/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v1912                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/

cellZoneID
{
    type    coded;
    libs    (utilityFunctionObjects);
    name    cellZoneID;

    executeControl  writeTime;

    localCode
    #{
        static const word fieldName("cellZoneID");

        // Create and populate a "cellZoneID" volScalarField for cellZones.
        // Return nullptr if there are not any such zones.
        //
        // Could be improved for mesh motion etc
        // but is fairly low overhead anyhow
        volScalarField* getZoneField(const fvMesh& mesh)
        {
            volScalarField* volZonePtr =
                mesh.getObjectPtr<volScalarField>(fieldName);

            const cellZoneMesh& zones = mesh.cellZones();

            if (!zones.empty())
            {
                if (!volZonePtr)
                {
                    volZonePtr = &regIOobject::store
                    (
                        volScalarField::New
                        (
                            fieldName,
                            mesh,
                            dimless,
                            zeroGradientFvPatchField<scalar>::typeName
                        )
                    );

                    Info<< "Creating " << fieldName
                        << " field for postProcessing" << nl;
                }
            }
            else
            {
                Info<< "No cellZones - not creating " << fieldName
                    << " field for postProcessing" << nl;
            }

            if (volZonePtr)
            {
                // Copy zone id as scalar.
                // For consistency, do this whenever the volField exists,
                // even if there are no zones.

                auto& field = *volZonePtr;

                auto& internal = field.primitiveFieldRef();
                internal = scalar(-1);

                for (const cellZone& zn : zones)
                {
                    UIndirectList<scalar>(internal, zn) = scalar(zn.index());
                }

                field.correctBoundaryConditions();
            }

            return volZonePtr;
        }
    #};

    codeExecute
    #{
        // Don't need the return value, just the contents on the registry.
        (void) getZoneField(mesh());
    #};
}


plane
{
    type    surfaces;
    libs    (sampling);

    writeControl    writeTime;

    surfaceFormat   vtk;
    fields          ( cellZoneID );

    surfaces
    (
        zNormal
        {
            type            cuttingPlane;
            planeType       pointAndNormal;
            pointAndNormalDict
            {
                point   (0 0 0);
                normal  (0 0 1);
            }
            interpolate     false;
        }
    );
}


// ************************************************************************* //