data/src/meshTools/cellClassification/cellClassification.C

/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
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    \\  /    A nd           | Copyright (C) 2011-2026 OpenFOAM Foundation
     \\/     M anipulation  |
-------------------------------------------------------------------------------
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
    (at your option) any later version.

    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.

    You should have received a copy of the GNU General Public License
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.

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

#include "cellClassification.H"
#include "triSurfaceSearch.H"
#include "meshSearch.H"
#include "treeDataFace.H"
#include "cellInfo.H"
#include "polyMesh.H"
#include "FaceCellWave.H"
#include "ListOps.H"
#include "meshTools.H"
#include "cpuTime.H"
#include "triSurface.H"
#include "globalMeshData.H"

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

namespace Foam
{
defineTypeNameAndDebug(cellClassification, 0);
}


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

Foam::label Foam::cellClassification::count
(
    const labelList& elems,
    const label elem
)
{
    label cnt = 0;

    forAll(elems, elemI)
    {
        if (elems[elemI] == elem)
        {
            cnt++;
        }
    }
    return cnt;

}


// Mark all faces that are cut by the surface. Two pass:
// Pass1: mark all mesh edges that intersect surface (quick since triangle
// pierce test).
// Pass2: Check for all point neighbours of these faces whether any of their
// faces are pierced.
Foam::boolList Foam::cellClassification::markFaces
(
    const triSurfaceSearch& search
) const
{
    cpuTime timer;

    boolList cutFace(mesh_.nFaces(), false);

    label nCutFaces = 0;

    // Intersect mesh edges with surface (is fast) and mark all faces that
    // use edge.

    forAll(mesh_.edges(), edgeI)
    {
        if (debug && (edgeI % 10000 == 0))
        {
            Pout<< "Intersecting mesh edge " << edgeI << " with surface"
                << endl;
        }

        const edge& e = mesh_.edges()[edgeI];

        const point& p0 = mesh_.points()[e.start()];
        const point& p1 = mesh_.points()[e.end()];

        pointIndexHit pHit(search.tree().findLineAny(p0, p1));

        if (pHit.hit())
        {
            const labelList& myFaces = mesh_.edgeFaces()[edgeI];

            forAll(myFaces, myFacei)
            {
                label facei = myFaces[myFacei];

                if (!cutFace[facei])
                {
                    cutFace[facei] = true;

                    nCutFaces++;
                }
            }
        }
    }

    if (debug)
    {
        Pout<< "Intersected edges of mesh with surface in = "
            << timer.cpuTimeIncrement() << " s\n" << endl << endl;
    }

    //
    // Construct octree on faces that have not yet been marked as cut
    //

    labelList allFaces(mesh_.nFaces() - nCutFaces);

    label allFacei = 0;

    forAll(cutFace, facei)
    {
        if (!cutFace[facei])
        {
            allFaces[allFacei++] = facei;
        }
    }

    if (debug)
    {
        Pout<< "Testing " << allFacei << " faces for piercing by surface"
            << endl;
    }

    treeBoundBox allBb(mesh_.points());

    // Extend domain slightly (also makes it 3D if was 2D)
    scalar tol = 1e-6 * allBb.avgDim();

    point& bbMin = allBb.min();
    bbMin.x() -= tol;
    bbMin.y() -= tol;
    bbMin.z() -= tol;

    point& bbMax = allBb.max();
    bbMax.x() += 2*tol;
    bbMax.y() += 2*tol;
    bbMax.z() += 2*tol;

    indexedOctree<treeDataFace> faceTree
    (
        treeDataFace(false, mesh_, allFaces),
        allBb,      // overall search domain
        8,          // maxLevel
        10,         // leafsize
        3.0         // duplicity
    );

    const triSurface& surf = search.surface();
    const edgeList& edges = surf.edges();
    const pointField& localPoints = surf.localPoints();

    label nAddFaces = 0;

    forAll(edges, edgeI)
    {
        if (debug && (edgeI % 10000 == 0))
        {
            Pout<< "Intersecting surface edge " << edgeI
                << " with mesh faces" << endl;
        }
        const edge& e = edges[edgeI];

        const point& start = localPoints[e.start()];
        const point& end = localPoints[e.end()];

        vector edgeNormal(end - start);
        const scalar edgeMag = mag(edgeNormal);
        const vector smallVec = 1e-9*edgeNormal;

        edgeNormal /= edgeMag+vSmall;

