attr/m49628: use intra lod prediction in top layer

This adoption fixes an issue whereby intra lod prediction is not applied
to the top layer.  By fixing this, intra lod prediction will be used for
the single-layer case.

tmc3/PCCTMC3Common.h

@@ -803,26 +803,15 @@ buildPredictorsFast(
     }
     const int32_t endIndex = indexes.size();
 
-    if (retained.empty()) {
-      for (int32_t i = startIndex; i < endIndex; ++i) {
-        const int32_t index = indexes[i];
-        const int32_t pointIndex = packedVoxel[index].index;
-        indexes[i] = pointIndex;
-        auto& predictor = predictors[--predIndex];
-        assert(predIndex >= 0);
-        pointIndexToPredictorIndex[pointIndex] = predIndex;
-        predictor.init(PCC_UNDEFINED_INDEX);
-      }
-      break;
-    } else {
-      computeNearestNeighbors(
-        pointCloud, packedVoxel, retained, startIndex, endIndex, searchRange2,
-        numberOfNearestNeighborsInPrediction, indexes, predictors,
-        pointIndexToPredictorIndex, predIndex, bBoxes,
-        intraLodPredictionEnabled);
-    }
+    computeNearestNeighbors(
+      pointCloud, packedVoxel, retained, startIndex, endIndex, searchRange2,
+      numberOfNearestNeighborsInPrediction, indexes, predictors,
+      pointIndexToPredictorIndex, predIndex, bBoxes,
+      intraLodPredictionEnabled);
 
-    numberOfPointsPerLevelOfDetail.push_back(retained.size());
+    if (!retained.empty()) {
+      numberOfPointsPerLevelOfDetail.push_back(retained.size());
+    }
     input.resize(0);
     std::swap(retained, input);
   }