code: function _runForPartialViewportFeatures (viewportFeaturesExpressions, renderLayer, featuresIDs) {
      // Reset previous expressions with (possibly 1 partial) features
      viewportFeaturesExpressions.forEach(expr => expr._resetViewportAgg(null, renderLayer));
  
      // Gather all pieces per feature
      const piecesPerFeature = renderLayer.getAllPiecesPerFeature(featuresIDs);
  
      // Run viewportFeatures with the whole set of feature pieces
      viewportFeaturesExpressions.forEach(expr => {
          for (const featureId in piecesPerFeature) {
              expr.accumViewportAgg(piecesPerFeature[featureId]);
          }
      });
  }
docs: Rerun viewportFeatures to improve its results, including all feature pieces in dataframes