message: Always use `OSP_FB_VARIANCE` to test that it works properly in distrib
diff: @@ -139,6 +139,7 @@ int main(int argc, char **argv) {
  vec3i dimensions = vec3i(-1);
  vec2f valueRange = vec2f(-1);
  size_t nSpheres = 0;
  + float varianceThreshold = 0.0f;
  for (int i = 0; i < argc; ++i) {
  std::string arg = argv[i];
  if (arg == "-f") {
  @@ -154,6 +155,8 @@ int main(int argc, char **argv) {
  valueRange.y = std::atof(argv[++i]);
  } else if (arg == "-spheres") {
  nSpheres = std::atol(argv[++i]);
  + } else if (arg == "-variance") {
  + varianceThreshold = std::atof(argv[++i]);
  }
  }
  if (!volumeFile.empty()) {
  @@ -222,7 +225,6 @@ int main(int argc, char **argv) {
  std::vector<box3f> regions{volume.bounds};
  ospray::cpp::Data regionData(regions.size() * 2, OSP_FLOAT3, regions.data());
  model.set("regions", regionData);
  -
  model.commit();
  Camera camera("perspective");
  @@ -238,11 +240,12 @@ int main(int argc, char **argv) {
  renderer.set("model", model);
  renderer.set("camera", camera);
  renderer.set("bgColor", vec3f(0.02));
  + renderer.set("varianceThreshold", varianceThreshold);
  renderer.commit();
  assert(renderer);
  - FrameBuffer fb(app.fbSize, OSP_FB_SRGBA, OSP_FB_COLOR | OSP_FB_ACCUM);
  - fb.clear(OSP_FB_COLOR | OSP_FB_ACCUM);
  + FrameBuffer fb(app.fbSize, OSP_FB_SRGBA, OSP_FB_COLOR | OSP_FB_ACCUM | OSP_FB_VARIANCE);
  + fb.clear(OSP_FB_COLOR | OSP_FB_ACCUM | OSP_FB_VARIANCE);
  mpicommon::world.barrier();
  @@ -286,7 +289,7 @@ int main(int argc, char **argv) {
  camera.set("up", app.v[2]);
  camera.commit();
  - fb.clear(OSP_FB_COLOR | OSP_FB_ACCUM);
  + fb.clear(OSP_FB_COLOR | OSP_FB_ACCUM | OSP_FB_VARIANCE);
  app.cameraChanged = false;
  }
  renderer.renderFrame(fb, OSP_FB_COLOR);
  @@ -333,7 +336,7 @@ int main(int argc, char **argv) {
  if (app.fbSizeChanged) {
  fb = FrameBuffer(app.fbSize, OSP_FB_SRGBA, OSP_FB_COLOR | OSP_FB_ACCUM);
  - fb.clear(OSP_FB_COLOR | OSP_FB_ACCUM);
  + fb.clear(OSP_FB_COLOR | OSP_FB_ACCUM | OSP_FB_VARIANCE);
  camera.set("aspect", static_cast<float>(app.fbSize.x) / app.fbSize.y);
  camera.commit();
  