data/applications/utilities/surface/surfaceSubset/surfaceSubset.C

/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    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/>.

Application
    surfaceSubset

Description
    A surface analysis tool which sub-sets the triSurface
    to choose only a part of interest. Based on subsetMesh.

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

#include "triSurface.H"
#include "triSurfaceSearch.H"
#include "argList.H"
#include "OFstream.H"
#include "IFstream.H"
#include "Switch.H"
#include "IOdictionary.H"
#include "boundBox.H"
#include "indexedOctree.H"
#include "treeDataTriSurface.H"
#include "randomGenerator.H"
#include "volumeType.H"
#include "plane.H"

using namespace Foam;

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

int main(int argc, char *argv[])
{
    #include "removeCaseOptions.H"

    argList::validArgs.append("surface file");
    argList::validArgs.append("output surface file");
    argList::validArgs.append("surfaceSubsetDict");
    argList args(argc, argv);

    Info<< "Reading dictionary " << args[3] << " ..." << endl;
    IFstream dictFile(args[3]);
    dictionary meshSubsetDict(dictFile);

    Info<< "Reading surface " << args[1] << " ..." << endl;
    triSurface surf1(args[1]);

    const fileName outFileName = args[2];


    Info<< "Original:" << endl;
    surf1.writeStats(Info);
    Info<< endl;


    labelList markedPoints
    (
        meshSubsetDict.lookup("localPoints")
    );

    labelList markedEdges
    (
        meshSubsetDict.lookup("edges")
    );

    labelList markedFaces
    (
        meshSubsetDict.lookup("faces")
    );

    pointField markedZone
    (
        meshSubsetDict.lookup("zone")
    );

    if (markedZone.size() && markedZone.size() != 2)
    {
        FatalErrorInFunction
            << "zone specification should be two points, min and max of "
            << "the boundingbox" << endl
            << "zone:" << markedZone
            << exit(FatalError);
    }

    Switch addFaceNeighbours
    (
        meshSubsetDict.lookup("addFaceNeighbours")
    );

    const bool invertSelection =
        meshSubsetDict.lookupOrDefault("invertSelection", false);

    // Mark the cells for the subset

    // Faces to subset
    boolList facesToSubset(surf1.size(), false);


    //
    // pick up faces connected to "localPoints"
    //

    if (markedPoints.size())
    {
        Info<< "Found " << markedPoints.size() << " marked point(s)." << endl;

        // pick up cells sharing the point

        forAll(markedPoints, pointi)
        {
            if
            (
                markedPoints[pointi] < 0
             || markedPoints[pointi] >= surf1.nPoints()
            )
            {
                FatalErrorInFunction
                    << "localPoint label " << markedPoints[pointi]
                    << "out of range."
                    << " The mesh has got "
                    << surf1.nPoints() << " localPoints."
                    << exit(FatalError);
            }

            const labelList& curFaces =
                surf1.pointFaces()[markedPoints[pointi]];

            forAll(curFaces, i)
            {
                facesToSubset[curFaces[i]] =  true;
            }
        }
    }



    //
    // pick up faces connected to "edges"
    //

    if (markedEdges.size())
    {
        Info<< "Found " << markedEdges.size() << " marked edge(s)." << endl;

        // pick up cells sharing the edge

        forAll(markedEdges, edgeI)
        {
            if
            (
                markedEdges[edgeI] < 0
             || markedEdges[edgeI] >= surf1.nEdges()
            )
            {
                FatalErrorInFunction
                    << "edge label " << markedEdges[edgeI]
                    << "out of range."
                    << " The mesh has got "
                    << surf1.nEdges() << " edges."
                    << exit(FatalError);
            }

            const labelList& curFaces = surf1.edgeFaces()[markedEdges[edgeI]];

            forAll(curFaces, i)
            {
                facesToSubset[curFaces[i]] =  true;
            }
        }
    }


    //
    // pick up faces with centre inside "zone"
    //

    if (markedZone.size() == 2)
    {
        const point& min = markedZone[0];
        const point& max = markedZone[1];

