/*
Copyright 2012-2022 Ronald Römer

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

#include <map>
#include <deque>
#include <vector>
#include <set>
#include <algorithm>
#include <cmath>
#include <functional>
#include <queue>
#include <memory>

#include <chrono>
#include <numeric>
#include <iterator>

#include <vtkInformation.h>
#include <vtkInformationVector.h>
#include <vtkDemandDrivenPipeline.h>
#include <vtkObjectFactory.h>
#include <vtkPolyDataAlgorithm.h>
#include <vtkCellData.h>
#include <vtkPointData.h>
#include <vtkMath.h>
#include <vtkIdList.h>
#include <vtkAppendPolyData.h>
#include <vtkKdTreePointLocator.h>
#include <vtkCleanPolyData.h>
#include <vtkPolyDataConnectivityFilter.h>
#include <vtkSmartPointer.h>
#include <vtkModifiedBSPTree.h>
#include <vtkCellArrayIterator.h>
#include <vtkKdTree.h>

#include "vtkPolyDataBooleanFilter.h"
#include "vtkPolyDataContactFilter.h"

#include "Utilities.h"

vtkStandardNewMacro(vtkPolyDataBooleanFilter);

vtkPolyDataBooleanFilter::vtkPolyDataBooleanFilter () {

    SetNumberOfInputPorts(2);
    SetNumberOfOutputPorts(3);

    timePdA = 0;
    timePdB = 0;

    contLines = vtkSmartPointer<vtkPolyData>::New();

    modPdA = vtkSmartPointer<vtkPolyData>::New();
    modPdB = vtkSmartPointer<vtkPolyData>::New();

    cellDataA = vtkSmartPointer<vtkCellData>::New();
    cellDataB = vtkSmartPointer<vtkCellData>::New();

    cellIdsA = vtkSmartPointer<vtkIdTypeArray>::New();
    cellIdsB = vtkSmartPointer<vtkIdTypeArray>::New();

    OperMode = OPER_UNION;

}

vtkPolyDataBooleanFilter::~vtkPolyDataBooleanFilter () {
    // nix mehr
}

int vtkPolyDataBooleanFilter::ProcessRequest(vtkInformation *request, vtkInformationVector **inputVector, vtkInformationVector *outputVector) {

    if (request->Has(vtkDemandDrivenPipeline::REQUEST_DATA())) {

        vtkInformation *inInfoA = inputVector[0]->GetInformationObject(0);
        vtkInformation *inInfoB = inputVector[1]->GetInformationObject(0);

        vtkPolyData *pdA = vtkPolyData::SafeDownCast(inInfoA->Get(vtkDataObject::DATA_OBJECT()));
        vtkPolyData *pdB = vtkPolyData::SafeDownCast(inInfoB->Get(vtkDataObject::DATA_OBJECT()));

        vtkInformation *outInfoA = outputVector->GetInformationObject(0);
        vtkInformation *outInfoB = outputVector->GetInformationObject(1);
        vtkInformation *outInfoC = outputVector->GetInformationObject(2);

        resultA = vtkPolyData::SafeDownCast(outInfoA->Get(vtkDataObject::DATA_OBJECT()));
        resultB = vtkPolyData::SafeDownCast(outInfoB->Get(vtkDataObject::DATA_OBJECT()));
        resultC = vtkPolyData::SafeDownCast(outInfoC->Get(vtkDataObject::DATA_OBJECT()));

        using clock = std::chrono::steady_clock;
        std::vector<clock::duration> times;
        clock::time_point start;

        if (pdA->GetMTime() > timePdA || pdB->GetMTime() > timePdB) {
            // eventuell vorhandene regionen vereinen

            vtkSmartPointer<vtkCleanPolyData> cleanA = vtkSmartPointer<vtkCleanPolyData>::New();
            cleanA->SetOutputPointsPrecision(DOUBLE_PRECISION);
            cleanA->SetTolerance(1e-6);
            cleanA->SetInputData(pdA);
            cleanA->Update();

            vtkSmartPointer<vtkCleanPolyData> cleanB = vtkSmartPointer<vtkCleanPolyData>::New();
            cleanB->SetOutputPointsPrecision(DOUBLE_PRECISION);
            cleanB->SetTolerance(1e-6);
            cleanB->SetInputData(pdB);
            cleanB->Update();

#ifdef DEBUG
            std::cout << "Exporting modPdA.vtk" << std::endl;
            WriteVTK("modPdA.vtk", cleanA->GetOutput());

            std::cout << "Exporting modPdB.vtk" << std::endl;
            WriteVTK("modPdB.vtk", cleanB->GetOutput());
#endif

            // CellData sichern

            cellDataA->DeepCopy(cleanA->GetOutput()->GetCellData());
            cellDataB->DeepCopy(cleanB->GetOutput()->GetCellData());

            // ermittelt kontaktstellen

            start = clock::now();

            vtkSmartPointer<vtkPolyDataContactFilter> cl = vtkSmartPointer<vtkPolyDataContactFilter>::New();
            cl->SetInputConnection(0, cleanA->GetOutputPort());
            cl->SetInputConnection(1, cleanB->GetOutputPort());
            cl->Update();

            times.push_back(clock::now()-start);

            contLines->DeepCopy(cl->GetOutput());

            modPdA->DeepCopy(cl->GetOutput(1));
            modPdB->DeepCopy(cl->GetOutput(2));

#ifdef DEBUG
            std::cout << "Exporting contLines.vtk" << std::endl;
            WriteVTK("contLines.vtk", contLines);

            std::cout << "Exporting modPdA_1.vtk" << std::endl;
            WriteVTK("modPdA_1.vtk", modPdA);

            std::cout << "Exporting modPdB_1.vtk" << std::endl;
            WriteVTK("modPdB_1.vtk", modPdB);
#endif

            if (contLines->GetNumberOfCells() == 0) {
                vtkErrorMacro("Inputs have no contact.");

                return 1;
            }

            // in den CellDatas steht drin, welche polygone einander schneiden

            contsA = vtkIdTypeArray::SafeDownCast(contLines->GetCellData()->GetScalars("cA"));
            contsB = vtkIdTypeArray::SafeDownCast(contLines->GetCellData()->GetScalars("cB"));

            vtkIdTypeArray *accuracy = vtkIdTypeArray::SafeDownCast(contLines->GetPointData()->GetScalars("accuracy"));

            vtkIdTypeArray *sourcesA = vtkIdTypeArray::SafeDownCast(contLines->GetCellData()->GetScalars("sourcesA"));
            vtkIdTypeArray *sourcesB = vtkIdTypeArray::SafeDownCast(contLines->GetCellData()->GetScalars("sourcesB"));

            vtkIdType i, numPts = contLines->GetNumberOfPoints();

            vtkSmartPointer<vtkIdList> cells = vtkSmartPointer<vtkIdList>::New();

            for (i = 0; i < numPts; i++) {
                contLines->GetPointCells(i, cells);

                if (cells->GetNumberOfIds() == 1) {
                    vtkErrorMacro("Contact ends suddenly.");
                    return 1;
                }

                if (accuracy->GetValue(i) == 1) {
                    vtkErrorMacro("Contact goes through a cell with a bad shape.");
                    return 1;
                }
            }

            // sichert die OrigCellIds

            vtkIdTypeArray *origCellIdsA = vtkIdTypeArray::SafeDownCast(modPdA->GetCellData()->GetScalars("OrigCellIds"));
            vtkIdTypeArray *origCellIdsB = vtkIdTypeArray::SafeDownCast(modPdB->GetCellData()->GetScalars("OrigCellIds"));

            cellIdsA->DeepCopy(origCellIdsA);
            cellIdsB->DeepCopy(origCellIdsB);

            vtkIdType numCellsA = modPdA->GetNumberOfCells(),
                numCellsB = modPdB->GetNumberOfCells();

            for (i = 0; i < numCellsA; i++) {
                origCellIdsA->SetValue(i, i);
            }

            for (i = 0; i < numCellsB; i++) {
                origCellIdsB->SetValue(i, i);
            }

            start = clock::now();

            if (GetPolyStrips(modPdA, contsA, sourcesA, polyStripsA) ||
                GetPolyStrips(modPdB, contsB, sourcesB, polyStripsB)) {

                vtkErrorMacro("Strips are invalid.");

                return 1;

            }

            times.push_back(clock::now()-start);

            // trennt die polygone an den linien

            start = clock::now();

            if (CutCells(modPdA, polyStripsA) ||
                CutCells(modPdB, polyStripsB)) {

                vtkErrorMacro("CutCells failed.");

                return 1;
            }

            times.push_back(clock::now()-start);

#ifdef DEBUG
            std::cout << "Exporting modPdA_2.vtk" << std::endl;
            WriteVTK("modPdA_2.vtk", modPdA);

            std::cout << "Exporting modPdB_2.vtk" << std::endl;
            WriteVTK("modPdB_2.vtk", modPdB);
#endif

            start = clock::now();

            RestoreOrigPoints(modPdA, polyStripsA);
            RestoreOrigPoints(modPdB, polyStripsB);

            times.push_back(clock::now()-start);

#ifdef DEBUG
            std::cout << "Exporting modPdA_3.vtk" << std::endl;
            WriteVTK("modPdA_3.vtk", modPdA);

            std::cout << "Exporting modPdB_3.vtk" << std::endl;
            WriteVTK("modPdB_3.vtk", modPdB);
#endif

            start = clock::now();

            ResolveOverlaps(modPdA, contsA, polyStripsA);
            ResolveOverlaps(modPdB, contsB, polyStripsB);

            times.push_back(clock::now()-start);

#ifdef DEBUG
            std::cout << "Exporting modPdA_4.vtk" << std::endl;
            WriteVTK("modPdA_4.vtk", modPdA);

            std::cout << "Exporting modPdB_4.vtk" << std::endl;
            WriteVTK("modPdB_4.vtk", modPdB);
#endif

            start = clock::now();

            AddAdjacentPoints(modPdA, contsA, polyStripsA);
            AddAdjacentPoints(modPdB, contsB, polyStripsB);

            times.push_back(clock::now()-start);

#ifdef DEBUG
            std::cout << "Exporting modPdA_5.vtk" << std::endl;
            WriteVTK("modPdA_5.vtk", modPdA);

            std::cout << "Exporting modPdB_5.vtk" << std::endl;
            WriteVTK("modPdB_5.vtk", modPdB);
#endif

            start = clock::now();

            DisjoinPolys(modPdA, polyStripsA);
            DisjoinPolys(modPdB, polyStripsB);

            times.push_back(clock::now()-start);

#ifdef DEBUG
            std::cout << "Exporting modPdA_6.vtk" << std::endl;
            WriteVTK("modPdA_6.vtk", modPdA);

            std::cout << "Exporting modPdB_6.vtk" << std::endl;
            WriteVTK("modPdB_6.vtk", modPdB);
#endif

            start = clock::now();

            MergePoints(modPdA, polyStripsA);
            MergePoints(modPdB, polyStripsB);

            times.push_back(clock::now()-start);

#ifdef DEBUG
            std::cout << "Exporting modPdA_7.vtk" << std::endl;
            WriteVTK("modPdA_7.vtk", modPdA);

            std::cout << "Exporting modPdB_7.vtk" << std::endl;
            WriteVTK("modPdB_7.vtk", modPdB);
#endif

            timePdA = pdA->GetMTime();
            timePdB = pdB->GetMTime();

        }

        start = clock::now();

        if (CombineRegions()) {
            vtkErrorMacro("Boolean operation failed.");

            return 1;
        }

        times.push_back(clock::now()-start);

// #ifdef DEBUG
        double sum = std::chrono::duration_cast<std::chrono::duration<double>>(std::accumulate(times.begin(), times.end(), clock::duration())).count();

        std::vector<clock::duration>::const_iterator itr;
        for (itr = times.begin(); itr != times.end(); itr++) {
            double time = std::chrono::duration_cast<std::chrono::duration<double>>(*itr).count();

            std::cout << "Time " << (itr-times.begin())
                << ": " << time << "s (" << (time/sum*100) << "%)"
                << std::endl;
        }
// #endif

    }

    return 1;

}

void vtkPolyDataBooleanFilter::GetStripPoints (vtkPolyData *pd, vtkIdTypeArray *sources, PStrips &pStrips, IdsType &lines) {

#ifdef DEBUG
    std::cout << "GetStripPoints()" << std::endl;
#endif

    StripPtsType &pts = pStrips.pts;
    const IdsType &poly = pStrips.poly;

    double a[3], b[3], sA[3], sB[3], u[3], v[3], w[3], n, t, d;

    std::map<vtkIdType, vtkIdType> allPts;

    vtkSmartPointer<vtkIdList> line = vtkSmartPointer<vtkIdList>::New();

    for (auto lineId : lines) {
        contLines->GetCellPoints(lineId, line);

