message: This won't happen for sure
diff: @@ -95,7 +95,7 @@ inline vector<3, T> cosine_sample_hemisphere(T const& u1, T const& u2)
  auto theta = constants::two_pi<T>() * u2;
  auto x = r * cos(theta);
  auto y = r * sin(theta);
  - auto z = sqrt( max(T(0.0), T(1.0) - u1) );
  + auto z = sqrt(T(1.0) - u1);
  return vector<3, T>(x, y, z);
  }
  