data/src/meshTools/indexedOctree/treeDataFace.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/>.

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

#include "treeDataFace.H"
#include "polyMesh.H"
#include "triangleFuncs.H"

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

namespace Foam
{
    defineTypeNameAndDebug(treeDataFace, 0);

    scalar treeDataFace::tolSqr = sqr(1e-6);
}


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

Foam::treeBoundBox Foam::treeDataFace::calcBb(const label facei) const
{
    const pointField& points = mesh_.points();

    const face& f = mesh_.faces()[facei];

    treeBoundBox bb(points[f[0]], points[f[0]]);

    for (label fp = 1; fp < f.size(); fp++)
    {
        const point& p = points[f[fp]];

        bb.min() = min(bb.min(), p);
        bb.max() = max(bb.max(), p);
    }
    return bb;
}


void Foam::treeDataFace::update()
{
    forAll(faceLabels_, i)
    {
        isTreeFace_.set(faceLabels_[i], 1);
    }

    if (cacheBb_)
    {
        bbs_.setSize(faceLabels_.size());

        forAll(faceLabels_, i)
        {
            bbs_[i] = calcBb(faceLabels_[i]);
        }
    }
}


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

Foam::treeDataFace::treeDataFace
(
    const bool cacheBb,
    const primitiveMesh& mesh,
    const labelUList& faceLabels
)
:
    mesh_(mesh),
    faceLabels_(faceLabels),
    isTreeFace_(mesh.nFaces(), 0),
    cacheBb_(cacheBb)
{
    update();
}


Foam::treeDataFace::treeDataFace
(
    const bool cacheBb,
    const primitiveMesh& mesh,
    labelList&& faceLabels
)
:
    mesh_(mesh),
    faceLabels_(faceLabels),
    isTreeFace_(mesh.nFaces(), 0),
    cacheBb_(cacheBb)
{
    update();
}


Foam::treeDataFace::treeDataFace
(
    const bool cacheBb,
    const primitiveMesh& mesh
)
:
    mesh_(mesh),
    faceLabels_(identityMap(mesh_.nFaces())),
    isTreeFace_(mesh.nFaces(), 0),
    cacheBb_(cacheBb)
{
    update();
}


Foam::treeDataFace::treeDataFace
(
    const bool cacheBb,
    const polyPatch& patch
)
:
    mesh_(patch.mesh()),
    faceLabels_(identityMap(patch.start(), patch.size())),
    isTreeFace_(mesh_.nFaces(), 0),
    cacheBb_(cacheBb)
{
    update();
}


Foam::treeDataFace::findNearestOp::findNearestOp
(
    const indexedOctree<treeDataFace>& tree
)
:
    tree_(tree)
{}


Foam::treeDataFace::findIntersectOp::findIntersectOp
(
    const indexedOctree<treeDataFace>& tree
)
:
    tree_(tree)
{}


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

Foam::pointField Foam::treeDataFace::shapePoints() const
{
    pointField cc(faceLabels_.size());

    forAll(faceLabels_, i)
    {
        cc[i] = mesh_.faceCentres()[faceLabels_[i]];
    }

    return cc;
}


Foam::volumeType Foam::treeDataFace::getVolumeType
(
    const indexedOctree<treeDataFace>& oc,
    const point& sample
) const
{
    // Need to determine whether sample is 'inside' or 'outside'
    // Done by finding nearest face. This gives back a face which is
    // guaranteed to contain nearest point. This point can be
    // - in interior of face: compare to face normal
    // - on edge of face: compare to edge normal
    // - on point of face: compare to point normal
    // Unfortunately the octree does not give us back the intersection point
    // or where on the face it has hit so we have to recreate all that
    // information.


    // Find nearest face to sample
    pointIndexHit info = oc.findNearest(sample, sqr(great));

    if (info.index() == -1)
    {
        FatalErrorInFunction
            << "Could not find " << sample << " in octree."
            << abort(FatalError);
    }


    // Get actual intersection point on face
    label facei = faceLabels_[info.index()];

    if (debug & 2)
    {
        Pout<< "getSampleType : sample:" << sample
            << " nearest face:" << facei;
    }

    const pointField& points = mesh_.points();

    // Retest to classify where on face info is. Note: could be improved. We
    // already have point.

