netgen/libsrc/occ/occgenmesh.cpp

#ifdef OCCGEOMETRY

#include <mystdlib.h>
#include <occgeom.hpp>
#include <meshing.hpp>


namespace netgen
{

#include "occmeshsurf.hpp"

#define TCL_OK 0
#define TCL_ERROR 1

#define DIVIDEEDGESECTIONS 1000
#define IGNORECURVELENGTH 1e-4
#define VSMALL 1e-10


  DLL_HEADER bool merge_solids = 1;


  // can you please explain what you intend to compute here (JS) !!!
  double Line :: Dist (Line l)
  {
    Vec<3> n = p1-p0;
    Vec<3> q = l.p1-l.p0;
    double nq = n*q;

    Point<3> p = p0 + 0.5*n;
    double lambda = (p-l.p0)*n / (nq + VSMALL);

    if (lambda >= 0 && lambda <= 1)
      {
        double d = (p-l.p0-lambda*q).Length();
        //        if (d < 1e-3) d = 1e99;
        return d;
      }
    else
      return 1e99;
  }

  inline Point<3> occ2ng (const gp_Pnt & p)
  {
    return Point<3> (p.X(), p.Y(), p.Z());
  }

  double ComputeH (double kappa, const MeshingParameters & mparam)
  {
    kappa *= mparam.curvaturesafety;
    /*
    double hret;

    if (mparam.maxh * kappa < 1)
      hret = mparam.maxh;
    else
      hret = 1 / (kappa + VSMALL);

    if (mparam.maxh < hret)
      hret = mparam.maxh;

    return hret;
    */
    // return min(mparam.maxh, 1/kappa);
    return (mparam.maxh*kappa < 1) ? mparam.maxh : 1/kappa;
  }



  void RestrictHTriangle (gp_Pnt2d & par0, gp_Pnt2d & par1, gp_Pnt2d & par2,
                          BRepLProp_SLProps * prop, BRepLProp_SLProps * prop2, Mesh & mesh, int depth, double h,
                          const MeshingParameters & mparam)
  {
    int ls = -1;

    gp_Pnt pnt0,pnt1,pnt2;

    prop->SetParameters (par0.X(), par0.Y());
    pnt0 = prop->Value();

    prop->SetParameters (par1.X(), par1.Y());
    pnt1 = prop->Value();

    prop->SetParameters (par2.X(), par2.Y());
    pnt2 = prop->Value();

    double aux;
    double maxside = pnt0.Distance(pnt1);
    ls = 2;
    aux = pnt1.Distance(pnt2);
    if(aux > maxside)
      {
        maxside = aux;
        ls = 0;
      }
    aux = pnt2.Distance(pnt0);
    if(aux > maxside)
      {
        maxside = aux;
        ls = 1;
      }



    gp_Pnt2d parmid;

    parmid.SetX( (par0.X()+par1.X()+par2.X()) / 3 );
    parmid.SetY( (par0.Y()+par1.Y()+par2.Y()) / 3 );

    if (depth%3 == 0)
      {
        double curvature = 0;

        prop2->SetParameters (parmid.X(), parmid.Y());
        if (!prop2->IsCurvatureDefined())
          {
            (*testout) << "curvature not defined!" << endl;
            return;
          }
        curvature = max(fabs(prop2->MinCurvature()),
                        fabs(prop2->MaxCurvature()));

        prop2->SetParameters (par0.X(), par0.Y());
        if (!prop2->IsCurvatureDefined())
          {
            (*testout) << "curvature not defined!" << endl;
            return;
          }
        curvature = max(curvature,max(fabs(prop2->MinCurvature()),
                                      fabs(prop2->MaxCurvature())));

        prop2->SetParameters (par1.X(), par1.Y());
        if (!prop2->IsCurvatureDefined())
          {
            (*testout) << "curvature not defined!" << endl;
            return;
          }
        curvature = max(curvature,max(fabs(prop2->MinCurvature()),
                                      fabs(prop2->MaxCurvature())));

        prop2->SetParameters (par2.X(), par2.Y());
        if (!prop2->IsCurvatureDefined())
          {
            (*testout) << "curvature not defined!" << endl;
            return;
          }
        curvature = max(curvature,max(fabs(prop2->MinCurvature()),
                                      fabs(prop2->MaxCurvature())));

