[Paraview] CoProcessing needed fields

[Tim Gallagher]

Andy, 

Thanks for the answer. 

What I'm doing doesn't use any writers -- I just want the CoProcessor to output images only. So I don't attach a writer, I just export the state and tell it to "Output Rendering Components". My pipeline looks like: 

Load file -> CellDataToPointData -> Slice 

This results in a RequestDataDescription: 

def RequestDataDescription(datadescription): 
"Callback to populate the request for current timestep" 
if datadescription.GetForceOutput() == True: 
for i in range(datadescription.GetNumberOfInputDescriptions()): 
datadescription.GetInputDescription(i).AllFieldsOn() 
datadescription.GetInputDescription(i).GenerateMeshOn() 
return 

for input_name in simulation_input_map.values(): 
LoadRequestedData(datadescription, input_name) 

This means in my case, there are no fields defined inside the datadescription. So when I try to do the IsFieldNeeded() call in my adaptor, it's always false. If I print the number of fields from GetNumberOfFields(), I get 0. 

So my images when they pop out have no data -- the fields don't exist for them to plot. It's just the slice using the default color for the surface. 

I got it to work by making a new variable just under simulation_input_map: 

simulation_cell_fields_needed = {simulation_input_map['rest_00000.xmf']: ["Temperature [K]", "Density [kg/m^3]"]} 
simulation_point_fields_needed = {simulation_input_map['rest_00000.xmf']: []} 

and putting in RequestDataDescription before the loop that calls LoadRequestedData: 

for input_name in simulation_input_map.values(): 
idd = datadescription.GetInputDescriptionByName(input_name) 
for cell_fields in simulation_cell_fields_needed[input_name]: 
idd.AddCellField(cell_fields) 
for point_fields in simulation_point_fields_needed[input_name]: 
idd.AddPointField(point_fields) 

When I do that, it all works. 

Now, I guess my question is this... Where in the exported state script does it say what fields there are in the data? If I do a trace, when I load a file, I get something like: 

REST_00207_xmf.CellArrays = ['APD_mass_fraction', 'APD_reaction_rate', 'AP_mass_fraction', 'AP_reaction_rate', 'BND_mass_fraction', 'BND\ 
_reaction_rate', 'Density [kg/m^3]', 'HybridSwitch', 'N2_mass_fraction', 'PRD_mass_fraction', 'PRD_reaction_rate', 'Pressure [Pa]', 'Subgrid\ 
kinetic energy [m^2/s^2]', 'Temperature [K]', 'Velocity [m/s]', 'iblanks'] 

and I expected something similar in the exported state script. But I don't see anything like that. 

Following the Fortran API, I call the ClearFieldDataFromGrid which may get rid of the fields that Paraview told it the pipeline needs. 

I could be misunderstanding something, I've never used VTK before this little project attempt. I can certainly send my adaptor code and python script if it helps clarify. 

Thanks again, 

Tim 

----- Original Message -----

From: "Andy Bauer" <andy.bauer at kitware.com> 
To: "tim gallagher" <tim.gallagher at gatech.edu> 
Cc: "ParaView list" <paraview at paraview.org> 
Sent: Thursday, November 8, 2012 6:20:01 PM 
Subject: Re: [Paraview] CoProcessing needed fields 

Hi Tim, 

This should get set in the RequestDataDescription method in the generated Python script. When I first did it I thought we'd easily be able to figure out which fields were needed in order to update all of the required pipelines and/or views. Unfortunately this isn't trivial in VTK so basically what happens is that if a writer or view should output it specifies that all fields should be made available. This is the "datadescription.GetInputDescription(i).AllFieldsOn()" part of the generated python script. 

Answering your final question, this is something that is done automatically in the generated script. 

Andy 


On Wed, Nov 7, 2012 at 2:57 PM, Tim Gallagher < tim.gallagher at gatech.edu > wrote: 


Hi, 

I see in the example code for ParaView/CoProcessing/Adaptors/FortranAdaptors/PhastaAdaptor/PhastaAdaptor.cxx calls like: 

vtkCPInputDataDescription* idd = 
ParaViewCoProcessing::GetCoProcessorData()->GetInputDescriptionByName("input"); 

... 

if(idd->IsFieldNeeded("velocity")) 
{ 
... 

The only way IsFieldNeeded returns true is if that name field was added with AddCellField or AddPointField. 

Where does that happen? My intuition says that the python or C++ processing script (generated by exporting state) would have those calls in it for the datasets that are actually used. In other words, if I set up my view in the GUI and I load my data and put a Slice through it and color by "Velocity", I expected the script from Export State to contain a call to AddCellField("Velocity"). At the very least I expected to see calls to add the fields I chose to load when I loaded my sample file to set up the view. 

So is that something that I need to put in the script on my own after it's exported or did I miss something? If I have to put it there myself, is RequestDataDescription the correct place to put that? 

Thanks, 

Tim 
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