    const face& f = mesh_.faces()[facei];
    const vector& area = mesh_.faceAreas()[facei];
    const point& fc = mesh_.faceCentres()[facei];

    pointHit curHit = f.nearestPoint(sample, points);
    const point& curPt = curHit.rawPoint();

    //
    // 1] Check whether sample is above face
    //

    if (curHit.hit())
    {
        // Nearest point inside face. Compare to face normal.

        if (debug & 2)
        {
            Pout<< " -> face hit:" << curPt
                << " comparing to face normal " << area << endl;
        }
        return indexedOctree<treeDataFace>::getSide(area, sample - curPt);
    }

    if (debug & 2)
    {
        Pout<< " -> face miss:" << curPt;
    }

    //
    // 2] Check whether intersection is on one of the face vertices or
    //    face centre
    //

    const scalar typDimSqr = mag(area) + vSmall;

    forAll(f, fp)
    {
        if ((magSqr(points[f[fp]] - curPt)/typDimSqr) < tolSqr)
        {
            // Face intersection point equals face vertex fp

            // Calculate point normal (wrong: uses face normals instead of
            // triangle normals)
            const labelList& pFaces = mesh_.pointFaces()[f[fp]];

            vector pointNormal(Zero);

            forAll(pFaces, i)
            {
                if (isTreeFace_.get(pFaces[i]) == 1)
                {
                    vector n = mesh_.faceAreas()[pFaces[i]];
                    n /= mag(n) + vSmall;

                    pointNormal += n;
                }
            }

            if (debug & 2)
            {
                    Pout<< " -> face point hit :" << points[f[fp]]
                        << " point normal:" << pointNormal
                        << " distance:"
                        << magSqr(points[f[fp]] - curPt)/typDimSqr << endl;
            }
            return indexedOctree<treeDataFace>::getSide
            (
                pointNormal,
                sample - curPt
            );
        }
    }
    if ((magSqr(fc - curPt)/typDimSqr) < tolSqr)
    {
        // Face intersection point equals face centre. Normal at face centre
        // is already average of face normals

        if (debug & 2)
        {
            Pout<< " -> centre hit:" << fc
                << " distance:" << magSqr(fc - curPt)/typDimSqr << endl;
        }

        return indexedOctree<treeDataFace>::getSide(area,  sample - curPt);
    }



    //
    // 3] Get the 'real' edge the face intersection is on
    //

    const labelList& myEdges = mesh_.faceEdges()[facei];

    forAll(myEdges, myEdgeI)
    {
        const edge& e = mesh_.edges()[myEdges[myEdgeI]];

        pointHit edgeHit =
            line<point, const point&>
            (
                points[e.start()],
                points[e.end()]
            ).nearestDist(sample);


        if ((magSqr(edgeHit.rawPoint() - curPt)/typDimSqr) < tolSqr)
        {
            // Face intersection point lies on edge e

            // Calculate edge normal (wrong: uses face normals instead of
            // triangle normals)
            const labelList& eFaces = mesh_.edgeFaces()[myEdges[myEdgeI]];

            vector edgeNormal(Zero);

            forAll(eFaces, i)
            {
                if (isTreeFace_.get(eFaces[i]) == 1)
                {
                    vector n = mesh_.faceAreas()[eFaces[i]];
                    n /= mag(n) + vSmall;

                    edgeNormal += n;
                }
            }

            if (debug & 2)
            {
                Pout<< " -> real edge hit point:" << edgeHit.rawPoint()
                    << " comparing to edge normal:" << edgeNormal
                    << endl;
            }

            // Found face intersection point on this edge. Compare to edge
            // normal
            return indexedOctree<treeDataFace>::getSide
            (
                edgeNormal,
                sample - curPt
            );
        }
    }


    //
    // 4] Get the internal edge the face intersection is on
    //

    forAll(f, fp)
    {
        pointHit edgeHit = line<point, const point&>
        (
            points[f[fp]],
            fc
        ).nearestDist(sample);

        if ((magSqr(edgeHit.rawPoint() - curPt)/typDimSqr) < tolSqr)
        {
            // Face intersection point lies on edge between two face triangles

