directions.C

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/*---------------------------------------------------------------------------*\
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     \\/     M anipulation  |
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    Copyright (C) 2011-2017 OpenFOAM Foundation
    Copyright (C) 2020,2025 OpenCFD Ltd.
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License
    This file is part of OpenFOAM.

    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
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    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.

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\*---------------------------------------------------------------------------*/

#include "directions.H"
#include "polyMesh.H"
#include "twoDPointCorrector.H"
#include "directionInfo.H"
#include "MeshWave.H"
#include "OFstream.H"
#include "meshTools.H"
#include "hexMatcher.H"
#include "globalMeshData.H"
#include "coordinateSystem.H"

// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //

const Foam::Enum
<
    Foam::directions::directionType
>
Foam::directions::directionTypeNames_
({
    { directionType::TAN1, "tan1" },
    { directionType::TAN2, "tan2" },
    { directionType::NORMAL, "normal" },
});


// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //

void Foam::directions::writeOBJ(Ostream& os, const point& pt)
{
    os << "v " << pt.x() << ' ' << pt.y() << ' ' << pt.z() << endl;
}


void Foam::directions::writeOBJ
(
    Ostream& os,
    const point& pt0,
    const point& pt1,
    label& vertI
)
{
    writeOBJ(os, pt0);
    writeOBJ(os, pt1);

    os << "l " << vertI + 1 << ' ' << vertI + 2 << endl;

    vertI += 2;
}


void Foam::directions::writeOBJ
(
    const fileName& fName,
    const primitiveMesh& mesh,
    const vectorField& dirs
)
{
    Pout<< "Writing cell info to " << fName << " as vectors at the cellCentres"
        << endl << endl;

    OFstream xDirStream(fName);

    label vertI = 0;

    forAll(dirs, celli)
    {
        const point& ctr = mesh.cellCentres()[celli];

        // Calculate local length scale
        scalar minDist = GREAT;

        const labelList& nbrs = mesh.cellCells()[celli];

        forAll(nbrs, nbrI)
        {
            minDist = min(minDist, mag(mesh.cellCentres()[nbrs[nbrI]] - ctr));
        }

        scalar scale = 0.5*minDist;

        writeOBJ(xDirStream, ctr, ctr + scale*dirs[celli], vertI);
    }
}


void Foam::directions::check2D
(
    const twoDPointCorrector* correct2DPtr,
    const vector& vec
)
{
    if (correct2DPtr)
    {
        if (mag(correct2DPtr->planeNormal() & vec) > 1e-6)
        {
            FatalErrorInFunction
                << "is not normal to plane defined in dynamicMeshDict."
                << endl
                << "Either make case 3D or adjust vector."
                << exit(FatalError);
        }
    }
}


Foam::vectorField Foam::directions::propagateDirection
(
    const polyMesh& mesh,
    const bool useTopo,
    const polyPatch& pp,
    const vectorField& ppField,
    const vector& defaultDir
)
{
    // Seed all faces on patch
    labelList changedFaces(pp.size());
    List<directionInfo> changedFacesInfo(pp.size());

    if (useTopo)
    {
        forAll(pp, patchFacei)
        {
            label meshFacei = pp.start() + patchFacei;

            label celli = mesh.faceOwner()[meshFacei];

            if (!hexMatcher::test(mesh, celli))
            {
                FatalErrorInFunction
                    << "useHexTopology specified but cell " << celli
                    << " on face " << patchFacei << " of patch " << pp.name()
                    << " is not a hex" << exit(FatalError);
            }

            const vector& cutDir = ppField[patchFacei];

            // Get edge(bundle) on cell most in direction of cutdir
            label edgeI = meshTools::cutDirToEdge(mesh, celli, cutDir);

            // Convert edge into index on face
            label faceIndex =
                directionInfo::edgeToFaceIndex
                (
                    mesh,
                    celli,
                    meshFacei,
                    edgeI
                );

            // Set initial face and direction
            changedFaces[patchFacei] = meshFacei;
            changedFacesInfo[patchFacei] =
                directionInfo
                (
                    faceIndex,
                    cutDir
                );
        }
    }
    else
    {
        forAll(pp, patchFacei)
        {
            changedFaces[patchFacei] = pp.start() + patchFacei;
            changedFacesInfo[patchFacei] =
                directionInfo
                (
                    -2,         // Geometric information only
                    ppField[patchFacei]
                );
        }
    }

    MeshWave<directionInfo> directionCalc
    (
        mesh,
        changedFaces,
        changedFacesInfo,
        mesh.globalData().nTotalCells()+1
    );

    const List<directionInfo>& cellInfo = directionCalc.allCellInfo();

    vectorField dirField(cellInfo.size());

    label nUnset = 0;
    label nGeom = 0;
    label nTopo = 0;

    forAll(cellInfo, celli)
    {
        label index = cellInfo[celli].index();

        if (index == -3)
        {
            // Never visited
            WarningInFunction
                << "Cell " << celli << " never visited to determine "
                << "local coordinate system" << endl
                << "Using direction " << defaultDir << " instead" << endl;

            dirField[celli] = defaultDir;

            nUnset++;
        }
        else if (index == -2)
        {
            // Geometric direction
            dirField[celli] = cellInfo[celli].n();

            nGeom++;
        }
        else if (index == -1)
        {
            FatalErrorInFunction
                << "Illegal index " << index << endl
                << "Value is only allowed on faces" << abort(FatalError);
        }
        else
        {
            // Topological edge cut. Convert into average cut direction.
            dirField[celli] = meshTools::edgeToCutDir(mesh, celli, index);

            nTopo++;
        }
    }

    reduce(nGeom, sumOp<label>());
    reduce(nTopo, sumOp<label>());
    reduce(nUnset, sumOp<label>());

