 {
            up = Vec3::new(1.0, 0.0, 0.0);
        }
        let mut right = up.cross(forward);

                &mut forward,
                &mut right,

    fn add_ring(&mut self, t: f32, uv_y: f32) {

    fn add_ring(&mut self, t: f32, forward: &mut Vec3, right: &mut Vec3, uv_y: f32) {

        let forward = self.curve.velocity(t).normalize();
        let mut up = Vec3::new(0.0, 1.0, 0.0);
        if up.dot(forward) > 0.9 {
            up = Vec3::new(1.0, 0.0, 0.0);
        }
        let right = up.cross(forward);

        let up = -right.normalize().cross(*forward);
        *forward = self.curve.velocity(t).normalize();
        *right = up.cross(*forward);

            self.vertices.push(center + right * x + up * y);

            self.vertices.push(center + *right * x + up * y);