        //(*testout) << "curvature " << curvature << endl;

        if (curvature < 1e-3)
          {
            //(*testout) << "curvature too small (" << curvature << ")!" << endl;
            return;
            // return war bis 10.2.05 auskommentiert
          }



        h = ComputeH (curvature+1e-10, mparam);

        if(h < 1e-4*maxside)
          return;


        // if (h > 30) return;
      }

    if (h < maxside && depth < 10)
      {
        //cout << "\r h " << h << flush;
        gp_Pnt2d pm;

        //cout << "h " << h << " maxside " << maxside << " depth " << depth << endl;
        //cout << "par0 " << par0.X() << " " << par0.Y()
        //<< " par1 " << par1.X() << " " << par1.Y()
        //   << " par2 " << par2.X() << " " << par2.Y()<< endl;

        if(ls == 0)
          {
            pm.SetX(0.5*(par1.X()+par2.X())); pm.SetY(0.5*(par1.Y()+par2.Y()));
            RestrictHTriangle(pm, par2, par0, prop, prop2, mesh, depth+1, h, mparam);
            RestrictHTriangle(pm, par0, par1, prop, prop2, mesh, depth+1, h, mparam);
          }
        else if(ls == 1)
          {
            pm.SetX(0.5*(par0.X()+par2.X())); pm.SetY(0.5*(par0.Y()+par2.Y()));
            RestrictHTriangle(pm, par1, par2, prop, prop2, mesh, depth+1, h, mparam);
            RestrictHTriangle(pm, par0, par1, prop, prop2, mesh, depth+1, h, mparam);
          }
        else if(ls == 2)
          {
            pm.SetX(0.5*(par0.X()+par1.X())); pm.SetY(0.5*(par0.Y()+par1.Y()));
            RestrictHTriangle(pm, par1, par2, prop, prop2, mesh, depth+1, h, mparam);
            RestrictHTriangle(pm, par2, par0, prop, prop2, mesh, depth+1, h, mparam);
          }

      }
    else
      {
        gp_Pnt pnt;
        Point3d p3d;

        prop->SetParameters (parmid.X(), parmid.Y());
        pnt = prop->Value();
        p3d = Point3d(pnt.X(), pnt.Y(), pnt.Z());
        mesh.RestrictLocalH (p3d, h);

        p3d = Point3d(pnt0.X(), pnt0.Y(), pnt0.Z());
        mesh.RestrictLocalH (p3d, h);

        p3d = Point3d(pnt1.X(), pnt1.Y(), pnt1.Z());
        mesh.RestrictLocalH (p3d, h);

        p3d = Point3d(pnt2.X(), pnt2.Y(), pnt2.Z());
        mesh.RestrictLocalH (p3d, h);

        //(*testout) << "p = " << p3d << ", h = " << h << ", maxside = " << maxside << endl;

      }
  }



  void DivideEdge (TopoDS_Edge & edge, NgArray<MeshPoint> & ps,
                   NgArray<double> & params, Mesh & mesh,
                   const MeshingParameters & mparam)
  {
    double s0, s1;
    double maxh = mparam.maxh;
    int nsubedges = 1;
    gp_Pnt pnt, oldpnt;
    double svalue[DIVIDEEDGESECTIONS];

    GProp_GProps system;
    BRepGProp::LinearProperties(edge, system);
    double L = system.Mass();

    Handle(Geom_Curve) c = BRep_Tool::Curve(edge, s0, s1);

    double hvalue[DIVIDEEDGESECTIONS+1];
    hvalue[0] = 0;
    pnt = c->Value(s0);

    double olddist = 0;
    double dist = 0;

    int tmpVal = (int)(DIVIDEEDGESECTIONS);

    for (int i = 1; i <= tmpVal; i++)
      {
        oldpnt = pnt;
        pnt = c->Value(s0+(i/double(DIVIDEEDGESECTIONS))*(s1-s0));
        hvalue[i] = hvalue[i-1] +
          1.0/mesh.GetH(Point3d(pnt.X(), pnt.Y(), pnt.Z()))*
          pnt.Distance(oldpnt);