    Info<< "Calculated local coords for " << defaultDir
        << endl
        << "    Geometric cut cells   : " << nGeom << endl
        << "    Topological cut cells : " << nTopo << endl
        << "    Unset cells           : " << nUnset << endl
        << endl;

    return dirField;
}


// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //

Foam::directions::directions
(
    const polyMesh& mesh,
    const dictionary& dict,
    const twoDPointCorrector* correct2DPtr
)
:
    List<vectorField>()
{
    const wordList wantedDirs(dict.get<wordList>("directions"));
    const word coordSystem(dict.get<word>("coordinateSystem"));

    List<vectorField>::resize(wantedDirs.size());

    bool wantNormal = false;
    bool wantTan1 = false;
    bool wantTan2 = false;
    label nDirs = 0;

    if (coordSystem != "fieldBased")
    {
        for (const word& wantedName : wantedDirs)
        {
            directionType wantedDir = directionTypeNames_[wantedName];

            if (wantedDir == NORMAL)
            {
                wantNormal = true;
            }
            else if (wantedDir == TAN1)
            {
                wantTan1 = true;
            }
            else if (wantedDir == TAN2)
            {
                wantTan2 = true;
            }
        }
    }


    if (coordSystem == "global")
    {
        const dictionary& globalDict = dict.subDict("globalCoeffs");

        vector tan1(globalDict.get<vector>("tan1"));
        check2D(correct2DPtr, tan1);

        vector tan2(globalDict.get<vector>("tan2"));
        check2D(correct2DPtr, tan2);

        const vector normal = normalised(tan1 ^ tan2);

        Info<< "Global Coordinate system:" << endl
            << "     normal : " << normal << endl
            << "     tan1   : " << tan1 << endl
            << "     tan2   : " << tan2
            << endl << endl;

        if (wantNormal)
        {
            operator[](nDirs++) = vectorField(1, normal);
        }
        if (wantTan1)
        {
            operator[](nDirs++) = vectorField(1, tan1);
        }
        if (wantTan2)
        {
            operator[](nDirs++) = vectorField(1, tan2);
        }
    }
    else if (coordSystem == "user")
    {
        const dictionary& globalDict = dict.subDict("userCoeffs");

        auto csysPtr(coordinateSystem::New(mesh.thisDb(), globalDict));
        const auto& cs = csysPtr();

        if (wantNormal)
        {
            // 'Normal' is usually e3.
            vectorField& result = operator[](nDirs++);
            result = cs.transform(mesh.cellCentres(), vector(0, 0, 1));
        }
        if (wantTan1)
        {
            vectorField& result = operator[](nDirs++);
            result = cs.transform(mesh.cellCentres(), vector(1, 0, 0));
        }
        if (wantTan2)
        {
            vectorField& result = operator[](nDirs++);
            result = cs.transform(mesh.cellCentres(), vector(0, 1, 0));
        }
    }
    else if (coordSystem == "patchLocal")
    {
        const dictionary& patchDict = dict.subDict("patchLocalCoeffs");

        const word patchName(patchDict.get<word>("patch"));

        const label patchi = mesh.boundaryMesh().findPatchID(patchName);

        if (patchi == -1)
        {
            FatalErrorInFunction
                << "Cannot find patch "
                << patchName
                << exit(FatalError);
        }

        // Take zeroth face on patch
        const polyPatch& pp = mesh.boundaryMesh()[patchi];

        vector tan1(patchDict.get<vector>("tan1"));

        const vector& n0 = pp.faceNormals()[0];

        if (correct2DPtr)
        {
            tan1 = correct2DPtr->planeNormal() ^ n0;

            WarningInFunction
                << "Discarding user specified tan1 since 2D case." << endl
                << "Recalculated tan1 from face normal and planeNormal as "
                << tan1 << endl << endl;
        }

        const bool useTopo(dict.get<bool>("useHexTopology"));

        vectorField normalDirs;
        vectorField tan1Dirs;

        if (wantNormal || wantTan2)
        {
            normalDirs =
                propagateDirection
                (
                    mesh,
                    useTopo,
                    pp,
                    pp.faceNormals(),
                    n0
                );

            if (wantNormal)
            {
                this->operator[](nDirs++) = normalDirs;
            }
        }

        if (wantTan1 || wantTan2)
        {
            tan1Dirs =
                propagateDirection
                (
                    mesh,
                    useTopo,
                    pp,
                    vectorField(pp.size(), tan1),
                    tan1
                );


            if (wantTan1)
            {
                this->operator[](nDirs++) = tan1Dirs;
            }
        }
        if (wantTan2)
        {
            tmp<vectorField> tan2Dirs = normalDirs ^ tan1Dirs;

            this->operator[](nDirs++) = tan2Dirs;
        }
    }
    else if (coordSystem == "fieldBased")
    {
        forAll(wantedDirs, i)
        {
            operator[](nDirs++) =
                vectorIOField
                (
                    IOobject
                    (
                        mesh.instance()/wantedDirs[i],
                        mesh,
                        IOobject::MUST_READ,
                        IOobject::NO_WRITE
                    )
                );
        }
    }
    else
    {
        FatalErrorInFunction
            << "Unknown coordinate system "
            << coordSystem << endl
            << "Known types are global, patchLocal and fieldBased"
            << exit(FatalError);
    }
}


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