[Paraview] Catalyst and adaptor: attaching new fields

[Michel Rasquin]

Hi everyone,

I am trying to add some fields to a vtkCPAdaptorAPI object for coprocessing with Catalyst.
I rely for that purpose on the successful implementation of the Phasta adaptor provided along with ParaView.
See ParaView-v4.4.0-source/CoProcessing/Adaptors/PhastaAdaptor/PhastaAdaptor.cxx.
After the initialization of the coprocessing objects and the generation of the grid, the current implementation to add fields in the phasta adaptor relies on the following function: 

void addfields(… double* dofArray, double* vortArray, double * otherFieldOfInterest … )
{
  vtkCPInputDataDescription* idd = vtkCPAdaptorAPI::GetCoProcessorData()->GetInputDescriptionByName("input”);
  vtkUnstructuredGrid* UnstructuredGrid = vtkUnstructuredGrid::SafeDownCast(idd->GetGrid());
  if(!UnstructuredGrid) {
    vtkGenericWarningMacro("No unstructured grid to attach field data to.");
    return;
  } 

  // now add numerical field data
  //velocity
  vtkIdType NumberOfNodes = UnstructuredGrid->GetNumberOfPoints();
  if(idd->IsFieldNeeded("velocity"))
  {
    vtkDoubleArray* velocity = vtkDoubleArray::New();
    velocity->SetName("velocity");
    velocity->SetNumberOfComponents(3);
    velocity->SetNumberOfTuples(NumberOfNodes);
    for (vtkIdType idx=0; idx<NumberOfNodes; idx++) {
      velocity->SetTuple3(idx, dofArray[idx],
                          dofArray[idx+ *nshg],
                          dofArray[idx+ *nshg*2]);
    }
    UnstructuredGrid->GetPointData()->AddArray(velocity);
    velocity->Delete();
  }

  if(idd->IsFieldNeeded(“vorticity"))
  {
    vtkDoubleArray* vorticity = vtkDoubleArray::New();
    velocity->SetName(“vorticity");
    velocity->SetNumberOfComponents(3);
    velocity->SetNumberOfTuples(NumberOfNodes);
    for (vtkIdType idx=0; idx<NumberOfNodes; idx++) {
      velocity->SetTuple3(idx, vortArray[idx],
                          vortArray[idx+ *nshg],
                          vortArray[idx+ *nshg*2]);
    }
    UnstructuredGrid->GetPointData()->AddArray(vorticity);
    vorticity->Delete();
    }

  // etc for any the other fields of interest for Catalyst
}

Currently, all the fields requested for coprocessing needs to be attached in this function at the same time, using the same pointer to vtkUnstructuredGrid resulting from the SafeDownCast mentioned above. However, I need a more flexible implementation so that I can call addfield (with no “s”) as many times as needed and attach a single field to the vtkCPAdaptorAPI object each time this function is called.

Concretely, my first implementation is simply the following:

void addfield(std::string fieldName, int* NumberOfComp, double* fieldArray)
{
  vtkCPInputDataDescription* idd = vtkCPAdaptorAPI::GetCoProcessorData()->GetInputDescriptionByName("input");
  vtkUnstructuredGrid* UnstructuredGrid = vtkUnstructuredGrid::SafeDownCast(idd->GetGrid());
  if(!UnstructuredGrid) {
    vtkGenericWarningMacro("No unstructured grid to attach field data to.");
    return;
  }

  // Get number of nodes
  vtkIdType NumberOfNodes = UnstructuredGrid->GetNumberOfPoints();

  // Add field
  if(idd->IsFieldNeeded(fieldName.c_str())) {
    vtkDoubleArray* dataArray = vtkDoubleArray::New();
    dataArray->SetName(fieldName.c_str());
    dataArray->SetNumberOfComponents(*NumberOfComp);
    dataArray->SetNumberOfTuples(NumberOfNodes);
    // fill in dataArray from fieldArray, NumberOfNodes and NumberOfComp
    …
    UnstructuredGrid->GetPointData()->AddArray(dataArray);
    dataArray->Delete();
  }
}

The problem is that only the last field passed to this new addfield() function can be actually used by Catalyst for coprocessing. 
Indeed, it appears that all other fields previously passed to addfield() cannot be retrieved from the vtkCPAdaptorAPI object. 
Consequently, any filter in the Catalyst pipeline that relies on the N-1 first fields (out of N in total) passed to addfields() will be ignored because relevant data is missing.

I suspect the issue is in one of the first two lines of the addfield() function, namely

  vtkCPInputDataDescription* idd = vtkCPAdaptorAPI::GetCoProcessorData()->GetInputDescriptionByName("input");
  vtkUnstructuredGrid* UnstructuredGrid = vtkUnstructuredGrid::SafeDownCast(idd->GetGrid());

Could you please let me know if it is possible to pass one single field at a time to the Catalyst adaptor from different locations of the code, or if all the fields must be passed in one shot?

Thank you for your help.

Best regards,

Michel