message: Use power heuristic
diff: @@ -115,7 +115,7 @@ struct kernel
  S mis_weight = select(
  bounce > 0 && num_lights > 0 && !last_specular,
  - balance_heuristic(brdf_pdf, light_pdf / static_cast<float>(num_lights)),
  + power_heuristic(brdf_pdf, light_pdf / static_cast<float>(num_lights)),
  S(1.0)
  );
  @@ -165,7 +165,7 @@ struct kernel
  auto solid_angle = (ldotln * ls.area) / (ld * ld);
  auto light_pdf = S(1.0) / solid_angle;
  - S mis_weight = balance_heuristic(light_pdf / static_cast<float>(num_lights), brdf_pdf);
  + S mis_weight = power_heuristic(light_pdf / static_cast<float>(num_lights), brdf_pdf);
  intensity += select(
  active_rays && !lhr.hit && ldotn > S(0.0) && ldotln > S(0.0),
  