feature: propagate field attribute from input

[npillardou]

This PR adds the potential opportunity to propagate the attribute field to the ouput pvd results.

By default, this option is ignored but optionnally added such as:

<VTK 
  name="vtkOutput"
  plotFileRoot="faultModel"
  fieldNames="{ attribute }" />

[rrsettgast]

@npillardou Can you describe the benefit to this? You want to be able to visualize the "attribute" in the output? Is that "attribute" not already in the output? Things like initial stress/pore pressure?

[alexbenedicto]

@rrsettgast The goal is to not lose information that was given in input such as:

• GLOBAL_IDS_CELLS and GLOBAL_IDS_POINTS.
• any CellData/PointData array used to tag cells/points.

Currently, you cannot easily compare an input .vtu with the output .vtu given by GEOS. All the indexes of the cells and points are reconstructed by GEOS. There is no easy mapping solution other than using 3D coordinates.

EDIT1:

Ok I thought this would also work with any property given in fieldNames like fieldNames="{ my_property1, my_property2... }" but apparently it is not the case. Only works if your mesh has a property called "attribute" and you just want this one in output.

This would also be great to have for any property, not just "attribute".

EDIT2:

I cannot make it work when using "attribute". The "attribute" does not exist in the output.

[jafranc]

Ok I thought this would also work with any property given in fieldNames like fieldNames="{ my_property1, my_property2... }" but apparently it is not the case. Only works if your mesh has a property called "attribute" and you just want this one in output.

This would also be great to have for any property, not just "attribute".

@alexbenedicto IIRC localToGlobal maps are in the Outputs, so mapping cells should be possible from here.
See GEOS-DEV/geosPythonPackages#193 for application