[Paraview] Catalyst and adaptor: attaching new fields

[Andy Bauer]

Hi Michel,

You should be able to pass a single field at a time to Catalyst. I'm not
sure where the problem is but my first guess is that maybe you're giving
the same name to all of the fields. What does the code that's calling
addfield() look like?

Note that the Catalyst API uses things like idd->IsFieldNeeded("pressure")
to check if a field is needed by the pipeline. This has been in the API
since nearly the beginning but we've never had a chance to generate Python
scripts which can take advantage of loading only desired fields. This can
potentially save on both execution time and memory usage. This is on my
radar again but I'm not sure when it will get done. You can modify the
Python scripts though to just request the desired field variables in the
RequestDataDescription() method and everything should work as desired. Let
us know if you want to try that out and need help with it.

Cheers,
Andy

On Mon, Oct 26, 2015 at 11:22 AM, Michel Rasquin <
michel.rasquin at colorado.edu> wrote:

> 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
>
>
>
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