        // std::cout << "? " << contsA->GetValue(lineId)
        //     << ", " << contsB->GetValue(lineId)
        //     << ", [" << line->GetId(0)
        //     << ", " << line->GetId(1)
        //     << "]"
        //     << std::endl;

        allPts.emplace(line->GetId(0), sources->GetTypedComponent(lineId, 0));
        allPts.emplace(line->GetId(1), sources->GetTypedComponent(lineId, 1));
    }

    decltype(allPts)::const_iterator itr;

    for (itr = allPts.begin(); itr != allPts.end(); ++itr) {
        StripPt sp;
        sp.ind = itr->first;

        // die koordinaten
        double pt[3];
        contLines->GetPoint(sp.ind, pt);

        Cpy(sp.pt, pt, 3);

        IdsType::const_iterator itrA, itrB;

        for (itrA = poly.begin(); itrA != poly.end(); ++itrA) {
            itrB = itrA+1;

            if (itrB == poly.end()) {
                itrB = poly.begin();
            }

            if (itr->second != NOTSET && *itrA != itr->second) {
                continue;
            }

            pd->GetPoint(*itrA, a);
            pd->GetPoint(*itrB, b);

            vtkMath::Subtract(a, pt, sA);
            vtkMath::Subtract(b, pt, sB);

            // richtungsvektor und länge der kante

            vtkMath::Subtract(b, a, u);
            n = vtkMath::Norm(u);

            // d und t zur kante

            vtkMath::Subtract(pt, a, v);
            t = vtkMath::Dot(v, u)/(n*n);

            vtkMath::Cross(v, u, w);
            d = vtkMath::Norm(w)/n;

            if (d < 1e-5 && t > -1e-5 && t < 1+1e-5) {
                sp.edge[0] = *itrA;
                sp.edge[1] = *itrB;

                sp.t = std::min(1., std::max(0., t));

                if (vtkMath::Norm(sA) < 1e-5) {
                    Cpy(sp.captPt, a, 3);
                    sp.capt = Capt::A;

                } else if (vtkMath::Norm(sB) < 1e-5) {
                    Cpy(sp.captPt, b, 3);
                    sp.capt = Capt::B;

                } else {
                    // u ist nicht normiert
                    vtkMath::MultiplyScalar(u, t);

                    double x[3];
                    vtkMath::Add(a, u, x);

                    // projektion
                    Cpy(sp.captPt, x, 3);

                    sp.capt = Capt::EDGE;

                }
            }

            // std::cout << "? "
            //     << sp.ind
            //     << ", " << d
            //     << ", " << t
            //     << ", " << sp.capt
            //     << std::endl;
        }

        if (itr->second != NOTSET && sp.edge[0] == NOTSET) {
            sp.catched = false;
        }

        pts.emplace(sp.ind, std::move(sp));

    }

    StripPtsType::iterator itr2;

    for (itr2 = pts.begin(); itr2 != pts.end(); ++itr2) {
        StripPt &sp = itr2->second;

        if (sp.capt != Capt::NOT) {
            if (sp.capt == Capt::B) {
                sp.t = 0;

                sp.edge[0] = sp.edge[1];

                auto itrA = std::find(poly.begin(), poly.end(), sp.edge[0]),
                    itrB = itrA+1;

                if (itrB == poly.end()) {
                    itrB = poly.begin();
                }

                sp.edge[1] = *itrB;

                sp.capt = Capt::A;

            }

            // für den schnitt werden die eingerasteten koordinaten verwendet

            Cpy(sp.cutPt, sp.captPt, 3);
        } else {

            Cpy(sp.cutPt, sp.pt, 3);
        }

        sp.history.emplace_back(sp.edge[0], sp.edge[1]);

    }

#ifdef DEBUG
    std::cout << "pts: " << std::endl;
    for (itr2 = pts.begin(); itr2 != pts.end(); ++itr2) {
        std::cout << itr2->first << ": " << itr2->second << std::endl;
    }
#endif

}

bool vtkPolyDataBooleanFilter::GetPolyStrips (vtkPolyData *pd, vtkIdTypeArray *conts, vtkIdTypeArray *sources, PolyStripsType &polyStrips) {
#ifdef DEBUG
    std::cout << "GetPolyStrips()" << std::endl;
#endif

    polyStrips.clear();

    std::map<vtkIdType, IdsType> polyLines;

    for (vtkIdType i = 0; i < conts->GetNumberOfTuples(); i++) {
        vtkIdType poly = conts->GetValue(i);

        /*if (poly != 1641) {
            continue;
        }*/

        polyLines[poly].push_back(i);
    }

    std::vector<std::reference_wrapper<StripPt>> notCatched;

    std::map<vtkIdType, IdsType>::iterator itr;

    for (itr = polyLines.begin(); itr != polyLines.end(); ++itr) {

        IdsType &lines = itr->second;
        RemoveDuplicates(lines);

        polyStrips.emplace(std::piecewise_construct,
            std::forward_as_tuple(itr->first),
            std::forward_as_tuple(pd, itr->first));

        PStrips &pStrips = polyStrips.at(itr->first);

        GetStripPoints(pd, sources, pStrips, lines);

        for (auto &sp : pStrips.pts) {
            sp.second.polyId = itr->first;

            if (!sp.second.catched) {
                notCatched.push_back(sp.second);
            }
        }

    }

    auto Next = [](const IdsType &ids, vtkIdType id) -> vtkIdType {
        IdsType::const_iterator itr;

        itr = std::find(ids.begin(), ids.end(), id);

        if (++itr == ids.end()) {
            itr = ids.begin();
        }

        return *itr;
    };

    for (StripPt &sp : notCatched) {
        for (itr = polyLines.begin(); itr != polyLines.end(); ++itr) {
            const PStrips &pStrips = polyStrips.at(itr->first);

            try {
                const StripPt &corr = pStrips.pts.at(sp.ind);

                if (&corr != &sp) {
                    if (corr.capt == Capt::A) {
                        sp.capt = Capt::A;
                        sp.edge[0] = corr.edge[0];
                        sp.edge[1] = Next(polyStrips.at(sp.polyId).poly, sp.edge[0]);

                        sp.t = 0;

                        Cpy(sp.captPt, corr.captPt, 3);
                        Cpy(sp.cutPt, sp.captPt, 3);

                        sp.history.emplace_back(sp.edge[0], sp.edge[1]);

                        sp.catched = true;

                    }
                }
            } catch (...) {}

        }

        if (!sp.catched) {
            std::cout << sp << std::endl;
        }

        assert(sp.catched);

    }

    vtkSmartPointer<vtkIdList> cells = vtkSmartPointer<vtkIdList>::New(),
        line = vtkSmartPointer<vtkIdList>::New();

    vtkIdType i, numCells;

    StripPtsType::const_iterator itr2;

    for (itr = polyLines.begin(); itr != polyLines.end(); ++itr) {
        PStrips &pStrips = polyStrips.at(itr->first);

        const IdsType &lines = itr->second;
        const StripPtsType &pts = pStrips.pts;

        for (itr2 = pts.begin(); itr2 != pts.end(); ++itr2) {
            // ist der punkt auf einer kante, dürfen von ihm mehr als 2 linien ausgehen

            const StripPt &pt = itr2->second;

            if (pt.capt == Capt::NOT) {
                contLines->GetPointCells(pt.ind, cells);

                numCells = cells->GetNumberOfIds();

                std::set<vtkIdType> ends;

                for (i = 0; i < numCells; i++) {
                    contLines->GetCellPoints(cells->GetId(i), line);

                    ends.insert(pt.ind == line->GetId(0) ? line->GetId(1) : line->GetId(0));
                }

                if (ends.size() > 2) {
                    return true;
                }
            }
        }

        // zusammensetzen

        std::deque<Pair> _lines;

        vtkIdList *linePts = vtkIdList::New();

        for (auto &i : lines) {
            contLines->GetCellPoints(i, linePts);
            _lines.emplace_back(linePts->GetId(0), linePts->GetId(1));
        }

        linePts->Delete();

        decltype(_lines)::iterator _itr;

        auto FindRight = [&pts, &_lines, &_itr](StripType &strip, const std::size_t &id) -> bool {
            auto &right = strip.back();

            if (pts.at(right.ind).capt == Capt::NOT) {
                for (_itr = _lines.begin(); _itr != _lines.end(); ++_itr) {
                    if (_itr->f == right.ind) {
                        strip.emplace_back(_itr->g, id);

                        _lines.erase(_itr);
                        return true;
                    } else if (_itr->g == right.ind) {
                        strip.emplace_back(_itr->f, id);

                        _lines.erase(_itr);
                        return true;
                    }
                }
            }

            return false;
        };

        auto FindLeft = [&pts, &_lines, &_itr](StripType &strip, const std::size_t &id) -> bool {
            auto &left = strip.front();

            if (pts.at(left.ind).capt == Capt::NOT) {
                for (_itr = _lines.begin(); _itr != _lines.end(); ++_itr) {
                    if (_itr->f == left.ind) {
                        strip.emplace_front(_itr->g, id);

                        _lines.erase(_itr);
                        return true;
                    } else if (_itr->g == left.ind) {
                        strip.emplace_front(_itr->f, id);

                        _lines.erase(_itr);
                        return true;
                    }
                }
            }

            return false;
        };

        std::size_t stripId {0};

        while (!_lines.empty()) {
            auto &last = _lines.back();

            StripType strip {{last.f, stripId}, {last.g, stripId}};
            _lines.pop_back();

            while (FindRight(strip, stripId)) {}
            while (FindLeft(strip, stripId)) {}

            pStrips.strips.push_back(std::move(strip));

            stripId++;

        }

        CompleteStrips(pStrips);

    }

    // sucht nach schnitten zw. den strips

    {

        PolyStripsType::const_iterator itr;
        StripType::const_iterator itr2;

        for (itr = polyStrips.begin(); itr != polyStrips.end(); ++itr) {
            const PStrips &pStrips = itr->second;

            const StripsType &strips = pStrips.strips;
            const StripPtsType &pts = pStrips.pts;
            const Base &base = pStrips.base;

            vtkSmartPointer<vtkPoints> treePts = vtkSmartPointer<vtkPoints>::New();

            vtkSmartPointer<vtkPolyData> treePd = vtkSmartPointer<vtkPolyData>::New();
            treePd->Allocate(1);

            std::map<vtkIdType, vtkIdType> ptIds;
            
            double pt[2];

            for (const auto &p : pts) {
                Transform(p.second.pt, pt, base);

                ptIds.emplace(p.first, treePts->InsertNextPoint(pt[0], pt[1], 0));
            }

            for (const StripType &strip : strips) {
                for (itr2 = strip.begin(); itr2 != strip.end()-1; ++itr2) {

                    vtkIdList *line = vtkIdList::New();
                    line->InsertNextId(ptIds[itr2->ind]);
                    line->InsertNextId(ptIds[(itr2+1)->ind]);

                    treePd->InsertNextCell(VTK_LINE, line);

                    line->Delete();
                }
            }

            treePd->SetPoints(treePts);

            vtkSmartPointer<vtkModifiedBSPTree> tree = vtkSmartPointer<vtkModifiedBSPTree>::New();
            tree->SetDataSet(treePd);
            tree->BuildLocator();

            vtkIdType numA, numB;
            const vtkIdType *lineA, *lineB;

            auto lineItr = vtk::TakeSmartPointer(treePd->GetLines()->NewIterator());

            for (lineItr->GoToFirstCell(); !lineItr->IsDoneWithTraversal(); lineItr->GoToNextCell()) {
                lineItr->GetCurrentCell(numA, lineA);

                double ptA[3], ptB[3];

                treePts->GetPoint(lineA[0], ptA);
                treePts->GetPoint(lineA[1], ptB);

                vtkSmartPointer<vtkIdList> lineIds = vtkSmartPointer<vtkIdList>::New();

                tree->IntersectWithLine(ptA, ptB, 1e-5, nullptr, lineIds);

                for (vtkIdType i = 0; i < lineIds->GetNumberOfIds(); i++) {
                    treePd->GetCellPoints(lineIds->GetId(i), numB, lineB);

                    if (lineB[0] != lineA[0] && lineB[1] != lineA[0] && lineB[0] != lineA[1] && lineB[1] != lineA[1]) {
                        // schnitt gefunden

                        return true;
                    }
                }
            }

        }

    }

    return false;

}

void vtkPolyDataBooleanFilter::RemoveDuplicates (IdsType &lines) {

    IdsType unique;

