message: Use NaN space skipping for empty areas of unstructured volume bbox
diff: @@ -311,7 +311,7 @@ inline varying float UnstructuredVolume_sample(
  // Cast to the actual Volume subtype.
  UnstructuredVolume *uniform self = (UnstructuredVolume * uniform) _self;
  - float results = 0;
  + float results = floatbits(0xffffffff); /* NaN */
  traverse(self->bvh, _self, intersectAndSampleCell, results, worldCoordinates);
  