        //(*testout) << "mesh.GetH(Point3d(pnt.X(), pnt.Y(), pnt.Z())) " << mesh.GetH(Point3d(pnt.X(), pnt.Y(), pnt.Z()))
        //	   <<  " pnt.Distance(oldpnt) " << pnt.Distance(oldpnt) << endl;

        olddist = dist;
        dist = pnt.Distance(oldpnt);
      }

    //  nsubedges = int(ceil(hvalue[DIVIDEEDGESECTIONS]));
    nsubedges = max (1, int(floor(hvalue[DIVIDEEDGESECTIONS]+0.5)));

    ps.SetSize(nsubedges-1);
    params.SetSize(nsubedges+1);

    int i = 1;
    int i1 = 0;
    do
      {
        if (hvalue[i1]/hvalue[DIVIDEEDGESECTIONS]*nsubedges >= i)
          {
            params[i] = s0+(i1/double(DIVIDEEDGESECTIONS))*(s1-s0);
            pnt = c->Value(params[i]);
            ps[i-1] = MeshPoint (Point3d(pnt.X(), pnt.Y(), pnt.Z()));
            i++;
          }
        i1++;
        if (i1 > DIVIDEEDGESECTIONS)
          {
            nsubedges = i;
            ps.SetSize(nsubedges-1);
            params.SetSize(nsubedges+1);
            cout << "divide edge: local h too small" << endl;
          }
      } while (i < nsubedges);

    params[0] = s0;
    params[nsubedges] = s1;

    if (params[nsubedges] <= params[nsubedges-1])
      {
        cout << "CORRECTED" << endl;
        ps.SetSize (nsubedges-2);
        params.SetSize (nsubedges);
        params[nsubedges] = s1;
      }
  }




  void OCCFindEdges (const OCCGeometry & geom, Mesh & mesh, const MeshingParameters & mparam)
  {
    static Timer t("OCCFindEdges"); RegionTimer r(t);
    static Timer tsearch("OCCFindEdges - search point");
    const char * savetask = multithread.task;
    multithread.task = "Edge meshing";

    (*testout) << "edge meshing" << endl;

    int nvertices = geom.vmap.Extent();
    int nedges = geom.emap.Extent();

    (*testout) << "nvertices = " << nvertices << endl;
    (*testout) << "nedges = " << nedges << endl;

    double eps = 1e-6 * geom.GetBoundingBox().Diam();

    tsearch.Start();
    for (int i = 1; i <= nvertices; i++)
      {
        gp_Pnt pnt = BRep_Tool::Pnt (TopoDS::Vertex(geom.vmap(i)));
        MeshPoint mp( Point<3>(pnt.X(), pnt.Y(), pnt.Z()) );

        bool exists = 0;
        if (merge_solids)
          for (PointIndex pi : mesh.Points().Range())
            if (Dist2 (mesh[pi], Point<3>(mp)) < eps*eps)
              {
                exists = true;
                break;
              }

        if (!exists)
          mesh.AddPoint (mp);
      }
    tsearch.Stop();
    
    (*testout) << "different vertices = " << mesh.GetNP() << endl;

    // int first_ep = mesh.GetNP()+1;
    // PointIndex first_ep = mesh.Points().End();
    PointIndex first_ep = *mesh.Points().Range().end();
    auto vertexrange = mesh.Points().Range();

    NgArray<int> face2solid[2];
    for (int i = 0; i < 2; i++)
      {
        face2solid[i].SetSize (geom.fmap.Extent());
        face2solid[i] = 0;
      }

    int solidnr = 0;
    for (TopExp_Explorer exp0(geom.shape, TopAbs_SOLID); exp0.More(); exp0.Next())
      {
        solidnr++;
        for (TopExp_Explorer exp1(exp0.Current(), TopAbs_FACE); exp1.More(); exp1.Next())
          {
            TopoDS_Face face = TopoDS::Face(exp1.Current());
            int facenr = geom.fmap.FindIndex(face);

            if (face2solid[0][facenr-1] == 0)
              face2solid[0][facenr-1] = solidnr;
            else
              face2solid[1][facenr-1] = solidnr;
          }
      }


    int total = 0;
    for (int i3 = 1; i3 <= geom.fmap.Extent(); i3++)
      for (TopExp_Explorer exp2(geom.fmap(i3), TopAbs_WIRE); exp2.More(); exp2.Next())
        for (TopExp_Explorer exp3(exp2.Current(), TopAbs_EDGE); exp3.More(); exp3.Next())
          total++;


    int facenr = 0;
    int edgenr = 0;