    // die indexe der enden auf übereinstimmung prüfen

    vtkIdList *linePtsA = vtkIdList::New();
    vtkIdList *linePtsB = vtkIdList::New();

    std::size_t i, j, numLines = lines.size();

    for (i = 0; i < numLines-1; i++) {
        j = i+1;

        contLines->GetCellPoints(lines[i], linePtsA);

        while (j < lines.size()) {
            contLines->GetCellPoints(lines[j], linePtsB);

            if ((linePtsA->GetId(0) == linePtsB->GetId(0) && linePtsA->GetId(1) == linePtsB->GetId(1)) ||
                (linePtsA->GetId(0) == linePtsB->GetId(1) && linePtsA->GetId(1) == linePtsB->GetId(0))) {
                // stimmen überein
                break;
            }

            j++;
        }

        if (j == numLines) {
            // keine vorzeitige unterbrechung der while-schleife
            unique.push_back(lines[i]);
        }
    }

    unique.push_back(lines.back());

    linePtsA->Delete();
    linePtsB->Delete();

    lines.swap(unique);

}

void vtkPolyDataBooleanFilter::CompleteStrips (PStrips &pStrips) {
    StripsType::iterator itr;

    for (itr = pStrips.strips.begin(); itr != pStrips.strips.end(); ++itr) {
        const StripPt &start = pStrips.pts[itr->front().ind],
            &end = pStrips.pts[itr->back().ind];

        if (start.ind != end.ind) {
            if (start.capt == Capt::NOT) {
                StripType s(itr->rbegin(), itr->rend()-1);
                itr->insert(itr->begin(), s.begin(), s.end());

            } else if (end.capt == Capt::NOT) {
                StripType s(itr->rbegin()+1, itr->rend());
                itr->insert(itr->end(), s.begin(), s.end());

            }
        }
    }
}

bool vtkPolyDataBooleanFilter::HasArea (const StripType &strip) const {
    bool area = true;

    std::size_t i, n = strip.size();

    if (n%2 == 1) {
        for (i = 0; i < (n-1)/2; i++) {
            area = strip[i].ind != strip[n-i-1].ind;
        }
    }

    return area;
}

void ComputeNormal (const StripPtsType &pts, const RefsType &poly, double *n) {
    n[0] = 0; n[1] = 0; n[2] = 0;

    RefsType::const_iterator itrA, itrB;

    for (itrA = poly.begin(); itrA != poly.end(); ++itrA) {
        itrB = itrA+1;

        if (itrB == poly.end()) {
            itrB = poly.begin();
        }

        const StripPtR &spA = *itrA,
            &spB = *itrB;

        auto pA = pts.find(spA.ind);
        auto pB = pts.find(spB.ind);

        const double *ptA = pA->second.cutPt,
            *ptB = pB->second.cutPt;

        n[0] += (ptA[1]-ptB[1])*(ptA[2]+ptB[2]);
        n[1] += (ptA[2]-ptB[2])*(ptA[0]+ptB[0]);
        n[2] += (ptA[0]-ptB[0])*(ptA[1]+ptB[1]);
    }

    vtkMath::Normalize(n);
}

bool vtkPolyDataBooleanFilter::CutCells (vtkPolyData *pd, PolyStripsType &polyStrips) {
#ifdef DEBUG
    std::cout << "CutCells()" << std::endl;
#endif

    vtkPoints *pdPts = pd->GetPoints();

    vtkIdTypeArray *origCellIds = vtkIdTypeArray::SafeDownCast(pd->GetCellData()->GetScalars("OrigCellIds"));

    PolyStripsType::iterator itr;

    for (itr = polyStrips.begin(); itr != polyStrips.end(); ++itr) {

        vtkIdType polyInd = itr->first;
        PStrips &pStrips = itr->second;

        /*if (polyInd != 1641) {
            continue;
        }*/

        StripsType &strips = pStrips.strips;
        StripPtsType &pts = pStrips.pts;

        IdsType &poly = pStrips.poly;

        vtkIdType origId = origCellIds->GetValue(polyInd);

#ifdef DEBUG
        std::cout << "polyInd " << polyInd << ", poly [";
        for (auto &p : poly) {
            std::cout << p << ", ";
        }
        std::cout << "]" << std::endl;
#endif

        std::size_t numPts = poly.size();

        std::map<vtkIdType, RefsType> edges;

        StripsType::iterator itr2;
        StripType::iterator itr3;

        // holes sichern
        StripsType holes;

        auto fct = [&](const StripType &s) {
            return pts[s.front().ind].capt == Capt::NOT && pts[s.back().ind].capt == Capt::NOT;
        };

        std::copy_if(strips.begin(), strips.end(), std::back_inserter(holes), fct);

        strips.erase(std::remove_if(strips.begin(), strips.end(), fct), strips.end());

        for (itr2 = strips.begin(); itr2 != strips.end(); ++itr2) {
            StripType &strip = *itr2;

#ifdef DEBUG
            std::cout << (itr2-strips.begin()) << ". strip [";
            for (auto &s : strip) {
                std::cout << s.ind << ", ";
            }
            std::cout << "]" << std::endl;
#endif

            // init
            if (pts[strip.front().ind].edge[0] == pts[strip.back().ind].edge[0]
                && strip.front().ind != strip.back().ind
                && pts[strip.front().ind].t > pts[strip.back().ind].t) {

                std::reverse(strip.begin(), strip.end());
            }

            StripPt &start = pts[strip.front().ind],
                &end = pts[strip.back().ind];

            strip.front().side = Side::START;
            strip.back().side = Side::END;

            strip.front().ref = start.edge[0];
            strip.back().ref = end.edge[0];

            // nachfolgend könnte man dann anfang und ende weglassen

            for (itr3 = strip.begin(); itr3 != strip.end(); ++itr3) {
                StripPt &sp = pts[itr3->ind];

                itr3->desc[0] = pdPts->InsertNextPoint(sp.cutPt);
                itr3->desc[1] = pdPts->InsertNextPoint(sp.cutPt);

#ifdef DEBUG
                std::cout << sp << " => " << *itr3 << std::endl;
#endif

            }

            // ordnet zu

            edges[start.edge[0]].push_back(std::ref(strip.front()));
            edges[end.edge[0]].push_back(std::ref(strip.back()));
        }

        // sortiert die punkte auf den kanten

        std::map<vtkIdType, RefsType>::iterator itr4;

        IdsType::iterator itr5;
        StripType::reverse_iterator itr6;

        RefsType::iterator itr7;

        for (itr4 = edges.begin(); itr4 != edges.end(); ++itr4) {
            RefsType &edge = itr4->second;

#ifdef DEBUG
            std::cout << "edge (" << itr4->first << ", _)" << std::endl;
#endif

            std::sort(edge.begin(), edge.end(), [&](const StripPtR &a, const StripPtR &b) {
                const StripPt &a_ = pts[a.ind],
                    &b_ = pts[b.ind];

#ifdef DEBUG
                // std::cout << "a_: " << a_ << " -> strip " << a.strip << std::endl;
                // std::cout << "b_: " << b_ << " -> strip " << b.strip << std::endl;
#endif

                if (a_.ind == b_.ind) {
                    // strips beginnen im gleichen punkt

                    if (a.strip != b.strip) {
                        // gehören nicht dem gleichen strip an

                        StripType &stripA = strips[a.strip],
                            &stripB = strips[b.strip];

                        // andere enden ermitteln

                        const StripPtR &eA = (&a == &(stripA.front())) ? stripA.back() : stripA.front(),
                            &eB = (&b == &(stripB.front())) ? stripB.back() : stripB.front();

                        const StripPt &eA_ = pts[eA.ind],
                            &eB_ = pts[eB.ind];

#ifdef DEBUG
                        // std::cout << "eA_: " << eA_ << std::endl;
                        // std::cout << "eB_: " << eA_ << std::endl;
#endif

                        if (eA_.ind != eB_.ind) {
                            auto i = std::find(poly.begin(), poly.end(), itr4->first)-poly.begin(),
                                iA = std::find(poly.begin(), poly.end(), eA_.edge[0])-poly.begin(),
                                iB = std::find(poly.begin(), poly.end(), eB_.edge[0])-poly.begin();

                            double dA = static_cast<double>(Mod(iA-i, numPts))+eA_.t,
                                dB = static_cast<double>(Mod(iB-i, numPts))+eB_.t;

                            if (i == iA && a_.t > eA_.t) {
                               dA += static_cast<double>(numPts);
                            }

                            if (i == iB && b_.t > eB_.t) {
                               dB += static_cast<double>(numPts);
                            }

#ifdef DEBUG
                            // std::cout << "dA=" << dA << ", dB=" << dB << std::endl;
#endif

                            return dB < dA;
                        } else {
                            RefsType poly_;

                            if (a.side == Side::START) {
                                poly_.insert(poly_.end(), stripA.begin(), stripA.end());
                            } else {
                                poly_.insert(poly_.end(), stripA.rbegin(), stripA.rend());
                            }

                            if (b.side == Side::START) {
                                poly_.insert(poly_.end(), stripB.rbegin()+1, stripB.rend()-1);
                            } else {
                                poly_.insert(poly_.end(), stripB.begin()+1, stripB.end()-1);
                            }

                            double n[3];
                            ComputeNormal(pts, poly_, n);

                            double ang = vtkMath::Dot(pStrips.n, n);

#ifdef DEBUG
                            // std::cout << "ang=" << ang*180/PI << std::endl;
#endif

                            return ang < .999999;

                        }
                    } else {
                        // gleicher strip

                        StripType &strip = strips[a.strip];

                        if (HasArea(strip)) {
                            RefsType poly_(strip.begin(), strip.end()-1);

                            double n[3];
                            ComputeNormal(pts, poly_, n);

                            double ang = vtkMath::Dot(pStrips.n, n);

                            if (ang > .999999) {
                                std::reverse(strip.begin(), strip.end());
                                return true;
                            } else {
                                return false;
                            }

                        } else {
                            // reihenfolge von a und b bereits richtig
                            return false;
                        }
                    }

                } else {
                    return a_.t < b_.t;
                }
            });

#ifdef DEBUG
            for (auto& p : edge) {
                std::cout << p << std::endl;
            }
#endif

        }

        // baut die strips ein

        std::deque<IdsType> polys;
        polys.push_back(pStrips.poly);

        for (itr2 = strips.begin(); itr2 != strips.end(); ++itr2) {
            StripType &strip = *itr2;

            StripPtR &start = strip.front(),
                &end = strip.back();

#ifdef DEBUG
            std::cout << "strip " << start.strip
                << " , refs (" << start.ref << ", " << end.ref << ")"
                << std::endl;
#endif

            std::size_t cycle = 0;

            while (true) {
                if (cycle == polys.size()) {
                    break;
                }

                IdsType next = polys.front();
                polys.pop_front();

                std::vector<IdsType> newPolys(2);

                if (std::find(next.begin(), next.end(), start.ref) != next.end()) {
                    if (start.ref == end.ref) {
                        for (itr5 = next.begin(); itr5 != next.end(); ++itr5) {
                            newPolys[0].push_back(*itr5);

#ifdef DEBUG
                            std::cout << "adding " << *itr5 << " to 0" << std::endl;
#endif

                            if (*itr5 == start.ref) {
                                for (itr3 = strip.begin(); itr3 != strip.end(); ++itr3) {
                                    newPolys[0].push_back(itr3->desc[0]);

#ifdef DEBUG
                                    std::cout << "adding " << itr3->desc[0] << " to 0" << std::endl;
#endif

                                }
                            }
                        }

                        // strip selbst ist ein polygon

                        for (itr6 = strip.rbegin(); itr6 != strip.rend(); ++itr6) {
                            newPolys[1].push_back(itr6->desc[1]);

#ifdef DEBUG
                            std::cout << "adding " << itr6->desc[1] << " to 1" << std::endl;
#endif

                        }

                    } else {
                        std::size_t curr = 0;

                        for (itr5 = next.begin(); itr5 != next.end(); ++itr5) {
                            IdsType &poly = newPolys[curr];

                            poly.push_back(*itr5);

#ifdef DEBUG
                            std::cout << "adding " << *itr5 << " to " << curr << std::endl;
#endif

                            if (*itr5 == start.ref) {
                                for (itr3 = strip.begin(); itr3 != strip.end(); ++itr3) {
                                    poly.push_back(itr3->desc[0]);

#ifdef DEBUG
                                    std::cout << "adding " << itr3->desc[0] << " to " << curr << std::endl;
#endif

                                }

                                curr = curr == 0 ? 1 : 0;

                            } else if (*itr5 == end.ref) {
                                for (itr6 = strip.rbegin(); itr6 != strip.rend(); ++itr6) {
                                    poly.push_back(itr6->desc[1]);

#ifdef DEBUG
                                    std::cout << "adding " << itr6->desc[1] << " to " << curr << std::endl;
#endif

