message: Add a mirror material if illum 3
diff: @@ -117,6 +117,7 @@ struct renderer : viewer_type
  emissive<float>,
  glass<float>,
  matte<float>,
  + mirror<float>,
  plastic<float>
  >;
  #endif
  @@ -823,6 +824,15 @@ int main(int argc, char** argv)
  ma.kd() = 1.0f;
  cont.emplace_back(ma);
  }
  + else if (mat.illum == 3)
  + {
  + mirror<float> mi;
  + mi.cr() = from_rgb(mat.cs);
  + mi.kr() = 1.0f;
  + mi.ior() = spectrum<float>(0.0f);
  + mi.absorption() = spectrum<float>(0.0f);
  + cont.emplace_back(mi);
  + }
  else if (mat.illum == 4 && mat.transmission > 0.0f)
  {
  glass<float> gl;
  