message: add sampling rate to structured volume tutorial
diff: @@ -85,6 +85,7 @@ int main(int argc, const char **argv)
  auto instance = ospNewVolumeInstance(volume);
  ospSetObject(instance, "transferFunction", tfn);
  + ospSet1f(instance, "samplingRate", 0.5f);
  ospCommit(instance);
  ospAddVolumeInstance(world, instance);
  @@ -190,9 +191,17 @@ int main(int argc, const char **argv)
  ImGui::Separator();
  ImGui::NewLine();
  + static float samplingRate = 0.5f;
  + if (ImGui::SliderFloat( "sampling rate", &samplingRate, 1e-3f, 4.f)) {
  + commitWorld = true;
  + ospSet1f(instance, "samplingRate", samplingRate);
  + glfwOSPRayWindow->addObjectToCommit(instance);
  + }
  +
  if (ImGui::SliderFloat(
  "iso value", &isoValue, voxelRange.lower, voxelRange.upper)) {
  setIsoValue(isoGeometry, isoValue);
  + commitWorld = true;
  glfwOSPRayWindow->addObjectToCommit(isoGeometry);
  glfwOSPRayWindow->addObjectToCommit(isoInstance);
  }
  