private void Viewport_CameraChanged(object sender, RoutedEventArgs e)
{
Vector3D cameraPosition = Viewport.Camera.Position.ToVector3D();
cameraPosition.Normalize();
LightsAxisRotationZ.SetValue(AxisAngleRotation3D.AngleProperty, Math.Atan2(cameraPosition.X, -cameraPosition.Y) * (180d / Math.PI) - 45d);
}