        // Current start of pierce test
        point pt = start;

        while (true)
        {
            pointIndexHit pHit(faceTree.findLine(pt, end));

            if (!pHit.hit())
            {
                break;
            }
            else
            {
                label facei = faceTree.shapes().faceLabels()[pHit.index()];

                if (!cutFace[facei])
                {
                    cutFace[facei] = true;

                    nAddFaces++;
                }

                // Restart from previous endpoint
                pt = pHit.hitPoint() + smallVec;

                if (((pt-start) & edgeNormal) >= edgeMag)
                {
                    break;
                }
            }
        }
    }

    if (debug)
    {
        Pout<< "Detected an additional " << nAddFaces << " faces cut"
            << endl;

        Pout<< "Intersected edges of surface with mesh faces in = "
            << timer.cpuTimeIncrement() << " s\n" << endl << endl;
    }

    return cutFace;
}


// Determine faces cut by surface and use to divide cells into types. See
// cellInfo. All cells reachable from outsidePts are considered to be of type
// 'outside'
void Foam::cellClassification::markCells
(
    const boolList& piercedFace,
    const List<point>& outsidePts
)
{
    // Use meshwave to partition mesh, starting from outsidePt

    // Construct null; sets type to NOTSET
    List<cellInfo> cellInfoList(mesh_.nCells());

    // Mark cut cells first
    forAll(piercedFace, facei)
    {
        if (piercedFace[facei])
        {
            cellInfoList[mesh_.faceOwner()[facei]] =
                cellInfo(cellClassification::CUT);

            if (mesh_.isInternalFace(facei))
            {
                cellInfoList[mesh_.faceNeighbour()[facei]] =
                    cellInfo(cellClassification::CUT);
            }
        }
    }


    //
    // Mark cells containing outside points as being outside
    //

    // Coarse guess number of faces
    labelHashSet outsideFacesMap(outsidePts.size() * 6 * 2);

    forAll(outsidePts, outsidePtI)
    {
        // Use linear search for points.
        label celli = meshSearch::findCellNoTree(mesh_, outsidePts[outsidePtI]);

        if (returnReduce(celli, maxOp()) == -1)
        {
            FatalErrorInFunction
                << "outsidePoint " << outsidePts[outsidePtI]
                << " is not inside any cell"
                << nl << "It might be on a face or outside the geometry"
                << exit(FatalError);
        }

        if (celli >= 0)
        {
            cellInfoList[celli] = cellInfo(cellClassification::OUTSIDE);

            // Mark faces of celli
            const labelList& myFaces = mesh_.cells()[celli];
            forAll(myFaces, myFacei)
            {
                outsideFacesMap.insert(myFaces[myFacei]);
            }
        }
    }


    //
    // Mark faces to start wave from
    //

    labelList changedFaces(outsideFacesMap.toc());

    List<cellInfo> changedFacesInfo
    (
        changedFaces.size(),
        cellInfo(cellClassification::OUTSIDE)
    );

    List<cellInfo> faceInfoList(mesh().nFaces());
    FaceCellWave<cellInfo> cellInfoCalc
    (
        mesh_,
        changedFaces,                           // Labels of changed faces
        changedFacesInfo,                       // Information on changed faces
        faceInfoList,
        cellInfoList,                           // Information on all cells
        mesh_.globalData().nTotalCells() + 1    // max iterations
    );

    forAll(cellInfoList, celli)
    {
        label t = cellInfoList[celli].type();

        if (t == cellClassification::NOTSET)
        {
            t = cellClassification::INSIDE;
        }
        operator[](celli) = t;
    }
}


void Foam::cellClassification::classifyPoints
(
    const label meshType,
    const labelList& cellType,
    List<pointStatus>& pointSide
) const
{
    pointSide.setSize(mesh_.nPoints());

