ENH: Add AppendDataSet method

Added method to append a dataset at a given level

Filtering/vtkHierarchicalBoxDataSet.cxx

@@ -223,6 +223,30 @@ void vtkHierarchicalBoxDataSet::SetDataSet(
     }
 }
 
+//------------------------------------------------------------------------------
+void vtkHierarchicalBoxDataSet::AppendDataSet(
+    unsigned int level, vtkUniformGrid* grid )
+{
+  // STEP 0: Resize the number of levels accordingly
+  if( level >= this->GetNumberOfLevels() )
+    {
+      this->SetNumberOfLevels( level+1 );
+    }
+
+  // STEP 1: Insert data at the end
+  vtkMultiPieceDataSet* levelDS =
+      vtkMultiPieceDataSet::SafeDownCast( this->Superclass::GetChild(level));
+  if( levelDS != NULL )
+    {
+      unsigned int idx = levelDS->GetNumberOfPieces();
+      levelDS->SetPiece(idx, grid);
+    }
+  else
+    {
+      vtkErrorMacro( "Multi-piece data-structure is NULL!!!!" );
+    }
+}
+
 //------------------------------------------------------------------------------
 void vtkHierarchicalBoxDataSet::SetMetaData(
     unsigned int level, unsigned int id, const vtkAMRBox &box )

Filtering/vtkHierarchicalBoxDataSet.h

@@ -111,6 +111,11 @@ public:
   // resize the number of levels and the number of datasets accordingly.
   void SetDataSet(unsigned int level, unsigned int id, vtkUniformGrid* dataSet);
 
+  // Description:
+  // Appends the dataset to the given level. This will resize the
+  // number of levels and the number of datasets accordingly.
+  void AppendDataSet(unsigned int level, vtkUniformGrid* dataSet );
+
   // Description:
   // Sets the meta-data object at a given node. This will resize the number
   // of levels and number of datasets acoordingly.