                                }

                                curr = curr == 0 ? 1 : 0;
                            }

                        }
                    }
                }

                if (!newPolys[1].empty()) {
                    // refs aktualisieren

                    for (itr4 = edges.begin(); itr4 != edges.end(); ++itr4) {
                        RefsType &edge = itr4->second;

                        RefsType::iterator itrA;

                        for (itrA = edge.begin()+1; itrA != edge.end(); ++itrA) {
                            StripPtR &sp = *itrA;

                            if (sp.strip > start.strip) {
#ifdef DEBUG
                                std::cout << "sp: ind " << sp.ind << ", strip " << sp.strip << std::endl;
#endif

                                RefsType::const_reverse_iterator itrB(itrA);

                                std::shared_ptr<StripPtR> _p;

                                for (; itrB != edge.rend(); ++itrB) {
                                    const StripPtR &p = *itrB;

                                    if (p.strip != sp.strip) {
                                        if (p.strip <= start.strip) {
#ifdef DEBUG
                                            std::cout << "ref " << sp.ref;
#endif

                                            if (p.side == Side::END) {
                                                sp.ref = p.desc[0];
                                            } else {
                                                sp.ref = p.desc[1];
                                            }

#ifdef DEBUG
                                            std::cout << " -> " << sp.ref << " (from strip " << p.strip << ", ind " << p.ind << ")" << std::endl;
#endif

                                            _p = std::make_shared<StripPtR>(p);

                                            break;

                                        }
                                    } else {
#ifdef DEBUG
                                        std::cout << "~1 ref " << sp.ref << " -> " << p.ref << " (from strip " << p.strip << ", ind " << p.ind << ")" << std::endl;
#endif

                                        sp.ref = p.ref;
                                        break;
                                    }
                                }

                                RefsType::const_iterator itrC(itrA);

                                ++itrC;

                                for (; itrC != edge.end(); ++itrC) {
                                    const StripPtR &p = *itrC;

                                    if (p.ind != sp.ind) {
                                        break;
                                    }

                                    if (p.strip <= start.strip) {
                                        if (_p && p.ind == _p->ind && p.strip < _p->strip) {
                                            break;
                                        }

#ifdef DEBUG
                                        std::cout << "~2 ref " << sp.ref;
#endif

                                        if (p.side == Side::START) {
                                            sp.ref = p.desc[0];
                                        } else {
                                            sp.ref = p.desc[1];
                                        }

#ifdef DEBUG
                                        std::cout << " -> " << sp.ref << " (from strip " << p.strip << ", ind " << p.ind << ")" << std::endl;
#endif

                                        break;
                                    }

                                }
                            }
                        }

                        // erstellt die history

                        auto _s = std::find_if(edge.begin(), edge.end(), [&start](const StripPtR &r) {
                            return &start == &r;
                        });

                        if (_s != edge.end()) {
                            for (itr7 = edge.begin(); itr7 != edge.end(); ++itr7) {
                                StripPtR &sp = *itr7;
                                StripPt &_sp = pts[sp.ind];
                                auto &history = _sp.history;

                                if (&sp != &start) {
                                    if (_sp.t < pts[start.ind].t) {
                                        history.push_back({history.back().f, start.desc[0]});
                                    } else {
                                        history.push_back({start.desc[1], history.back().g});
                                    }

                                }

                            }
                        }

                        auto _e = std::find_if(edge.begin(), edge.end(), [&end](const StripPtR &r) {
                            return &end == &r;
                        });

                        if (_e != edge.end()) {
                            for (itr7 = edge.begin(); itr7 != edge.end(); ++itr7) {
                                StripPtR &sp = *itr7;
                                StripPt &_sp = pts[sp.ind];
                                auto &history = _sp.history;

                                if (&sp != &end) {
                                    if (_sp.t < pts[end.ind].t) {
                                        history.push_back({history.back().f, end.desc[1]});
                                    } else {
                                        history.push_back({end.desc[0], history.back().g});
                                    }

                                }

                            }
                        }

                        // sonderfall
                        if (edge.size() > 1) {
                            StripPtR &a = edge.front(),
                                &b = *(edge.begin()+1);

                            if (a.ind == b.ind
                                && b.strip == start.strip
                                && pts[a.ind].capt == Capt::A) { // sollte weg

#ifdef DEBUG
                                std::cout << "~3 ref " << a.ref;
#endif

                                if (b.side == Side::START) {
                                    a.ref = b.desc[0];
                                } else {
                                    a.ref = b.desc[1];
                                }

#ifdef DEBUG
                                std::cout << " -> " << a.ref << " (from strip " << b.strip << ", ind " << b.ind << ")" << std::endl;
#endif

                            }
                        }

                    }

                    // doppelte punkte entfernen

                    double pt[3];

                    for (auto &newPoly : newPolys) {
                        IdsType _newPoly;

                        std::map<vtkIdType, Point3d> _pts;

                        for (vtkIdType id : newPoly) {
                            pd->GetPoint(id, pt);

                            _pts.emplace(std::piecewise_construct,
                                std::forward_as_tuple(id),
                                std::forward_as_tuple(pt[0], pt[1], pt[2]));
                        }

                        IdsType::const_iterator itrA, itrB;

                        for (itrA = newPoly.begin(); itrA != newPoly.end(); ++itrA) {
                            itrB = itrA+1;
                            if (itrB == newPoly.end()) {
                                itrB = newPoly.begin();
                            }

                            auto _a = _pts.find(*itrA);
                            auto _b = _pts.find(*itrB);

                            if (_a->second == _b->second) {
                                // doppelt
#ifdef DEBUG
                                std::cout << "removing " << *itrA << std::endl;
#endif
                            } else {
                                _newPoly.push_back(*itrA);
                            }
                        }

                        newPoly.swap(_newPoly);

                    }

                    // prüft, ob die erstellten polys gültig sind

                    if (newPolys[0].size() > 2) {
                        polys.push_back(newPolys[0]);
                    }

                    if (HasArea(strip) && newPolys[1].size() > 2) {
                        polys.push_back(newPolys[1]);
                    }

                    cycle = 0;

                    break;

                } else {
                    polys.push_back(next);

                    cycle++;
                }

            }

        }

        // erzeugte polys hinzufügen

        IdsType descIds;
        descIds.reserve(polys.size());

        for (auto &p : polys) {
            vtkIdList *cell = vtkIdList::New();

            for (vtkIdType &id : p) {
                cell->InsertNextId(id);
            }

            descIds.emplace_back(pd->InsertNextCell(VTK_POLYGON, cell));
            origCellIds->InsertNextValue(origId);

            cell->Delete();
        }

        pd->DeleteCell(polyInd);

        // holes einbauen
        if (!holes.empty()) {
            try {
                Merger(pd, pStrips, holes, descIds, origId).Run();
            } catch (const std::runtime_error &e) {
                return true;
            }
        }

    }

    pd->RemoveDeletedCells();
    pd->BuildCells();

    return false;

}

void vtkPolyDataBooleanFilter::RestoreOrigPoints (vtkPolyData *pd, PolyStripsType &polyStrips) {

#ifdef DEBUG
    std::cout << "RestoreOrigPoints()" << std::endl;
#endif

    pd->BuildLinks();

    vtkKdTreePointLocator *loc = vtkKdTreePointLocator::New();
    loc->SetDataSet(pd);
    loc->BuildLocator();

    struct Cmp {
        bool operator() (const StripPt &l, const StripPt &r) const {
            return l.ind < r.ind;
        }
    };

    PolyStripsType::const_iterator itr;
    StripPtsType::const_iterator itr2;

    std::set<std::reference_wrapper<const StripPt>, Cmp> ends;

    for (itr = polyStrips.begin(); itr != polyStrips.end(); ++itr) {
        const PStrips &pStrips = itr->second;

        for (itr2 = pStrips.pts.begin(); itr2 != pStrips.pts.end(); ++itr2) {
            const StripPt &sp = itr2->second;

            if (sp.capt != Capt::NOT) {
                ends.emplace(sp);
            }

        }
    }

    vtkIdList *pts = vtkIdList::New();

    vtkIdType i, numPts;

    for (const StripPt &sp : ends) {
        FindPoints(loc, sp.cutPt, pts);
        numPts = pts->GetNumberOfIds();

        for (i = 0; i < numPts; i++) {
            pd->GetPoints()->SetPoint(pts->GetId(i), sp.pt);
        }
    }

    pts->Delete();

    loc->FreeSearchStructure();
    loc->Delete();

}

void vtkPolyDataBooleanFilter::DisjoinPolys (vtkPolyData *pd, PolyStripsType &polyStrips) {

#ifdef DEBUG
    std::cout << "DisjoinPolys()" << std::endl;
#endif

    pd->BuildLinks();

    vtkKdTreePointLocator *loc = vtkKdTreePointLocator::New();
    loc->SetDataSet(pd);
    loc->BuildLocator();

    struct Cmp {
        bool operator() (const StripPt &l, const StripPt &r) const {
            return l.ind < r.ind;
        }
    };

    PolyStripsType::const_iterator itr;
    StripPtsType::const_iterator itr2;

    std::set<std::reference_wrapper<const StripPt>, Cmp> ends;

    for (itr = polyStrips.begin(); itr != polyStrips.end(); ++itr) {
        const PStrips &pStrips = itr->second;

        for (itr2 = pStrips.pts.begin(); itr2 != pStrips.pts.end(); ++itr2) {
            const StripPt &sp = itr2->second;

            if (sp.capt == Capt::A) {
                ends.emplace(sp);
            }
        }
    }

    vtkIdList *pts = vtkIdList::New();
    vtkIdList *cells = vtkIdList::New();

    vtkIdType i, j, numPts, numCells;

    for (const StripPt &sp : ends) {
        FindPoints(loc, sp.pt, pts);
        numPts = pts->GetNumberOfIds();

        for (i = 0; i < numPts; i++) {
            pd->GetPointCells(pts->GetId(i), cells);
            numCells = cells->GetNumberOfIds();

            if (numCells > 1) {
                for (j = 0; j < numCells; j++) {
                    pd->ReplaceCellPoint(cells->GetId(j), pts->GetId(i), pd->GetPoints()->InsertNextPoint(sp.pt));
                }
            }
        }
    }

    cells->Delete();
    pts->Delete();

    loc->FreeSearchStructure();
    loc->Delete();

}

void vtkPolyDataBooleanFilter::ResolveOverlaps (vtkPolyData *pd, vtkIdTypeArray *conts, PolyStripsType &polyStrips) {

#ifdef DEBUG
    std::cout << "ResolveOverlaps()" << std::endl;
#endif

    pd->BuildCells();
    pd->BuildLinks();

    contLines->BuildLinks();

    vtkKdTreePointLocator *loc = vtkKdTreePointLocator::New();
    loc->SetDataSet(pd);
    loc->BuildLocator();

    struct Cmp {
        bool operator() (const StripPt &l, const StripPt &r) const {
            return l.ind < r.ind;
        }
    };

    PolyStripsType::const_iterator itr;
    StripPtsType::const_iterator itr2;

    std::set<std::reference_wrapper<const StripPt>, Cmp> ends;

    for (itr = polyStrips.begin(); itr != polyStrips.end(); ++itr) {
        const PStrips &pStrips = itr->second;

        for (itr2 = pStrips.pts.begin(); itr2 != pStrips.pts.end(); ++itr2) {
            const StripPt &sp = itr2->second;

            if (sp.capt == Capt::EDGE) {
                ends.emplace(sp);
            }
        }
    }

    vtkIdList *links = vtkIdList::New(),
        *ptsA = vtkIdList::New(),
        *ptsB = vtkIdList::New(),
        *cells = vtkIdList::New(),
        *poly = vtkIdList::New();

    double ptA[3], ptB[3];

    vtkIdType i, j, k, numPtsA, numPtsB, numCells, numPts, idA, idB;

    std::map<Pair, IdsType> sharedPts;

    for (const StripPt &sp : ends) {
        contLines->GetPointCells(sp.ind, links);

        if (links->GetNumberOfIds() == 2
            && conts->GetValue(links->GetId(0)) != conts->GetValue(links->GetId(1))) {

            std::vector<Pair> history(sp.history.rbegin(), sp.history.rend());

            for (const Pair &p : history) {
                pd->GetPoint(p.f, ptA);
                pd->GetPoint(p.g, ptB);