    forAll(mesh_.pointCells(), pointi)
    {
        const labelList& pCells = mesh_.pointCells()[pointi];

        pointSide[pointi] = UNSET;

        forAll(pCells, i)
        {
            label type = cellType[pCells[i]];

            if (type == meshType)
            {
                if (pointSide[pointi] == UNSET)
                {
                    pointSide[pointi] = MESH;
                }
                else if (pointSide[pointi] == NONMESH)
                {
                    pointSide[pointi] = MIXED;

                    break;
                }
            }
            else
            {
                if (pointSide[pointi] == UNSET)
                {
                    pointSide[pointi] = NONMESH;
                }
                else if (pointSide[pointi] == MESH)
                {
                    pointSide[pointi] = MIXED;

                    break;
                }
            }
        }
    }
}


bool Foam::cellClassification::usesMixedPointsOnly
(
    const List<pointStatus>& pointSide,
    const label celli
) const
{
    const faceList& faces = mesh_.faces();

    const cell& cFaces = mesh_.cells()[celli];

    forAll(cFaces, cFacei)
    {
        const face& f = faces[cFaces[cFacei]];

        forAll(f, fp)
        {
            if (pointSide[f[fp]] != MIXED)
            {
                return false;
            }
        }
    }

    // All points are mixed.
    return true;
}


void Foam::cellClassification::getMeshOutside
(
    const label meshType,
    faceList& outsideFaces,
    labelList& outsideOwner
) const
{
    const labelList& own = mesh_.faceOwner();
    const labelList& nbr = mesh_.faceNeighbour();
    const faceList& faces = mesh_.faces();

    outsideFaces.setSize(mesh_.nFaces());
    outsideOwner.setSize(mesh_.nFaces());
    label outsideI = 0;

    // Get faces on interface between meshType and non-meshType

    for (label facei = 0; facei < mesh_.nInternalFaces(); facei++)
    {
        label ownType = operator[](own[facei]);
        label nbrType = operator[](nbr[facei]);

        if (ownType == meshType && nbrType != meshType)
        {
            outsideFaces[outsideI] = faces[facei];
            outsideOwner[outsideI] = own[facei];    // meshType cell
            outsideI++;
        }
        else if (ownType != meshType && nbrType == meshType)
        {
            outsideFaces[outsideI] = faces[facei];
            outsideOwner[outsideI] = nbr[facei];    // meshType cell
            outsideI++;
        }
    }

    // Get faces on outside of real mesh with cells of meshType.

    for (label facei = mesh_.nInternalFaces(); facei < mesh_.nFaces(); facei++)
    {
        if (operator[](own[facei]) == meshType)
        {
            outsideFaces[outsideI] = faces[facei];
            outsideOwner[outsideI] = own[facei];    // meshType cell
            outsideI++;
        }
    }
    outsideFaces.setSize(outsideI);
    outsideOwner.setSize(outsideI);
}


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

// Construct from mesh and surface and point(s) on outside
Foam::cellClassification::cellClassification
(
    const polyMesh& mesh,
    const triSurfaceSearch& surfQuery,
    const List<point>& outsidePoints
)
:
    labelList(mesh.nCells(), cellClassification::NOTSET),
    mesh_(mesh)
{
    markCells(markFaces(surfQuery), outsidePoints);
}


// Construct from mesh and meshType.
Foam::cellClassification::cellClassification
(
    const polyMesh& mesh,
    const labelList& cellType
)
:
    labelList(cellType),
    mesh_(mesh)
{
    if (mesh_.nCells() != size())
    {
        FatalErrorInFunction
            << "Number of elements of cellType argument is not equal to the"
            << " number of cells" << abort(FatalError);
    }
}


// Copy constructor
Foam::cellClassification::cellClassification(const cellClassification& cType)
:
    labelList(cType),
    mesh_(cType.mesh())
{}


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


// Makes cutCells further than nLayers away from meshType to
// fillType. Returns number of cells changed.
Foam::label Foam::cellClassification::trimCutCells
(
    const label nLayers,
    const label meshType,
    const label fillType
)
{
    // Temporary cell type for growing.
    labelList newCellType(*this);

