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Changes in VTK 7.1 {#VTK-7-1-Changes}

This page documents API and behavior changes between VTK 7.0 and VTK 7.1

Pipeline Update Methods

The following methods were deprecated in VTK 7.1:

vtkAlgorithm:

int SetUpdateExtentToWholeExtent(int port);
int SetUpdateExtentToWholeExtent();
void SetUpdateExtent(int port,
                     int piece,int numPieces, int ghostLevel);
void SetUpdateExtent(
  int piece,int numPieces, int ghostLevel);
void SetUpdateExtent(int port, int extent[6]);
void SetUpdateExtent(int extent[6]);

vtkStreamingDemandDrivenPipeline:

int SetUpdateExtentToWholeExtent(int port);
static int SetUpdateExtentToWholeExtent(vtkInformation *);
int SetUpdateExtent(int port, int extent[6]);
int SetUpdateExtent(int port, int x0, int x1, int y0, int y1, int z0, int z1);
static int SetUpdateExtent(vtkInformation *, int extent[6]);
int SetUpdateExtent(int port,
                    int piece, int numPieces, int ghostLevel);
static int SetUpdateExtent(vtkInformation *,
                           int piece, int numPieces, int ghostLevel);
static int SetUpdatePiece(vtkInformation *, int piece);
static int SetUpdateNumberOfPieces(vtkInformation *, int n);
static int SetUpdateGhostLevel(vtkInformation *, int n);
int SetUpdateTimeStep(int port, double time);
static int SetUpdateTimeStep(vtkInformation *, double time);

The following new methods were added:

vtkAlgorithm:

int Update(int port, vtkInformationVector* requests);
int Update(vtkInformation* requests);
int UpdatePiece(int piece, int numPieces, int ghostLevels, const int extents[6]=0);
int UpdateExtent(const int extents[6]);
int UpdateTimeStep(double time,
    int piece=-1, int numPieces=1, int ghostLevels=0, const int extents[6]=0);

vtkStreamingDemandDrivenPipeline:

int Update(int port, vtkInformationVector* requests);

The main reason behind these changes is to make requesting a particular time step or a particular spatial subset (extent or pieces) during an update easier and more predictable. Prior to these changes, the following is the best way to request a subset during update:

vtkNew<vtkRTAnalyticSource> source;
// Set some properties of source here
source->UpdateInformation();
source->SetUpdateExtent(0, 5, 0, 5, 2, 2);
source->Update();

Note that the following will not work:

vtkNew<vtkRTAnalyticSource> source;
// Set some properties of source here
// source->UpdateInformation(); <-- this was commented out
source->SetUpdateExtent(0, 5, 0, 5, 2, 2);
source->Update();

This is because when the output of an algorithm is initialized, all request meta-data stored in its OutputInformation is removed. The initialization of the output happens during the first RequestInformation, which is why UpdateInformation() needs to be called before setting any request values. To make things more complicated, the following will also not work:

vtkNew<vtkRTAnalyticSource> source;
// Set some properties of source here
source->UpdateInformation();
source->SetUpdateExtent(0, 5, 0, 5, 2, 2);
source->Modified();
source->Update();

This is because during RequestInformation, the extent and piece requests are initialized to default values (which is the whole dataset) and RequestInformation is called during update if the algorithm has been modified since the last information update.

This necessary sequence of calls has been mostly tribal knowledge and is very error prone. To simplify pipeline updates with requests, we introduced a new set of methods. With the new API, our example would be:

vtkNew<vtkRTAnalyticSource> source;
int updateExtent[6] = {0, 5, 0, 5, 2, 2};
// Set some properties of source here
source->UpdateExtent(updateExtent);

To ask for a particular time step from a time source, we would do something like this:

vtkNew<vtkExodusIIReader> reader;
// Set properties here
reader->UpdateTimeStep(0.5);
// or
reader->UpdateTimeStep(0.5, 1, 2, 1);

The last call asks for time value 0.5 and the first of two pieces with one ghost level.

The new algorithm also supports directly passing a number of keys to make requests:

typedef vtkStreamingDemandDrivenPipeline vtkSDDP;
vtkNew<vtkRTAnalyticSource> source;
int updateExtent[6] = {0, 5, 0, 5, 2, 2};
vtkNew<vtkInformation> requests;
requests->Set(vtkSDDP::UPDATE_EXTENT(), updateExtent, 6);
reader->Update(requests.GetPointer());

This is equivalent to:

typedef vtkStreamingDemandDrivenPipeline vtkSDDP;
vtkNew<vtkRTAnalyticSource> source;
int updateExtent[6] = {0, 5, 0, 5, 2, 2};
source->UpdateInformation();
source->GetOutputInformation(0)->Set(vtkSDDP::UPDATE_EXTENT(), updateExtent, 6);
reader->Update();

We expect to remove the deprecated methods in VTK 8.0.

Derivatives

VTK has a C/row-major ordering of arrays. The vtkCellDerivatives filter was erroneously outputting second order tensors (i.e. 9 component tuples) in Fortran/column-major ordering. This has been fixed along with the numpy vector_gradient and strain functions. Additionally, vtkTensors was removed as this class was only used by vtkCellDerivatives and was contributing to the confusion.

vtkSMPTools

The following back-ends have been removed:

  • Simple: This is not a production level backend and was only used for debugging purposes.
  • Kaapi: This backend is no longer maintained.

vtkDataArray Refactor, vtkArrayDispatch and Related Tools

The vtkDataArrayTemplate template class has been replaced by vtkAOSDataArrayTemplate to distinguish it from the new vtkSOADataArrayTemplate. The former uses Array-Of-Structs component ordering while the latter uses Struct-Of-Arrays component ordering. These both derive from the new vtkGenericDataArray template class and are an initial implementation of native support for alternate memory layouts in VTK.

To facilitate working with these arrays efficiently, several new tools have been added in this release. They are detailed \ref VTK-7-1-ArrayDispatch "here".

As part of the refactoring effort, several vtkDataArrayTemplate methods were deprecated and replaced with new, const-correct methods with more meaningful names.

The old and new method names are listed below:

  • GetTupleValue is now GetTypedTuple
  • SetTupleValue is now SetTypedTuple
  • InsertTupleValue is now InsertTypedTuple
  • InsertNextTupleValue is now InsertNextTypedTuple
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