                FindPoints(loc, ptA, ptsA);
                FindPoints(loc, ptB, ptsB);

                numPtsA = ptsA->GetNumberOfIds();
                numPtsB = ptsB->GetNumberOfIds();

                std::vector<Pair> cellsA, cellsB;

                for (i = 0; i < numPtsA; i++) {
                    pd->GetPointCells(ptsA->GetId(i), cells);
                    numCells = cells->GetNumberOfIds();

                    for (j = 0; j < numCells; j++) {
                        cellsA.emplace_back(ptsA->GetId(i), cells->GetId(j));
                    }
                }

                for (i = 0; i < numPtsB; i++) {
                    pd->GetPointCells(ptsB->GetId(i), cells);
                    numCells = cells->GetNumberOfIds();

                    for (j = 0; j < numCells; j++) {
                        cellsB.emplace_back(ptsB->GetId(i), cells->GetId(j));
                    }
                }

                for (auto &cellA : cellsA) {
                    for (auto &cellB : cellsB) {
                        if (cellA.g == cellB.g) {
                            // kante/poly existiert noch

                            pd->GetCellPoints(cellA.g, poly);
                            numPts = poly->GetNumberOfIds();

                            for (k = 0; k < numPts; k++) {
                                idA = poly->GetId(k);
                                idB = k+1 == numPts ? poly->GetId(0) : poly->GetId(k+1);

                                if (cellB.f == idA
                                    && cellA.f == idB) {

                                    IdsType &pts = sharedPts[Pair{sp.ind, cellA.g}];

                                    pts.push_back(cellA.f);
                                    pts.push_back(cellB.f);

                                    break;
                                }
                            }

                        }
                    }
                }


            }

        }
    }

    double pt[3];

    decltype(sharedPts)::iterator itr3;

    for (itr3 = sharedPts.begin(); itr3 != sharedPts.end(); ++itr3) {
        const Pair &p = itr3->first;

        IdsType &pts = itr3->second;

        std::sort(pts.begin(), pts.end());

        auto found = std::adjacent_find(pts.begin(), pts.end());

        if (found != pts.end()) {
            contLines->GetPoint(p.f, pt);

            i = pd->GetPoints()->InsertNextPoint(pt);
            pd->ReplaceCellPoint(p.g, *found, i);
        }
    }

    links->Delete();
    ptsA->Delete();
    ptsB->Delete();
    cells->Delete();
    poly->Delete();

    loc->FreeSearchStructure();
    loc->Delete();

}

void vtkPolyDataBooleanFilter::AddAdjacentPoints (vtkPolyData *pd, vtkIdTypeArray *conts, PolyStripsType &polyStrips) {

#ifdef DEBUG
    std::cout << "AddAdjacentPoints()" << std::endl;
#endif

    pd->BuildLinks();

    vtkIdTypeArray *origCellIds = vtkIdTypeArray::SafeDownCast(pd->GetCellData()->GetScalars("OrigCellIds"));

    struct Cmp {
        bool operator() (const StripPt &l, const StripPt &r) const {
            return l.t < r.t;
        }
    };

    vtkKdTreePointLocator *loc = vtkKdTreePointLocator::New();
    loc->SetDataSet(pd);
    loc->BuildLocator();

    vtkIdList *cells = vtkIdList::New(),
        *ptsA = vtkIdList::New(),
        *ptsB = vtkIdList::New(),
        *poly = vtkIdList::New(),
        *newPoly = vtkIdList::New();

    vtkIdType i, j, numCells, numPtsA, numPtsB, numPts, idA, idB;

    PolyStripsType::const_iterator itr;
    StripPtsType::const_iterator itr2;

    for (itr = polyStrips.begin(); itr != polyStrips.end(); ++itr) {
        const PStrips &pStrips = itr->second;

        std::map<Pair, std::set<std::reference_wrapper<const StripPt>, Cmp>> edgePts;

        for (itr2 = pStrips.pts.begin(); itr2 != pStrips.pts.end(); ++itr2) {
            const StripPt &sp = itr2->second;

            if (sp.capt == Capt::EDGE) {
                edgePts[{sp.edge[0], sp.edge[1]}].emplace(sp);
            }
        }

        decltype(edgePts)::iterator itr3;

        for (itr3 = edgePts.begin(); itr3 != edgePts.end(); ++itr3) {
            const Pair &edge = itr3->first;
            auto pts = itr3->second;

            StripPt spA, spB;

            pd->GetPoint(edge.f, spA.pt);
            pd->GetPoint(edge.g, spB.pt);

            spA.t = 0;
            spB.t = 1;

            pts.emplace(spA);
            pts.emplace(spB);

            std::vector<decltype(pts)::value_type> _pts(pts.rbegin(), pts.rend());

            decltype(_pts)::const_iterator itrA, itrB, itrC;

            itrA = _pts.begin();

            while (itrA != _pts.end()-1) {
                itrB = itrA+1;

                while (itrB != _pts.end()-1) {
                    contLines->GetPointCells(itrB->get().ind, cells);
                    numCells = cells->GetNumberOfIds();

                    // std::cout << "[";
                    // for (i = 0; i < numCells; i++) {
                    //     std::cout << conts->GetValue(cells->GetId(i)) << ", ";
                    // }
                    // std::cout << "]" << std::endl;

                    // break;

                    ++itrB;
                }

                if (std::distance(itrA, itrB) > 1) {
                    FindPoints(loc, itrA->get().pt, ptsA);
                    FindPoints(loc, itrB->get().pt, ptsB);

                    numPtsA = ptsA->GetNumberOfIds();
                    numPtsB = ptsB->GetNumberOfIds();

                    std::vector<Pair> polysA, polysB;

                    for (i = 0; i < numPtsA; i++) {
                        pd->GetPointCells(ptsA->GetId(i), cells);
                        numCells = cells->GetNumberOfIds();

                        for (j = 0; j < numCells; j++) {
                            polysA.emplace_back(cells->GetId(j), ptsA->GetId(i));
                        }
                    }

                    for (i = 0; i < numPtsB; i++) {
                        pd->GetPointCells(ptsB->GetId(i), cells);
                        numCells = cells->GetNumberOfIds();

                        for (j = 0; j < numCells; j++) {
                            polysB.emplace_back(cells->GetId(j), ptsB->GetId(i));
                        }
                    }

                    /*for (const Pair &pA : polysA) {
                        std::cout << "pA " << pA << std::endl;
                    }

                    for (const Pair &pB : polysB) {
                        std::cout << "pB " << pB << std::endl;
                    }*/

                    for (const Pair &pA : polysA) {
                        for (const Pair &pB : polysB) {
                            if (pA.f == pB.f && pd->GetCellType(pA.f) != VTK_EMPTY_CELL) {

                                pd->GetCellPoints(pA.f, poly);
                                numPts = poly->GetNumberOfIds();

                                newPoly->Reset();

                                for (j = 0; j < numPts; j++) {
                                    newPoly->InsertNextId(poly->GetId(j));

                                    idA = poly->GetId(j);
                                    idB = j+1 == numPts ? poly->GetId(0) : poly->GetId(j+1);

                                    if (pA.g == idA
                                        && pB.g == idB) {

                                        for (itrC = itrA+1; itrC != itrB; ++itrC) {
                                            // newPoly->InsertNextId(pd->InsertNextLinkedPoint(itrC->get().pt, 1));

                                            pd->InsertNextLinkedPoint(1);

                                            newPoly->InsertNextId(pd->GetPoints()->InsertNextPoint(itrC->get().pt));
                                        }

                                    }

                                    pd->RemoveReferenceToCell(idA, pA.f);
                                }

                                pd->DeleteCell(pA.f);

                                pd->InsertNextLinkedCell(VTK_POLYGON, newPoly->GetNumberOfIds(), newPoly->GetPointer(0));

                                origCellIds->InsertNextValue(origCellIds->GetValue(pA.f));

                                break;
                            }
                        }
                    }
                }

                itrA = itrB;
            }
        }
    }

    cells->Delete();
    ptsA->Delete();
    ptsB->Delete();
    poly->Delete();
    newPoly->Delete();

    loc->FreeSearchStructure();
    loc->Delete();

    pd->RemoveDeletedCells();

}

void vtkPolyDataBooleanFilter::MergePoints (vtkPolyData *pd, PolyStripsType &polyStrips) {

#ifdef DEBUG
    std::cout << "MergePoints()" << std::endl;
#endif

    pd->BuildCells();
    pd->BuildLinks();

    contLines->BuildLinks();

    vtkKdTreePointLocator *loc = vtkKdTreePointLocator::New();
    loc->SetDataSet(pd);
    loc->BuildLocator();

    PolyStripsType::const_iterator itr;
    StripsType::const_iterator itr2;

    std::map<vtkIdType, std::set<vtkIdType>> neighPts;

    vtkIdList *pts = vtkIdList::New();

    vtkIdType i, j, numPts;

    for (itr = polyStrips.begin(); itr != polyStrips.end(); ++itr) {
        const PStrips &pStrips = itr->second;

        for (itr2 = pStrips.strips.begin(); itr2 != pStrips.strips.end(); ++itr2) {
            const StripType &strip = *itr2;

            const StripPtR &spA = strip.front(),
                &spB = strip.back();

            const auto beforeA = pStrips.pts.find((strip.begin()+1)->ind),
                beforeB = pStrips.pts.find((strip.end()-2)->ind);

            FindPoints(loc, beforeA->second.pt, pts);
            numPts = pts->GetNumberOfIds();

            for (i = 0; i < numPts; i++) {
                neighPts[spA.ind].insert(pts->GetId(i));
            }

            FindPoints(loc, beforeB->second.pt, pts);
            numPts = pts->GetNumberOfIds();

            for (i = 0; i < numPts; i++) {
                neighPts[spB.ind].insert(pts->GetId(i));
            }
        }
    }

    double pt[3];

    vtkIdList *polys = vtkIdList::New(),
        *poly = vtkIdList::New();

    vtkIdType ind, polyId, _numPts, before, after;

    decltype(neighPts)::const_iterator itr3;

    for (itr3 = neighPts.begin(); itr3 != neighPts.end(); ++itr3) {
        const auto &inds = itr3->second;

        std::map<Point3d, std::vector<Pair>> pairs;

        contLines->GetPoint(itr3->first, pt);

        FindPoints(loc, pt, pts);
        numPts = pts->GetNumberOfIds();

        for (i = 0; i < numPts; i++) {
            ind = pts->GetId(i);

            pd->GetPointCells(ind, polys);

            if (polys->GetNumberOfIds() > 0) {
                polyId = polys->GetId(0);

                pd->GetCellPoints(polyId, poly);
                _numPts = poly->GetNumberOfIds();

                for (j = 0; j < _numPts; j++) {
                    if (poly->GetId(j) == ind) {
                        break;
                    }
                }

                // wieder davor und danach ermitteln

                before = poly->GetId(j == 0 ? _numPts-1 : j-1);
                after = poly->GetId(j+1 == _numPts ? 0 : j+1);

                if (std::find(inds.begin(), inds.end(), before) == inds.end()) {
                    pd->GetPoint(before, pt);
                    pairs[{pt[0], pt[1], pt[2]}].emplace_back(polyId, ind);
                }

                if (std::find(inds.begin(), inds.end(), after) == inds.end()) {
                    pd->GetPoint(after, pt);
                    pairs[{pt[0], pt[1], pt[2]}].emplace_back(polyId, ind);
                }

            }
        }

        std::deque<std::deque<std::reference_wrapper<const Pair>>> Pairs;

        decltype(pairs)::const_iterator itr4;

        for (itr4 = pairs.begin(); itr4 != pairs.end(); ++itr4) {
            const auto &p = itr4->second;

            if (p.size() == 2) {
                auto _pts = {std::ref(p.front()), std::ref(p.back())}; // std::initializer_list
                Pairs.emplace_back(_pts);
            }
        }

        decltype(Pairs)::iterator itr5;

        /*for (itr5 = Pairs.begin(); itr5 != Pairs.end(); ++itr5) {
            for (auto &p : *itr5) {
                std::cout << p.get() << ", ";
            }
            std::cout << std::endl;
        }*/

        decltype(Pairs)::value_type group;

        decltype(group)::const_iterator itr6;

        while (!Pairs.empty()) {
            if (group.empty()) {
                group = Pairs.front();
                Pairs.pop_front();
            }

            itr5 = Pairs.begin();

            while (itr5 != Pairs.end()) {
                const auto &next = *itr5;

                if (next.front().get() == group.front().get()) {
                    group.emplace_front(next.back());
                    Pairs.erase(itr5);
                    itr5 = Pairs.begin();
                } else if (next.front().get() == group.back().get()) {
                    group.emplace_back(next.back());
                    Pairs.erase(itr5);
                    itr5 = Pairs.begin();
                } else if (next.back().get() == group.front().get()) {
                    group.emplace_front(next.front());
                    Pairs.erase(itr5);
                    itr5 = Pairs.begin();
                } else if (next.back().get() == group.back().get()) {
                    group.emplace_back(next.front());
                    Pairs.erase(itr5);
                    itr5 = Pairs.begin();
                } else {
                    ++itr5;
                }
            }

            if (itr5 == Pairs.end()) {
                for (itr6 = group.begin()+1; itr6 != group.end(); ++itr6) {
                    pd->ReplaceCellPoint(itr6->get().f, itr6->get().g, group.front().get().g);
                }

                group.clear();
            }
        }

    }

    polys->Delete();
    poly->Delete();
    pts->Delete();

    loc->FreeSearchStructure();
    loc->Delete();