//    // Split types into outside and rest
//    forAll(*this, celli)
//    {
//        label type = operator[](celli);
//
//        if (type == meshType)
//        {
//            newCellType[celli] = type;
//        }
//        else
//        {
//            newCellType[celli] = fillType;
//        }
//    }

    newCellType = *this;


    // Do point-cell-point walk on newCellType out from meshType cells
    for (label iter = 0; iter < nLayers; iter++)
    {
        // Get status of points: visible from meshType (pointSide == MESH)
        // or fillType/cutCells cells (pointSide == NONMESH) or
        // both (pointSide == MIXED)
        List<pointStatus> pointSide(mesh_.nPoints());
        classifyPoints(meshType, newCellType, pointSide);

        // Grow layer of outside cells
        forAll(pointSide, pointi)
        {
            if (pointSide[pointi] == MIXED)
            {
                // Make cut
                const labelList& pCells = mesh_.pointCells()[pointi];

                forAll(pCells, i)
                {
                    label type = newCellType[pCells[i]];

                    if (type == cellClassification::CUT)
                    {
                        // Found cut cell sharing point with
                        // mesh type cell. Grow.
                        newCellType[pCells[i]] = meshType;
                    }
                }
            }
        }
    }

    // Merge newCellType into *this:
    // - leave meshType cells intact
    // - leave nonMesh cells intact
    // - make cutcells fillType if they were not marked in newCellType

    label nChanged = 0;

    forAll(newCellType, celli)
    {
        if (operator[](celli) == cellClassification::CUT)
        {
            if (newCellType[celli] != meshType)
            {
                // Cell was cutCell but further than nLayers away from
                // meshType. Convert to fillType.
                operator[](celli) = fillType;
                nChanged++;
            }
        }
    }

    return nChanged;
}


// Grow surface by pointNeighbours of type meshType
Foam::label Foam::cellClassification::growSurface
(
    const label meshType,
    const label fillType
)
{
    boolList hasMeshType(mesh_.nPoints(), false);

    // Mark points used by meshType cells

    forAll(mesh_.pointCells(), pointi)
    {
        const labelList& myCells = mesh_.pointCells()[pointi];

        // Check if one of cells has meshType
        forAll(myCells, myCelli)
        {
            label type = operator[](myCells[myCelli]);

            if (type == meshType)
            {
                hasMeshType[pointi] = true;

                break;
            }
        }
    }

    // Change neighbours of marked points

    label nChanged = 0;

    forAll(hasMeshType, pointi)
    {
        if (hasMeshType[pointi])
        {
            const labelList& myCells = mesh_.pointCells()[pointi];

            forAll(myCells, myCelli)
            {
                if (operator[](myCells[myCelli]) != meshType)
                {
                    operator[](myCells[myCelli]) = fillType;

                    nChanged++;
                }
            }
        }
    }
    return nChanged;
}


// Check all points used by cells of meshType for use of at least one point
// which is not on the outside. If all points are on the outside of the mesh
// this would probably result in a flattened cell when projecting the cell
// onto the surface.
Foam::label Foam::cellClassification::fillHangingCells
(
    const label meshType,
    const label fillType,
    const label maxIter
)
{
    label nTotChanged = 0;

    for (label iter = 0; iter < maxIter; iter++)
    {
        label nChanged = 0;

        // Get status of points: visible from meshType or non-meshType cells
        List<pointStatus> pointSide(mesh_.nPoints());
        classifyPoints(meshType, *this, pointSide);

        // Check all cells using mixed point type for whether they use mixed
        // points only. Note: could probably speed this up by counting number
        // of mixed verts per face and mixed faces per cell or something?
        forAll(pointSide, pointi)
        {
            if (pointSide[pointi] == MIXED)
            {
                const labelList& pCells = mesh_.pointCells()[pointi];

                forAll(pCells, i)
                {
                    label celli = pCells[i];

                    if (operator[](celli) == meshType)
                    {
                        if (usesMixedPointsOnly(pointSide, celli))
                        {
                            operator[](celli) = fillType;