    (*testout) << "faces = " << geom.fmap.Extent() << endl;
    int curr = 0;

    for (int i3 = 1; i3 <= geom.fmap.Extent(); i3++)
      {
        TopoDS_Face face = TopoDS::Face(geom.fmap(i3));
        facenr = geom.fmap.FindIndex (face);       // sollte doch immer == i3 sein ??? JS

        int solidnr0 = face2solid[0][i3-1];
        int solidnr1 = face2solid[1][i3-1];

        /* auskommentiert am 3.3.05 von robert
           for (exp2.Init (geom.somap(solidnr0), TopAbs_FACE); exp2.More(); exp2.Next())
           {
           TopoDS_Face face2 = TopoDS::Face(exp2.Current());
           if (geom.fmap.FindIndex(face2) == facenr)
           {
           //		      if (face.Orientation() != face2.Orientation()) swap (solidnr0, solidnr1);
           }
           }
        */

        mesh.AddFaceDescriptor (FaceDescriptor(facenr, solidnr0, solidnr1, 0));

        // Philippose - 06/07/2009
        // Add the face colour to the mesh data
        Quantity_Color face_colour;

        if(!(geom.face_colours.IsNull())
           && (geom.face_colours->GetColor(face,XCAFDoc_ColorSurf,face_colour)))
          {
            mesh.GetFaceDescriptor(facenr).SetSurfColour({face_colour.Red(),face_colour.Green(),face_colour.Blue()});
          }
        else
          {
            mesh.GetFaceDescriptor(facenr).SetSurfColour({0.0,1.0,0.0});
          }

        if(geom.fnames.Size()>=facenr) 
          mesh.GetFaceDescriptor(facenr).SetBCName(&geom.fnames[facenr-1]);
        mesh.GetFaceDescriptor(facenr).SetBCProperty(facenr);
        // ACHTUNG! STIMMT NICHT ALLGEMEIN (RG)


        Handle(Geom_Surface) occface = BRep_Tool::Surface(face);

        for (TopExp_Explorer exp2 (face, TopAbs_WIRE); exp2.More(); exp2.Next())
          {
            TopoDS_Shape wire = exp2.Current();

            for (TopExp_Explorer exp3 (wire, TopAbs_EDGE); exp3.More(); exp3.Next())
              {
                curr++;
                (*testout) << "edge nr " << curr << endl;
                multithread.percent = 100 * curr / double (total);
                if (multithread.terminate) return;

                TopoDS_Edge edge = TopoDS::Edge (exp3.Current());
                if (BRep_Tool::Degenerated(edge))
                  {
                    //(*testout) << "ignoring degenerated edge" << endl;
                    continue;
                  }

                if (geom.vmap.FindIndex(TopExp::FirstVertex (edge)) ==
                    geom.vmap.FindIndex(TopExp::LastVertex (edge)))
                  {
                    GProp_GProps system;
                    BRepGProp::LinearProperties(edge, system);

                    if (system.Mass() < eps)
                      {
                        cout << "ignoring edge " << geom.emap.FindIndex (edge)
                             << ". closed edge with length < " << eps << endl;
                        continue;
                      }
                  }


                Handle(Geom2d_Curve) cof;
                double s0, s1;
                cof = BRep_Tool::CurveOnSurface (edge, face, s0, s1);

                int geomedgenr = geom.emap.FindIndex(edge);

                NgArray <MeshPoint> mp;
                NgArray <double> params;

                DivideEdge (edge, mp, params, mesh, mparam);

                NgArray<PointIndex> pnums(mp.Size()+2);

                if (!merge_solids)
                  {
                    pnums[0] = geom.vmap.FindIndex (TopExp::FirstVertex (edge)) + PointIndex::BASE-1;
                    pnums.Last() = geom.vmap.FindIndex (TopExp::LastVertex (edge)) + PointIndex::BASE-1;
                  }
                else
                  {
                    Point<3> fp = occ2ng (BRep_Tool::Pnt (TopExp::FirstVertex (edge)));
                    Point<3> lp = occ2ng (BRep_Tool::Pnt (TopExp::LastVertex (edge)));

                    pnums[0] = PointIndex::INVALID;
                    pnums.Last() = PointIndex::INVALID;
                    for (PointIndex pi : vertexrange)
                      {
                        if (Dist2 (mesh[pi], fp) < eps*eps) pnums[0] = pi;
                        if (Dist2 (mesh[pi], lp) < eps*eps) pnums.Last() = pi;
                      }
                  }

                for (size_t i = 1; i <= mp.Size(); i++)
                  {
                    bool exists = 0;
                    tsearch.Start();

