message: Nit: missed final step in comment calculation
  The original to_na_matrix code was left as an explanitory comment, but the return value calculation was omitted.
diff: @@ -118,6 +118,7 @@ impl DrawParam {
  // let axis_angle = Vec3::z() * self.rotation;
  // let rotation = Matrix4::new_rotation(axis_angle);
  // let scale = Matrix4::new_nonuniform_scaling(&Vec3::new(self.scale.x, self.scale.y, 1.0));
  + // translate * offset * rotation * scale * offset_inverse
  let cosr = self.rotation.cos();
  let sinr = self.rotation.sin();
  let m00 = cosr * self.scale.x;
  