}

enum class Congr {
    EQUAL,
    OPPOSITE,
    NOT
};

class PolyAtEdge {
    vtkPolyData *pd;

public:
    PolyAtEdge (vtkPolyData *_pd, vtkIdType _polyId, vtkIdType _ptIdA, vtkIdType _ptIdB) : pd(_pd), polyId(_polyId), ptIdA(_ptIdA), ptIdB(_ptIdB), loc(Loc::NONE) {

        double ptA[3], ptB[3];

        pd->GetPoint(ptIdA, ptA);
        pd->GetPoint(ptIdB, ptB);

        vtkMath::Subtract(ptB, ptA, e);
        vtkMath::Normalize(e);

        const vtkIdType *poly;

        vtkIdType numPts;
        pd->GetCellPoints(polyId, numPts, poly);

        ComputeNormal(pd->GetPoints(), n, numPts, poly);

        vtkMath::Cross(e, n, r);

    }

    vtkIdType polyId, ptIdA, ptIdB;
    double n[3], e[3], r[3];

    Loc loc;

    friend std::ostream& operator<< (std::ostream &out, const PolyAtEdge &p) {
        out << "polyId " << p.polyId << ", ptIdA " << p.ptIdA << ", ptIdB " << p.ptIdB;
        return out;
    }

    static constexpr double eps {.99999999}; // ~.0081deg

    Congr IsCongruent (const PolyAtEdge &p) const {
        double cong = vtkMath::Dot(n, p.n);

        if (cong > eps || cong < -eps) {
            double ang = vtkMath::Dot(r, p.r);

            if (ang > eps) {
                if (cong > eps) {
                    // normalen sind gleich ausgerichtet
                    return Congr::EQUAL;
                } else {
                    return Congr::OPPOSITE;
                }
            }
        }

        return Congr::NOT;
    }

};


class PolyPair {
public:
    PolyPair (PolyAtEdge _pA, PolyAtEdge _pB) : pA(_pA), pB(_pB) {}

    PolyAtEdge pA, pB;

    void GetLoc (PolyAtEdge &pT, vtkIdType mode) {

        Congr cA = pA.IsCongruent(pT),
            cB = pB.IsCongruent(pT);

#ifdef DEBUG
        std::cout << "GetLoc() -> polyId " << pT.polyId
                  << ", cA " << cA
                  << ", cB " << cB
                  << std::endl;

        if (cA != Congr::NOT || cB != Congr::NOT) {
            assert(cA != cB);
        }

#endif

        if (cA == Congr::EQUAL || cA == Congr::OPPOSITE) {
            if (cA == Congr::OPPOSITE) {
                // normalen sind entgegengesetzt gerichtet

                if (mode == OPER_INTERSECTION) {
                    pA.loc = Loc::OUTSIDE;
                    pT.loc = Loc::OUTSIDE;
                } else {
                    pA.loc = Loc::INSIDE;
                    pT.loc = Loc::INSIDE;
                }
            } else if (mode == OPER_UNION || mode == OPER_INTERSECTION) {
                pA.loc = Loc::INSIDE;
                pT.loc = Loc::OUTSIDE;
            }

        } else if (cB == Congr::EQUAL || cB == Congr::OPPOSITE) {
            if (cB == Congr::OPPOSITE) {
                // normalen sind entgegengesetzt gerichtet

                if (mode == OPER_INTERSECTION) {
                    pB.loc = Loc::OUTSIDE;
                    pT.loc = Loc::OUTSIDE;
                } else {
                    pB.loc = Loc::INSIDE;
                    pT.loc = Loc::INSIDE;
                }
            } else if (mode == OPER_UNION || mode == OPER_INTERSECTION) {
                pB.loc = Loc::INSIDE;
                pT.loc = Loc::OUTSIDE;
            }

        } else {
            double alpha = GetAngle(pA.r, pB.r, pA.e),
                beta = GetAngle(pA.r, pT.r, pA.e);

            if (beta > alpha) {
                pT.loc = Loc::INSIDE;
            } else {
                pT.loc = Loc::OUTSIDE;
            }
        }
    }

};


std::shared_ptr<PolyPair> GetEdgePolys (vtkPolyData *pd, vtkIdList *ptsA, vtkIdList *ptsB) {

#ifdef DEBUG
    std::cout << "GetEdgePolys()" << std::endl;
#endif

    std::vector<Pair> p;

    vtkIdType numPtsA = ptsA->GetNumberOfIds(),
        numPtsB = ptsB->GetNumberOfIds();

    vtkIdList *polys = vtkIdList::New();

    vtkIdType i, j, numCells;

    for (i = 0; i < numPtsA; i++) {
        pd->GetPointCells(ptsA->GetId(i), polys);
        numCells = polys->GetNumberOfIds();

        for (j = 0; j < numCells; j++) {
            p.emplace_back(ptsA->GetId(i), polys->GetId(j));
        }
    }

    for (i = 0; i < numPtsB; i++) {
        pd->GetPointCells(ptsB->GetId(i), polys);
        numCells = polys->GetNumberOfIds();

        for (j = 0; j < numCells; j++) {
            p.emplace_back(ptsB->GetId(i), polys->GetId(j));
        }
    }

    polys->Delete();

    std::map<vtkIdType, IdsType> pEdges;

    std::vector<Pair>::const_iterator itr;
    for (itr = p.begin(); itr != p.end(); ++itr) {
        pEdges[itr->g].push_back(itr->f);
    }

    std::vector<PolyAtEdge> opp;

    vtkIdList *poly = vtkIdList::New();

    vtkIdType numPts, a, b;

    std::map<vtkIdType, IdsType>::const_iterator itr2;

    for (itr2 = pEdges.begin(); itr2 != pEdges.end(); ++itr2) {
        const IdsType &pts = itr2->second;

        if (pts.size() > 1) {
            pd->GetCellPoints(itr2->first, poly);
            numPts = poly->GetNumberOfIds();

            for (i = 0; i < numPts; i++) {
                a = poly->GetId(i);
                b = i+1 == numPts ? poly->GetId(0) : poly->GetId(i+1);

                if (std::find(pts.begin(), pts.end(), a) != pts.end()
                    && std::find(pts.begin(), pts.end(), b) != pts.end()) {

                    opp.emplace_back(pd, itr2->first, a, b);
                }
            }

        }
    }

    poly->Delete();

#ifdef DEBUG
    for (auto &op : opp) {
        std::cout << op << std::endl;
    }
#endif

    if (opp.size() != 2) {
        return nullptr;
    }

    return std::make_shared<PolyPair>(opp[0], opp[1]);

}

bool vtkPolyDataBooleanFilter::CombineRegions () {

#ifdef DEBUG
    std::cout << "CombineRegions()" << std::endl;
#endif

    vtkSmartPointer<vtkPolyData> filterdA = vtkSmartPointer<vtkPolyData>::New();
    filterdA->DeepCopy(modPdA);

    vtkSmartPointer<vtkPolyData> filterdB = vtkSmartPointer<vtkPolyData>::New();
    filterdB->DeepCopy(modPdB);

    // ungenutzte punkte löschen
    vtkSmartPointer<vtkCleanPolyData> cleanA = vtkSmartPointer<vtkCleanPolyData>::New();
    cleanA->PointMergingOff();
    cleanA->SetInputData(filterdA);

    vtkSmartPointer<vtkCleanPolyData> cleanB = vtkSmartPointer<vtkCleanPolyData>::New();
    cleanB->PointMergingOff();
    cleanB->SetInputData(filterdB);

    // regionen mit skalaren ausstatten
    vtkSmartPointer<vtkPolyDataConnectivityFilter> cfA = vtkSmartPointer<vtkPolyDataConnectivityFilter>::New();
    cfA->SetExtractionModeToAllRegions();
    cfA->ColorRegionsOn();
    cfA->SetInputConnection(cleanA->GetOutputPort());

    vtkSmartPointer<vtkPolyDataConnectivityFilter> cfB = vtkSmartPointer<vtkPolyDataConnectivityFilter>::New();
    cfB->SetExtractionModeToAllRegions();
    cfB->ColorRegionsOn();
    cfB->SetInputConnection(cleanB->GetOutputPort());

    cfA->Update();
    cfB->Update();

    vtkPolyData *pdA = cfA->GetOutput();
    vtkPolyData *pdB = cfB->GetOutput();

#ifdef DEBUG
    std::cout << "Exporting modPdA_8.vtk" << std::endl;
    WriteVTK("modPdA_8.vtk", pdA);

    std::cout << "Exporting modPdB_8.vtk" << std::endl;
    WriteVTK("modPdB_8.vtk", pdB);
#endif

    resultC->ShallowCopy(contLines);

    if (OperMode == OPER_NONE) {
        resultA->ShallowCopy(pdA);
        resultB->ShallowCopy(pdB);

        return false;
    }

    vtkSmartPointer<vtkKdTreePointLocator> plA = vtkSmartPointer<vtkKdTreePointLocator>::New();
    plA->SetDataSet(pdA);
    plA->BuildLocator();

    vtkSmartPointer<vtkKdTreePointLocator> plB = vtkSmartPointer<vtkKdTreePointLocator>::New();
    plB->SetDataSet(pdB);
    plB->BuildLocator();

    pdA->BuildLinks();
    pdB->BuildLinks();

    vtkIdTypeArray *scalarsA = vtkIdTypeArray::SafeDownCast(pdA->GetPointData()->GetScalars());
    vtkIdTypeArray *scalarsB = vtkIdTypeArray::SafeDownCast(pdB->GetPointData()->GetScalars());

    vtkSmartPointer<vtkIdList> line = vtkSmartPointer<vtkIdList>::New();

    double ptA[3], ptB[3];

    vtkSmartPointer<vtkIdList> fptsA = vtkSmartPointer<vtkIdList>::New();
    vtkSmartPointer<vtkIdList> lptsA = vtkSmartPointer<vtkIdList>::New();

    vtkSmartPointer<vtkIdList> fptsB = vtkSmartPointer<vtkIdList>::New();
    vtkSmartPointer<vtkIdList> lptsB = vtkSmartPointer<vtkIdList>::New();

    std::map<vtkIdType, Loc> locsA, locsB;

    vtkIdType i, j, numLines = contLines->GetNumberOfCells();

    IdsType _failed;

    for (i = 0; i < numLines; i++) {

        if (contLines->GetCellType(i) == VTK_EMPTY_CELL) {
            continue;
        }

        contLines->GetCellPoints(i, line);

        contLines->GetPoint(line->GetId(0), ptA);
        contLines->GetPoint(line->GetId(1), ptB);

        FindPoints(plA, ptA, fptsA);
        FindPoints(plB, ptA, fptsB);

#ifdef DEBUG
        std::cout << "line " << i << std::endl;
#else

        // bereits behandelte regionen werden nicht noch einmal untersucht

        vtkIdType notLocated = 0;

        for (j = 0; j < fptsA->GetNumberOfIds(); j++) {
            if (locsA.count(scalarsA->GetValue(fptsA->GetId(j))) == 0) {
                notLocated++;
            }
        }

        for (j = 0; j < fptsB->GetNumberOfIds(); j++) {
            if (locsB.count(scalarsB->GetValue(fptsB->GetId(j))) == 0) {
                notLocated++;
            }
        }

        if (notLocated == 0) {
            continue;
        }

#endif

        FindPoints(plA, ptB, lptsA);
        FindPoints(plB, ptB, lptsB);

        auto ppA = GetEdgePolys(pdA, fptsA, lptsA);
        auto ppB = GetEdgePolys(pdB, fptsB, lptsB);

        if (ppA && ppB) {

            ppB->GetLoc(ppA->pA, OperMode);
            ppB->GetLoc(ppA->pB, OperMode);

            ppA->GetLoc(ppB->pA, OperMode);
            ppA->GetLoc(ppB->pB, OperMode);

            vtkIdType fsA = scalarsA->GetValue(ppA->pA.ptIdA);
            vtkIdType lsA = scalarsA->GetValue(ppA->pB.ptIdA);

            vtkIdType fsB = scalarsB->GetValue(ppB->pA.ptIdA);
            vtkIdType lsB = scalarsB->GetValue(ppB->pB.ptIdA);