                    // for (PointIndex j = first_ep; j < mesh.Points().End(); j++)
                    for (PointIndex j = first_ep; j < *mesh.Points().Range().end(); j++)
                      if ((mesh.Point(j)-Point<3>(mp[i-1])).Length() < eps)
                        {
                          exists = true;
                          pnums[i] = j;
                          break;
                        }
                      
                    tsearch.Stop();
                    
                    if (!exists)
                      pnums[i] = mesh.AddPoint (mp[i-1]);
                  }
                (*testout) << "NP = " << mesh.GetNP() << endl;
                //(*testout) << pnums[pnums.Size()-1] << endl;

                for (size_t i = 1; i <= mp.Size()+1; i++)
                  {
                    edgenr++;
                    Segment seg;

                    seg[0] = pnums[i-1];
                    seg[1] = pnums[i];
                    seg.edgenr = edgenr;
                    seg.si = facenr;
                    seg.epgeominfo[0].dist = params[i-1];
                    seg.epgeominfo[1].dist = params[i];
                    seg.epgeominfo[0].edgenr = geomedgenr;
                    seg.epgeominfo[1].edgenr = geomedgenr;

                    gp_Pnt2d p2d;
                    p2d = cof->Value(params[i-1]);
                    //			if (i == 1) p2d = cof->Value(s0);
                    seg.epgeominfo[0].u = p2d.X();
                    seg.epgeominfo[0].v = p2d.Y();
                    p2d = cof->Value(params[i]);
                    //			if (i == mp.Size()+1) p2d = cof -> Value(s1);
                    seg.epgeominfo[1].u = p2d.X();
                    seg.epgeominfo[1].v = p2d.Y();

                    /*
                      if (occface->IsUPeriodic())
                      {
                      cout << "U Periodic" << endl;
                      if (fabs(seg.epgeominfo[1].u-seg.epgeominfo[0].u) >
                      fabs(seg.epgeominfo[1].u-
                      (seg.epgeominfo[0].u-occface->UPeriod())))
                      seg.epgeominfo[0].u = p2d.X()+occface->UPeriod();

                      if (fabs(seg.epgeominfo[1].u-seg.epgeominfo[0].u) >
                      fabs(seg.epgeominfo[1].u-
                      (seg.epgeominfo[0].u+occface->UPeriod())))
                      seg.epgeominfo[0].u = p2d.X()-occface->UPeriod();
                      }

                      if (occface->IsVPeriodic())
                      {
                      cout << "V Periodic" << endl;
                      if (fabs(seg.epgeominfo[1].v-seg.epgeominfo[0].v) >
                      fabs(seg.epgeominfo[1].v-
                      (seg.epgeominfo[0].v-occface->VPeriod())))
                      seg.epgeominfo[0].v = p2d.Y()+occface->VPeriod();

                      if (fabs(seg.epgeominfo[1].v-seg.epgeominfo[0].v) >
                      fabs(seg.epgeominfo[1].v-
                      (seg.epgeominfo[0].v+occface->VPeriod())))
                      seg.epgeominfo[0].v = p2d.Y()-occface->VPeriod();
                      }
                    */

                    if (edge.Orientation() == TopAbs_REVERSED)
                      {
                        swap (seg[0], seg[1]);
                        swap (seg.epgeominfo[0].dist, seg.epgeominfo[1].dist);
                        swap (seg.epgeominfo[0].u, seg.epgeominfo[1].u);
                        swap (seg.epgeominfo[0].v, seg.epgeominfo[1].v);
                      }

                    mesh.AddSegment (seg);

                    //edgesegments[geomedgenr-1]->Append(mesh.GetNSeg());

                  }
              }
          }
      }

    //	for(i=1; i<=mesh.GetNSeg(); i++)
    //		(*testout) << "edge " << mesh.LineSegment(i).edgenr << " face " << mesh.LineSegment(i).si
    //				<< " p1 " << mesh.LineSegment(i)[0] << " p2 " << mesh.LineSegment(i)[1] << endl;
    //	exit(10);

    mesh.CalcSurfacesOfNode();
    multithread.task = savetask;
  }




  void OCCMeshSurface (const OCCGeometry & geom, Mesh & mesh,
                       const MeshingParameters & mparam)
  {
    static Timer t("OCCMeshSurface"); RegionTimer r(t);
    
