message: Those terms cancel
diff: @@ -360,8 +360,8 @@ public:
  u < reflectance[0],
  reflectance * spectrum<U>(cr * kr),
  (spectrum<U>(1.0) - reflectance) * spectrum<U>(ct * kt)
  - ) / abs(dot(N, wi));
  - return result * (dot(N, wi) / pdf); // TODO: sure?
  + );
  + return result / pdf; // TODO: sure?
  }
  template <typename U>
  