                            nChanged++;
                        }
                    }
                }
            }
        }
        nTotChanged += nChanged;

        Pout<< "removeHangingCells : changed " << nChanged
            << " hanging cells" << endl;

        if (nChanged == 0)
        {
            break;
        }
    }

    return nTotChanged;
}


Foam::label Foam::cellClassification::fillRegionEdges
(
    const label meshType,
    const label fillType,
    const label maxIter
)
{
    label nTotChanged = 0;

    for (label iter = 0; iter < maxIter; iter++)
    {
        // Get interface between meshType cells and non-meshType cells as a list
        // of faces and for each face the cell which is the meshType.
        faceList outsideFaces;
        labelList outsideOwner;

        getMeshOutside(meshType, outsideFaces, outsideOwner);

        // Build primitivePatch out of it and check it for problems.
        primitiveFacePatch fp(outsideFaces, mesh_.points());

        const labelListList& edgeFaces = fp.edgeFaces();

        label nChanged = 0;

        // Check all edgeFaces for non-manifoldness

        forAll(edgeFaces, edgeI)
        {
            const labelList& eFaces = edgeFaces[edgeI];

            if (eFaces.size() > 2)
            {
                // patch connected through pinched edge. Remove first face using
                // edge (and not yet changed)

                forAll(eFaces, i)
                {
                    label patchFacei = eFaces[i];

                    label ownerCell = outsideOwner[patchFacei];

                    if (operator[](ownerCell) == meshType)
                    {
                        operator[](ownerCell) = fillType;

                        nChanged++;

                        break;
                    }
                }
            }
        }

        nTotChanged += nChanged;

        Pout<< "fillRegionEdges : changed " << nChanged
            << " cells using multiply connected edges" << endl;

        if (nChanged == 0)
        {
            break;
        }
    }

    return nTotChanged;
}


Foam::label Foam::cellClassification::fillRegionPoints
(
    const label meshType,
    const label fillType,
    const label maxIter
)
{
    label nTotChanged = 0;

    for (label iter = 0; iter < maxIter; iter++)
    {
        // Get interface between meshType cells and non-meshType cells as a list
        // of faces and for each face the cell which is the meshType.
        faceList outsideFaces;
        labelList outsideOwner;

        getMeshOutside(meshType, outsideFaces, outsideOwner);

        // Build primitivePatch out of it and check it for problems.
        primitiveFacePatch fp(outsideFaces, mesh_.points());

        labelHashSet nonManifoldPoints;

        // Check for non-manifold points.
        fp.checkPointManifold(false, &nonManifoldPoints);

        const Map<label>& meshPointMap = fp.meshPointMap();

        label nChanged = 0;

        forAllConstIter(labelHashSet, nonManifoldPoints, iter)
        {
            // Find a face on fp using point and remove it.
            const label patchPointi = meshPointMap[iter.key()];

            const labelList& pFaces = fp.pointFaces()[patchPointi];

            // Remove any face using conflicting point. Does first face which
            // has not yet been done. Could be more intelligent and decide which
            // one would be best to remove.
            forAll(pFaces, i)
            {
                const label patchFacei = pFaces[i];
                const label ownerCell  = outsideOwner[patchFacei];

                if (operator[](ownerCell) == meshType)
                {
                    operator[](ownerCell) = fillType;

                    nChanged++;
                    break;
                }
            }
        }

        nTotChanged += nChanged;

        Pout<< "fillRegionPoints : changed " << nChanged
            << " cells using multiply connected points" << endl;

        if (nChanged == 0)
        {
            break;
        }
    }

    return nTotChanged;
}


void Foam::cellClassification::writeStats(Ostream& os) const
{
    os  << "Cells:" << size() << endl
        << "    notset  : " << count(*this, NOTSET) << endl
        << "    cut     : " << count(*this, CUT) << endl
        << "    inside  : " << count(*this, INSIDE) << endl
        << "    outside : " << count(*this, OUTSIDE) << endl;
}


// * * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * //

void Foam::cellClassification::operator=(const Foam::cellClassification& rhs)
{
    labelList::operator=(rhs);
}


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