        Info<< "Using zone min:" << min << " max:" << max << endl;

        forAll(surf1, facei)
        {
            const point centre = surf1[facei].centre(surf1.points());

            if
            (
                (centre.x() >= min.x())
             && (centre.y() >= min.y())
             && (centre.z() >= min.z())
             && (centre.x() <= max.x())
             && (centre.y() <= max.y())
             && (centre.z() <= max.z())
            )
            {
                facesToSubset[facei] = true;
            }
        }
    }


    //
    // pick up faces on certain side of surface
    //

    if (meshSubsetDict.found("surface"))
    {
        const dictionary& surfDict = meshSubsetDict.subDict("surface");

        fileName surfName(surfDict.lookup("name"));

        Switch outside(surfDict.lookup("outside"));

        if (outside)
        {
            Info<< "Selecting all triangles with centre outside surface "
                << surfName << endl;
        }
        else
        {
            Info<< "Selecting all triangles with centre inside surface "
                << surfName << endl;
        }

        // Read surface to select on
        triSurface selectSurf(surfName);

        triSurfaceSearch searchSelectSurf
        (
            selectSurf,
            indexedOctree<treeDataTriSurface>::perturbTol(),
            8
        );

        const indexedOctree<treeDataTriSurface>& selectTree =
            searchSelectSurf.tree();

        // Check if face (centre) is in outside or inside.
        forAll(facesToSubset, facei)
        {
            if (!facesToSubset[facei])
            {
                const point fc(surf1[facei].centre(surf1.points()));

                volumeType t = selectTree.getVolumeType(fc);

                if
                (
                    outside
                  ? (t == volumeType::outside)
                  : (t == volumeType::inside)
                )
                {
                    facesToSubset[facei] = true;
                }
            }
        }
    }


    if (meshSubsetDict.found("plane"))
    {
        const dictionary& planeDict = meshSubsetDict.subDict("plane");

        const plane pl(planeDict);
        const scalar distance(planeDict.lookup<scalar>("distance"));
        const scalar cosAngle(planeDict.lookup<scalar>("cosAngle"));

        // Select all triangles that are close to the plane and
        // whose normal aligns with the plane as well.

        forAll(surf1.faceCentres(), facei)
        {
            const point& fc = surf1.faceCentres()[facei];
            const point& nf = surf1.faceNormals()[facei];

            if (pl.distance(fc) < distance && mag(pl.normal() & nf) > cosAngle)
            {
                facesToSubset[facei] = true;
            }
        }
    }



    //
    // pick up specified "faces"
    //

    // Number of additional faces picked up because of addFaceNeighbours
    label nFaceNeighbours = 0;

    if (markedFaces.size())
    {
        Info<< "Found " << markedFaces.size() << " marked face(s)." << endl;

        // Check and mark faces to pick up
        forAll(markedFaces, facei)
        {
            if
            (
                markedFaces[facei] < 0
             || markedFaces[facei] >= surf1.size()
            )
            {
                FatalErrorInFunction
                    << "Face label " << markedFaces[facei] << "out of range."
                    << " The mesh has got "
                    << surf1.size() << " faces."
                    << exit(FatalError);
            }

            // Mark the face
            facesToSubset[markedFaces[facei]] = true;

            // mark its neighbours if requested
            if (addFaceNeighbours)
            {
                const labelList& curFaces =
                    surf1.faceFaces()[markedFaces[facei]];

                forAll(curFaces, i)
                {
                    label facei = curFaces[i];

                    if (!facesToSubset[facei])
                    {
                        facesToSubset[facei] =  true;
                        nFaceNeighbours++;
                    }
                }
            }
        }
    }

    if (addFaceNeighbours)
    {
        Info<< "Added " << nFaceNeighbours
            << " faces because of addFaceNeighbours" << endl;
    }


    if (invertSelection)
    {
        Info<< "Inverting selection." << endl;

        forAll(facesToSubset, i)
        {
            facesToSubset[i] = facesToSubset[i] ? false : true;
        }
    }


    // Create subsetted surface
    labelList pointMap;
    labelList faceMap;
    triSurface surf2
    (
        surf1.subsetMesh(facesToSubset, pointMap, faceMap)
    );

    Info<< "Subset:" << endl;
    surf2.writeStats(Info);
    Info<< endl;

    Info<< "Writing surface to " << outFileName << endl;

    surf2.write(outFileName);

    return 0;
}


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