#ifdef DEBUG
            std::cout << "polyId " << ppA->pA.polyId << ", sA " << fsA << ", loc " << ppA->pA.loc << std::endl;
            std::cout << "polyId " << ppA->pB.polyId << ", sA " << lsA << ", loc " << ppA->pB.loc << std::endl;
            std::cout << "polyId " << ppB->pA.polyId << ", sB " << fsB << ", loc " << ppB->pA.loc << std::endl;
            std::cout << "polyId " << ppB->pB.polyId << ", sB " << lsB << ", loc " << ppB->pB.loc << std::endl;

            if (locsA.count(fsA) > 0 && locsA[fsA] != ppA->pA.loc) {
                std::cout << "sA " << fsA << ": " << locsA[fsA] << " -> " << ppA->pA.loc << std::endl;
            }

            if (locsA.count(lsA) > 0 && locsA[lsA] != ppA->pB.loc) {
                std::cout << "sA " << lsA << ": " << locsA[lsA] << " -> " << ppA->pB.loc << std::endl;
            }

            if (locsB.count(fsB) > 0 && locsB[fsB] != ppB->pA.loc) {
                std::cout << "sB " << fsB << ": " << locsB[fsB] << " -> " << ppB->pA.loc << std::endl;
            }

            if (locsB.count(lsB) > 0 && locsB[lsB] != ppB->pB.loc) {
                std::cout << "sB " << lsB << ": " << locsB[lsB] << " -> " << ppB->pB.loc << std::endl;
            }

#endif

            locsA.emplace(fsA, ppA->pA.loc);
            locsA.emplace(lsA, ppA->pB.loc);

            locsB.emplace(fsB, ppB->pA.loc);
            locsB.emplace(lsB, ppB->pB.loc);

        } else {
            _failed.push_back(i);

            // return true;
        }

    }

    if (_failed.size() > 0) {
        for (auto i : _failed) {
            std::cout << "failed at " << i
                << std::endl;
        }

        return true;
    }

    // reale kombination der ermittelten regionen

    Loc comb[] = {Loc::OUTSIDE, Loc::OUTSIDE};

    if (OperMode == OPER_INTERSECTION) {
        comb[0] = Loc::INSIDE;
        comb[1] = Loc::INSIDE;
    } else if (OperMode == OPER_DIFFERENCE) {
        comb[1] = Loc::INSIDE;
    } else if (OperMode == OPER_DIFFERENCE2) {
        comb[0] = Loc::INSIDE;
    }

    vtkIdType numA = cfA->GetNumberOfExtractedRegions(),
        numB = cfB->GetNumberOfExtractedRegions();

    cfA->SetExtractionModeToSpecifiedRegions();
    cfB->SetExtractionModeToSpecifiedRegions();

    std::map<vtkIdType, Loc>::const_iterator itr;

    for (itr = locsA.begin(); itr != locsA.end(); itr++) {
        if (itr->second == comb[0]) {
            cfA->AddSpecifiedRegion(itr->first);
        }
    }

    for (itr = locsB.begin(); itr != locsB.end(); itr++) {
        if (itr->second == comb[1]) {
            cfB->AddSpecifiedRegion(itr->first);
        }
    }

    // nicht beteiligte regionen hinzufügen

    if (OperMode == OPER_UNION || OperMode == OPER_DIFFERENCE) {
        for (i = 0; i < numA; i++) {
            if (locsA.count(i) == 0) {
                cfA->AddSpecifiedRegion(i);
            }
        }
    }

    if (OperMode == OPER_UNION || OperMode == OPER_DIFFERENCE2) {
        for (i = 0; i < numB; i++) {
            if (locsB.count(i) == 0) {
                cfB->AddSpecifiedRegion(i);
            }
        }
    }

    // nach innen zeigende normalen umkehren

    cfA->Update();
    cfB->Update();

    vtkPolyData *regsA = cfA->GetOutput();
    vtkPolyData *regsB = cfB->GetOutput();

    scalarsA = vtkIdTypeArray::SafeDownCast(regsA->GetPointData()->GetScalars());
    scalarsB = vtkIdTypeArray::SafeDownCast(regsB->GetPointData()->GetScalars());

    if (OperMode != OPER_INTERSECTION) {
        if (comb[0] == Loc::INSIDE) {
            for (i = 0; i < regsA->GetNumberOfCells(); i++) {
                if (locsA.count(scalarsA->GetValue(i)) == 1) {
                    regsA->ReverseCell(i);
                }
            }
        }

        if (comb[1] == Loc::INSIDE) {
            for (i = 0; i < regsB->GetNumberOfCells(); i++) {
                if (locsB.count(scalarsB->GetValue(i)) == 1) {
                    regsB->ReverseCell(i);
                }
            }
        }
    }

    // OrigCellIds und CellData

    vtkIdTypeArray *origCellIdsA = vtkIdTypeArray::SafeDownCast(regsA->GetCellData()->GetScalars("OrigCellIds"));
    vtkIdTypeArray *origCellIdsB = vtkIdTypeArray::SafeDownCast(regsB->GetCellData()->GetScalars("OrigCellIds"));

    vtkIdTypeArray *newOrigCellIdsA = vtkIdTypeArray::New();
    newOrigCellIdsA->SetName("OrigCellIdsA");

    vtkIdTypeArray *newOrigCellIdsB = vtkIdTypeArray::New();
    newOrigCellIdsB->SetName("OrigCellIdsB");

    vtkCellData *newCellDataA = vtkCellData::New();
    newCellDataA->CopyAllocate(cellDataA);

    vtkCellData *newCellDataB = vtkCellData::New();
    newCellDataB->CopyAllocate(cellDataB);

    vtkIdType cellId;

    for (i = 0; i < regsA->GetNumberOfCells(); i++) {
        cellId = cellIdsA->GetValue(origCellIdsA->GetValue(i));

        newOrigCellIdsA->InsertNextValue(cellId);
        newOrigCellIdsB->InsertNextValue(-1);

        newCellDataA->CopyData(cellDataA, cellId, i);
    }

    for (i = 0; i < regsB->GetNumberOfCells(); i++) {
        cellId = cellIdsB->GetValue(origCellIdsB->GetValue(i));

        newOrigCellIdsB->InsertNextValue(cellId);
        newOrigCellIdsA->InsertNextValue(-1);

        newCellDataB->CopyData(cellDataB, cellId, i);
    }

    regsA->GetCellData()->Initialize();
    regsB->GetCellData()->Initialize();

    regsA->GetCellData()->ShallowCopy(newCellDataA);
    regsB->GetCellData()->ShallowCopy(newCellDataB);

    newCellDataA->Delete();
    newCellDataB->Delete();

    // zusammenführung

    vtkAppendPolyData *app = vtkAppendPolyData::New();
    app->AddInputData(regsA);
    app->AddInputData(regsB);

    // entfernt ungenutzte punkte
    vtkCleanPolyData *cleanApp = vtkCleanPolyData::New();
    cleanApp->PointMergingOff();
    cleanApp->SetInputConnection(app->GetOutputPort());

    // färbt die regionen nochmal neu ein, damit mehrere regionen nicht die gleiche farbe haben

    vtkPolyDataConnectivityFilter *cfApp = vtkPolyDataConnectivityFilter::New();
    cfApp->SetExtractionModeToAllRegions();
    cfApp->ColorRegionsOn();
    cfApp->SetInputConnection(cleanApp->GetOutputPort());

    cfApp->Update();

    vtkPolyData *cfPd = cfApp->GetOutput();

    // resultB bleibt hier leer

    resultA->ShallowCopy(cfPd);

    resultA->GetCellData()->AddArray(newOrigCellIdsA);
    resultA->GetCellData()->AddArray(newOrigCellIdsB);

    // aufräumen

    cfApp->Delete();
    cleanApp->Delete();
    app->Delete();

    newOrigCellIdsB->Delete();
    newOrigCellIdsA->Delete();

    plB->FreeSearchStructure();
    plA->FreeSearchStructure();

    return false;

}

Merger::Merger (vtkPolyData *pd, const PStrips &pStrips, const StripsType &strips, const IdsType &descIds, vtkIdType origId) : pd(pd), pStrips(pStrips), origId(origId) {

    const StripPtsType &pts = pStrips.pts;
    const Base &base = pStrips.base;

    vtkIdType i, num;
    const vtkIdType *cell;

    double pt[3];

    for (auto id : descIds) {
        pd->GetCellPoints(id, num, cell);

        Poly p;

        for (i = 0; i < num; i++) {
            pd->GetPoint(cell[i], pt);

            double proj[2];
            Transform(pt, proj, base);

            p.emplace_back(proj[0], proj[1], 0, cell[i]);

        }

        polys.push_back(p);

        pd->DeleteCell(id);
    }

    for (auto &strip : strips) {
        Poly p;

        for (auto &sp : strip) {
            const double *pt = pts.at(sp.ind).pt;

            double proj[2];
            Transform(pt, proj, base);

            p.emplace_back(proj[0], proj[1], 0);
        }

        p.pop_back();

        double n[3];
        ComputeNormal(p, n);

        if (n[2] < 0) {
            Poly q(p.rbegin(), p.rend());
            p.swap(q);
        }

        polys.push_back(p);
    }

}

void Merger::Run () {
    // mergen mit hilfe von vtkKdTree und vtkModifiedBSPTree

    vtkPoints *pdPts = pd->GetPoints();
    vtkIdTypeArray *origCellIds = vtkIdTypeArray::SafeDownCast(pd->GetCellData()->GetScalars("OrigCellIds"));

    assert(origCellIds != nullptr);

    const Base &base = pStrips.base;

    std::vector<GroupType> groups(polys.size());

    PolysType::const_iterator itrA, itrB;

    for (itrA = polys.begin(); itrA != polys.end(); ++itrA) {
        for (itrB = polys.begin(); itrB != polys.end(); ++itrB) {
            if (itrA != itrB && PointInPoly(*itrB, *itrA->begin())) {
                groups[static_cast<std::size_t>(itrB-polys.begin())].push_back(static_cast<std::size_t>(itrA-polys.begin()));
            }
        }
    }

    std::size_t parent = 0;

    for (auto &group : groups) {
        GroupType parents;

        for (auto &index : group) {
            const GroupType &_group = groups[index];
            parents.insert(parents.end(), _group.begin(), _group.end());
        }

        std::sort(group.begin(), group.end());
        std::sort(parents.begin(), parents.end());

        GroupType _group {parent++};
        std::set_difference(group.begin(), group.end(), parents.begin(), parents.end(), std::back_inserter(_group));

        std::cout << "[";
        for (auto &index : _group) {
            std::cout << index << ", ";
        }
        std::cout << "]" << std::endl;

        PolysType merged;

        MergeGroup(_group, merged);

        std::map<Point3d, vtkIdType> newIds;

        for (auto &poly : merged) {
            vtkSmartPointer<vtkIdList> newCell = vtkSmartPointer<vtkIdList>::New();

            for (auto &p : poly) {
                double in[] = {p.x, p.y},
                    out[3];

                BackTransform(in, out, base);

                vtkIdType id = p.id;

                if (id == NOTSET) {
                    auto itr = newIds.find(p);

                    if (itr == newIds.end()) {
                        id = pdPts->InsertNextPoint(out);
                        newIds.emplace(p, id);
                    } else {
                        id = itr->second;
                    }
                }

                newCell->InsertNextId(id);

            }

            pd->InsertNextCell(VTK_POLYGON, newCell);
            origCellIds->InsertNextValue(origId);
        }

    }

}

void Merger::MergeGroup (const GroupType &group, PolysType &merged) {
    if (group.size() == 1) {
        merged.push_back(polys.at(group.back()));

        return;
    }

    vtkSmartPointer<vtkPoints> pts = vtkSmartPointer<vtkPoints>::New();

    IndexedPolysType indexedPolys;

    ReferencedPointsType refPts;

    SourcesType sources;
    std::size_t src = 0;

    for (auto &index : group) {
        const Poly &poly = polys.at(index);

        IndexedPoly ids;

        for (auto &p : poly) {
            vtkIdType id = pts->InsertNextPoint(p.x, p.y, p.z);

            ids.push_back(id);
            sources.emplace(id, src);

            refPts.emplace(id, p);
        }

        indexedPolys.push_back(std::move(ids));
        src++;
    }

    vtkSmartPointer<vtkKdTree> kdTree = vtkSmartPointer<vtkKdTree>::New();
    kdTree->OmitZPartitioning();
    kdTree->BuildLocatorFromPoints(pts);

    vtkSmartPointer<vtkPolyData> linesA = vtkSmartPointer<vtkPolyData>::New();
    linesA->SetPoints(pts);
    linesA->Allocate(1);