            // Calculate edge normal as average of the two triangle normals
            vector e = points[f[fp]] - fc;
            vector ePrev = points[f[f.rcIndex(fp)]] - fc;
            vector eNext = points[f[f.fcIndex(fp)]] - fc;

            vector nLeft = ePrev ^ e;
            nLeft /= mag(nLeft) + vSmall;

            vector nRight = e ^ eNext;
            nRight /= mag(nRight) + vSmall;

            if (debug & 2)
            {
                Pout<< " -> internal edge hit point:" << edgeHit.rawPoint()
                    << " comparing to edge normal "
                    << 0.5*(nLeft + nRight)
                    << endl;
            }

            // Found face intersection point on this edge. Compare to edge
            // normal
            return indexedOctree<treeDataFace>::getSide
            (
                0.5*(nLeft + nRight),
                sample - curPt
            );
        }
    }

    if (debug & 2)
    {
        Pout<< "Did not find sample " << sample
            << " anywhere related to nearest face " << facei << endl
            << "Face:";

        forAll(f, fp)
        {
            Pout<< "    vertex:" << f[fp] << "  coord:" << points[f[fp]]
                << endl;
        }
    }

    // Can't determine status of sample with respect to nearest face.
    // Either
    // - tolerances are wrong. (if e.g. face has zero area)
    // - or (more likely) surface is not closed.

    return volumeType::unknown;
}


// Check if any point on shape is inside cubeBb.
bool Foam::treeDataFace::overlaps
(
    const label index,
    const treeBoundBox& cubeBb
) const
{
    // 1. Quick rejection: bb does not intersect face bb at all
    if (cacheBb_)
    {
        if (!cubeBb.overlaps(bbs_[index]))
        {
            return false;
        }
    }
    else
    {
        if (!cubeBb.overlaps(calcBb(faceLabels_[index])))
        {
            return false;
        }
    }

    const pointField& points = mesh_.points();


    // 2. Check if one or more face points inside
    label facei = faceLabels_[index];

    const face& f = mesh_.faces()[facei];
    if (cubeBb.containsAny(points, f))
    {
        return true;
    }

    // 3. Difficult case: all points are outside but connecting edges might
    // go through cube. Use triangle-bounding box intersection.
    const point& fc = mesh_.faceCentres()[facei];

    forAll(f, fp)
    {
        bool triIntersects = triangleFuncs::intersectBb
        (
            points[f[fp]],
            points[f[f.fcIndex(fp)]],
            fc,
            cubeBb
        );

        if (triIntersects)
        {
            return true;
        }
    }
    return false;
}


void Foam::treeDataFace::findNearestOp::operator()
(
    const labelUList& indices,
    const point& sample,

    scalar& nearestDistSqr,
    label& minIndex,
    point& nearestPoint
) const
{
    const treeDataFace& shape = tree_.shapes();

    forAll(indices, i)
    {
        const label index = indices[i];

        const face& f = shape.mesh().faces()[shape.faceLabels()[index]];

        pointHit nearHit = f.nearestPoint(sample, shape.mesh().points());
        scalar distSqr = sqr(nearHit.distance());

        if (distSqr < nearestDistSqr)
        {
            nearestDistSqr = distSqr;
            minIndex = index;
            nearestPoint = nearHit.rawPoint();
        }
    }
}


void Foam::treeDataFace::findNearestOp::operator()
(
    const labelUList& indices,
    const linePointRef& ln,

    treeBoundBox& tightest,
    label& minIndex,
    point& linePoint,
    point& nearestPoint
) const
{
    NotImplemented;
}


bool Foam::treeDataFace::findIntersectOp::operator()
(
    const label index,
    const point& start,
    const point& end,
    point& intersectionPoint
) const
{
    const treeDataFace& shape = tree_.shapes();

    // Do quick rejection test
    if (shape.cacheBb_)
    {
        const treeBoundBox& faceBb = shape.bbs_[index];

        if ((faceBb.posBits(start) & faceBb.posBits(end)) != 0)
        {
            // start and end in same block outside of faceBb.
            return false;
        }
    }

    const label facei = shape.faceLabels_[index];

    const vector dir(end - start);

    pointHit inter = shape.mesh_.faces()[facei].intersection
    (
        start,
        dir,
        shape.mesh_.faceCentres()[facei],
        shape.mesh_.points(),
        intersection::algorithm::halfRay
    );

    if (inter.hit() && inter.distance() <= 1)
    {
        // Note: no extra test on whether intersection is in front of us
        // since using half_ray
        intersectionPoint = inter.hitPoint();
        return true;
    }
    else
    {
        return false;
    }
}


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