VTK/Array Refactoring

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Now that we have N-Way Array Data Structures, it would be ideal if we could use them as attributes in data objects. This will likely involve some tricky work to somehow merge the vtkAbstractArray- and vtkArray- hierarchies.

Recent Work

  • Merged vtkFactoredArrayData / vtkFactoredArrayDataAlgorithm into vtkArrayData / vtkArrayDataAlgorithm.
  • Added vtkArray::GetName() and vtkArray::SetName().
  • vtkDenseArray memory management.
    • vtkDenseArray::MemoryBlock.
    • vtkDenseArray::StaticMemoryBlock.
    • vtkDenseArray::HeapMemoryBlock.
  • vtkSparseICSArray.
    • Changes the way coordinates are stored, one contiguous array of coordinates per dimension, instead of a single contiguous array for all dimensions.
    • Implements value sorting.
    • Could probably replace the current vtkSparseArray implementation.

Proposed Work

  • Provide iterators, memory layout functionality in vtkDenseArray to support in-situ work.
  • Support vtkArray as attributes. Some different approaches:
    1. vtkArray derives from vtkAbstractArray.
      • Worst possible approach, there are methods in vtkAbstractArray (GetVoidPointer()) that are totally incompatible with sparse arrays.
    2. vtkArray and vtkAbstractArray remain apart.
      • vtkFieldData would store vtkArray as a distinct type. Unfortunately, GetArray() is already taken by vtkDataArray.
      • vtkAbstractArray derivatives HAVE-A vtkDenseArray to eliminate duplicate implementations.
    3. vtkAbstractArray derives from vtkArray.
      • Implementing vtkArray in current vtkAbstractArray implementations should be straightforward.
      • vtkFieldData would have to provide methods that return vtkArray. Same problems with GetArray().
      • Implies changes to Get/SetInputArrayToProcess().

Action Items

  • Performance comparisons between vtkDataArray & vtkDenseArray (Tim Shead)
  • Modify vtkAbstractArray to provide access to an (optional) underlying vtkArray (Tim Shead)
  • Modify vtkDataArray to use vtkDenseArray as an implementation (Andy Bauer?)
  • Update vtkFieldData and vtkDataSetAttributes APIs to support vtkArray directly (Andy Bauer?)
  • Deprecate vtkAbstractArray and its derivatives (Brian Wylie)