    IndexedPoly::const_iterator itrA, itrB;

    for (const auto &ids : indexedPolys) {
        for (itrA = ids.begin(); itrA != ids.end(); ++itrA) {
            itrB = itrA+1;
            if (itrB == ids.end()) {
                itrB = ids.begin();
            }

            vtkIdList *line = vtkIdList::New();
            line->InsertNextId(*itrA);
            line->InsertNextId(*itrB);

            linesA->InsertNextCell(VTK_LINE, line);

            line->Delete();
        }
    }

    //EED 2023-07-24
//    WriteVTK("linesA.vtk", linesA);

    vtkSmartPointer<vtkModifiedBSPTree> bspTreeA = vtkSmartPointer<vtkModifiedBSPTree>::New();
    bspTreeA->SetDataSet(linesA);

    int n = 0;

    PolyConnsType polyConns;

    FindConns(linesA, kdTree, bspTreeA, polyConns, indexedPolys, sources, n);

    PolyConnsType connected {{0, {}}};
    std::set<vtkIdType> restricted; // keine der conns darf im gleichen punkt beginnen

    vtkSmartPointer<vtkPolyData> linesB = vtkSmartPointer<vtkPolyData>::New();
    linesB->SetPoints(pts);
    linesB->Allocate(1);

    vtkSmartPointer<vtkModifiedBSPTree> bspTreeB = vtkSmartPointer<vtkModifiedBSPTree>::New();
    bspTreeB->SetDataSet(linesB);

    ConnsType firstConns;

    std::size_t i, numPolys = indexedPolys.size();

    double ptA[3], ptB[3];

    while (connected.size() < numPolys) {

        bool foundOne = false;

        for (i = 1; i < numPolys; i++) {
            if (connected.count(i) == 0) {
                const ConnsType &conns = polyConns[i];

                for (auto &conn : conns) {
                    if (connected.count(sources.at(conn.j)) == 1
                        && restricted.count(conn.j) == 0) {

                        pts->GetPoint(conn.i, ptA);
                        pts->GetPoint(conn.j, ptB);

                        if (bspTreeB->IntersectWithLine(ptA, ptB, 1e-5, nullptr, nullptr) == 0) {
                            connected[sources.at(conn.i)].push_back(conn);

                            // das andere poly auch aktualisieren
                            connected[sources.at(conn.j)].emplace_back(conn.d, conn.j, conn.i);

                            restricted.insert(conn.i);
                            restricted.insert(conn.j);

                            vtkIdList *line = vtkIdList::New();
                            line->InsertNextId(conn.i);
                            line->InsertNextId(conn.j);

                            linesB->InsertNextCell(VTK_LINE, line);

                            line->Delete();

                            bspTreeB->Modified();

                            foundOne = true;

                            firstConns.push_back(conn);

                            break;
                        }

                    }
                }
            }
        }

        if (!foundOne) {
            if (!FindConns(linesA, kdTree, bspTreeA, polyConns, indexedPolys, sources, n)) {
                throw std::runtime_error("Merging failed.");
            }
        }
    }

    std::map<std::size_t, std::vector<std::size_t>> chains;

    PolyConnsType::const_iterator itrC;

    for (itrC = connected.begin(); itrC != connected.end(); ++itrC) {
        auto &chain = chains[itrC->first];
        chain.push_back(itrC->first);

        while (chain.back() != 0) {
            chain.push_back(sources.at(connected.at(chain.back()).front().j));
        }
    }

    std::cout << connected;

    decltype(chains)::const_iterator itrD;

    for (itrD = chains.begin(); itrD != chains.end(); ++itrD) {
        std::cout << itrD->first << ": [";
        for (auto &id : itrD->second) {
            std::cout << id << ", ";
        }
        std::cout << "]" << std::endl;
    }

    std::set<std::size_t> solved {0};

    std::deque<std::size_t> searchInds;

    for (i = 1; i < numPolys; i++) {
        if (connected.at(i).size() == 1) {
            searchInds.push_back(i);
        }
    }

    while (!searchInds.empty()) {
        PriosType prios;

        for (auto ind : searchInds) {
            PolyPriosType polyPrios;

            std::cout << "ind " << ind << std::endl;

            const Conn &first = connected.at(ind).back();

            for (auto &conn : polyConns.at(ind)) {
                auto &src = sources.at(conn.j);

                if (polyPrios.count(src) == 1) {
                    continue;
                }

                if (conn.i != first.i
                    && conn.j != first.j
                    && restricted.count(conn.i) == 0
                    && restricted.count(conn.j) == 0) {

                    pts->GetPoint(conn.i, ptA);
                    pts->GetPoint(conn.j, ptB);

                    if (bspTreeB->IntersectWithLine(ptA, ptB, 1e-5, nullptr, nullptr) == 0) {
                        auto &chainA = chains.at(ind),
                            &chainB = chains.at(src);

                        std::set<std::size_t> _chainA(chainA.begin(), chainA.end()),
                            _chainB(chainB.begin(), chainB.end());

                        // gemeinsame eltern
                        std::set<std::size_t> shared;

                        std::set_intersection(_chainA.begin(), _chainA.end(), _chainB.begin(), _chainB.end(), std::inserter(shared, shared.end()));

                        // gemeinsame eltern müssen sich alle in solved befinden
                        if (std::includes(solved.begin(), solved.end(), shared.begin(), shared.end())) {
                            std::set<std::size_t> solvable;

                            std::set_difference(_chainA.begin(), _chainA.end(), solved.begin(), solved.end(), std::inserter(solvable, solvable.end()));
                            std::set_difference(_chainB.begin(), _chainB.end(), solved.begin(), solved.end(), std::inserter(solvable, solvable.end()));

                            polyPrios.emplace(std::piecewise_construct,
                                std::forward_as_tuple(src),
                                std::forward_as_tuple(conn, solvable, -conn.d));
                        }
                    }
                }
            }

            PolyPriosType::const_iterator itr;
            for (itr = polyPrios.begin(); itr != polyPrios.end(); ++itr) {
                prios.insert(itr->second);
            }
        }

        if (!prios.empty()) {
            auto &prio = *prios.rbegin();

            std::cout << "found " << prio << std::endl;

            auto &conns = connected.at(sources.at(prio.conn.i));

            conns.push_back(prio.conn);

            connected.at(sources.at(prio.conn.j)).emplace_back(prio.conn.d, prio.conn.j, prio.conn.i);

            restricted.insert(prio.conn.i);
            restricted.insert(prio.conn.j);

            vtkIdList *line = vtkIdList::New();
            line->InsertNextId(prio.conn.i);
            line->InsertNextId(prio.conn.j);

            linesB->InsertNextCell(VTK_LINE, line);

            line->Delete();

            bspTreeB->Modified();

            solved.insert(prio.solvable.begin(), prio.solvable.end());

            searchInds.erase(std::find(searchInds.begin(), searchInds.end(), sources.at(prio.conn.i)));

            auto itr = std::find(searchInds.begin(), searchInds.end(), sources.at(prio.conn.j));

            if (itr != searchInds.end()) {
                searchInds.erase(itr);
            }
        } else {
            if (!FindConns(linesA, kdTree, bspTreeA, polyConns, indexedPolys, sources, n)) {
                throw std::runtime_error("Merging failed.");
            }
        }
    }

    std::cout << connected;

//EED 2023-07-24
//    WriteVTK("linesB.vtk", linesB);

    // stage 1

    struct Cmp {
        bool operator() (const Conn &a, const Conn &b) const {
            return std::tie(a.i, a.j) < std::tie(b.i, b.j);
        }
    };

    std::set<Conn, Cmp> usedConns;

    IndexedPoly polyA {indexedPolys.front()};

    for (const auto &first : firstConns) {
        auto itrA = std::find(polyA.begin(), polyA.end(), first.j);

        assert(itrA != polyA.end());

        auto &polyB = indexedPolys.at(sources.at(first.i));

        auto itrB = std::find(polyB.begin(), polyB.end(), first.i);

        assert(itrB != polyB.end());

        std::rotate(polyA.begin(), itrA, polyA.end());
        std::rotate(polyB.begin(), itrB, polyB.end());

        IndexedPoly newPoly {polyA};
        newPoly.push_back(polyA.front());
        newPoly.push_back(polyB.front());

        newPoly.insert(newPoly.end(), polyB.rbegin(), polyB.rend());

        polyA.swap(newPoly);

        usedConns.insert(first);

    }

    PolysType newPolysA;
    GetPolys(refPts, {polyA}, newPolysA);

    //EED 2023-07-24
//    WritePolys("merged_stage1.vtk", newPolysA);

    // stage 2

    std::set<Conn, Cmp> leftConns;

    for (itrC = connected.begin(); itrC != connected.end(); ++itrC) {
        if (itrC->first == 0) {
            continue;
        }

        auto &conns = itrC->second;

        ConnsType::const_iterator itr;

        for (itr = conns.begin()+1; itr != conns.end(); ++itr) {
            Conn conn(0, itr->j, itr->i);

            if (usedConns.find(conn) == usedConns.end()) {
                if (itr->i < itr->j) {
                    leftConns.emplace(0, itr->i, itr->j);
                } else {
                    leftConns.insert(std::move(conn));
                }
            }
        }

    }

    std::cout << "leftConns: [";
    for (auto &conn : leftConns) {
        std::cout << conn << ", ";
    }
    std::cout << "]" << std::endl;

    IndexedPolysType splitted {polyA};

    for (auto &conn : leftConns) {
        IndexedPolysType::iterator itr;

        for (itr = splitted.begin(); itr != splitted.end(); ++itr) {
            auto &poly = *itr;

            auto itrA = std::find(poly.begin(), poly.end(), conn.i);

            if (itrA != poly.end()) {
                std::rotate(poly.begin(), itrA, poly.end());

                auto itrB = std::find(poly.begin(), poly.end(), conn.j);

                IndexedPoly newPolyA(poly.begin(), itrB+1);
                IndexedPoly newPolyB(itrB, poly.end());

                newPolyB.push_back(poly.front());

                splitted.erase(itr);

                splitted.push_back(std::move(newPolyA));
                splitted.push_back(std::move(newPolyB));

                break;
            }
        }
    }

    PolysType newPolysB;
    GetPolys(refPts, splitted, newPolysB);

    //EED 2023-07-24
//    WritePolys("merged_stage2.vtk", newPolysB);

    std::move(newPolysB.begin(), newPolysB.end(), std::back_inserter(merged));

}

bool Merger::FindConns (vtkPolyData *lines, vtkSmartPointer<vtkKdTree> kdTree, vtkSmartPointer<vtkModifiedBSPTree> bspTree, PolyConnsType &polyConns, const IndexedPolysType &indexedPolys, const SourcesType &sources, int &n) {

    vtkPoints *pts = lines->GetPoints();

    if (n > pts->GetNumberOfPoints()) {
        return false;
    }

    n += 10;

    vtkSmartPointer<vtkIdList> foundPts = vtkSmartPointer<vtkIdList>::New();

    vtkIdType i, numPts;

    vtkIdType idB;

    vtkSmartPointer<vtkIdList> lineIds = vtkSmartPointer<vtkIdList>::New();

    double ptA[3], ptB[3];

    bool good;

    vtkIdType j;
    vtkIdType _idA, _idB;

    std::map<std::size_t, std::set<Conn, ConnCmp>> _polyConns;

    vtkSmartPointer<vtkIdList> line = vtkSmartPointer<vtkIdList>::New();

    for (const auto &ids : indexedPolys) {
        for (vtkIdType idA : ids) {
            pts->GetPoint(idA, ptA);

            kdTree->FindClosestNPoints(n, ptA, foundPts);

            numPts = foundPts->GetNumberOfIds();

            for (i = 0; i < numPts; i++) {
                idB = foundPts->GetId(i);

                auto srcA = sources.at(idA),
                    srcB = sources.at(idB);

                if (srcA == srcB) {
                    continue;
                }

                pts->GetPoint(idB, ptB);

                good = true;

                if (bspTree->IntersectWithLine(ptA, ptB, 1e-5, nullptr, lineIds) == 1) {
                    for (j = 0; j < lineIds->GetNumberOfIds(); j++) {
                        lines->GetCellPoints(lineIds->GetId(j), line);

                        _idA = line->GetId(0);
                        _idB = line->GetId(1);

                        if (_idA != idA && _idA != idB
                            && _idB != idA && _idB != idB) {

                            good = false;
                            break;
                        }
                    }
                }

                if (good) {
                    double d = vtkMath::Distance2BetweenPoints(ptA, ptB);

                    _polyConns[srcA].emplace(d, idA, idB);
                    _polyConns[srcB].emplace(d, idB, idA);
                }
            }
        }
    }

    decltype(_polyConns)::const_iterator itr;

    for (itr = _polyConns.begin(); itr != _polyConns.end(); ++itr) {
        auto &_conns = itr->second;

        ConnsType conns(_conns.begin(), _conns.end());
        std::sort(conns.begin(), conns.end());

        polyConns[itr->first].swap(conns);

    }

    return true;
}