sub directional_light {
  my ($amb_intensity, $color_r, $direction_r, $intensity, $on) = (@_);
  my @color = @{ $color_r };
  my @direction = @{ $direction_r };
  $on = etf( $on );

  return <<"EOR";
DirectionalLight {
  ambientIntensity $amb_intensity
  color @color
  direction @direction
  intensity $intensity
  on $on
}
EOR
}