message: reverted to previous Ns faceforward approach (Ns and Ng in the same hemisphere) because it eliminates artifacts in most cases
diff: @@ -122,7 +122,7 @@ inline void postIntersect(uniform Model *uniform model,
  if ((flags & DG_NG_FACEFORWARD) == DG_NG_FACEFORWARD)
  if (dot(ray.dir,dg.Ng) >= 0.f) dg.Ng = neg(dg.Ng);
  if ((flags & DG_NS_FACEFORWARD) == DG_NS_FACEFORWARD)
  - if (dot(ray.dir,dg.Ns) >= 0.f) dg.Ns = neg(dg.Ns);
  + if (dot(dg.Ng,dg.Ns) < 0.f) dg.Ns = neg(dg.Ns);
  #undef DG_NG_FACEFORWARD
  #undef DG_NS_FACEFORWARD
  