    // int i, j, k;
    // int changed;

    const char * savetask = multithread.task;
    multithread.task = "Surface meshing";

    geom.facemeshstatus = 0;

    int noldp = mesh.GetNP();

    double starttime = GetTime();

    NgArray<int, PointIndex::BASE> glob2loc(noldp);

    //int projecttype = PARAMETERSPACE;

    int projecttype = PARAMETERSPACE;

    int notrys = 1;

    int surfmesherror = 0;

    for (int k = 1; k <= mesh.GetNFD(); k++)
      {
        if(1==0 && !geom.fvispar[k-1].IsDrawable())
          {
            (*testout) << "ignoring face " << k << endl;
            cout << "ignoring face " << k << endl;
            continue;
          }

        (*testout) << "mesh face " << k << endl;
        multithread.percent = 100 * k / (mesh.GetNFD() + VSMALL);
        geom.facemeshstatus[k-1] = -1;

        FaceDescriptor & fd = mesh.GetFaceDescriptor(k);

        int oldnf = mesh.GetNSE();

        Box<3> bb = geom.GetBoundingBox();

        int projecttype = PLANESPACE;
        
        static Timer tinit("init");
        tinit.Start();
        Meshing2OCCSurfaces meshing(geom, TopoDS::Face(geom.fmap(k)), bb, projecttype, mparam);
        tinit.Stop();


        static Timer tprint("print");
        tprint.Start();
        if (meshing.GetProjectionType() == PLANESPACE)
          PrintMessage (2, "Face ", k, " / ", mesh.GetNFD(), " (plane space projection)");
        else
          PrintMessage (2, "Face ", k, " / ", mesh.GetNFD(), " (parameter space projection)");
        tprint.Stop();
        if (surfmesherror)
          cout << "Surface meshing error occurred before (in " << surfmesherror << " faces)" << endl;

        //      Meshing2OCCSurfaces meshing(f2, bb);
        meshing.SetStartTime (starttime);
        //(*testout) << "Face " << k << endl << endl;


        if (meshing.GetProjectionType() == PLANESPACE)
          {
            static Timer t("MeshSurface: Find edges and points - Physical"); RegionTimer r(t);
            int cntp = 0;
            glob2loc = 0;

            for (Segment & seg : mesh.LineSegments())
              if (seg.si == k)
                for (int j = 0; j < 2; j++)
                  {
                    PointIndex pi = seg[j];
                    if (glob2loc[pi] == 0)
                      {
                        meshing.AddPoint (mesh.Point(pi), pi);
                        cntp++;
                        glob2loc[pi] = cntp;
                      }
                  }

            /*
            for (int i = 1; i <= mesh.GetNSeg(); i++)
              {
                Segment & seg = mesh.LineSegment(i);
            */
            for (Segment & seg : mesh.LineSegments())                
              if (seg.si == k)
                {
                  PointGeomInfo gi0, gi1;
                  gi0.trignum = gi1.trignum = k;
                  gi0.u = seg.epgeominfo[0].u;
                  gi0.v = seg.epgeominfo[0].v;
                  gi1.u = seg.epgeominfo[1].u;
                  gi1.v = seg.epgeominfo[1].v;
                  
                  meshing.AddBoundaryElement (glob2loc[seg[0]], glob2loc[seg[1]], gi0, gi1);
                }
          }
        else
          {
            static Timer t("MeshSurface: Find edges and points - Parameter"); RegionTimer r(t);
            
            int cntp = 0;

            /*
            for (int i = 1; i <= mesh.GetNSeg(); i++)
              if (mesh.LineSegment(i).si == k)
                cntp+=2;
            */
            for (Segment & seg : mesh.LineSegments())
              if (seg.si == k)
                cntp += 2;

            NgArray<PointGeomInfo> gis;

            gis.SetAllocSize (cntp);
            gis.SetSize (0);

            for (int i = 1; i <= mesh.GetNSeg(); i++)
              {
                Segment & seg = mesh.LineSegment(i);
                if (seg.si == k)
                  {
                    PointGeomInfo gi0, gi1;
                    gi0.trignum = gi1.trignum = k;
                    gi0.u = seg.epgeominfo[0].u;
                    gi0.v = seg.epgeominfo[0].v;
                    gi1.u = seg.epgeominfo[1].u;
                    gi1.v = seg.epgeominfo[1].v;

                    int locpnum[2] = {0, 0};

                    for (int j = 0; j < 2; j++)
                      {
                        PointGeomInfo gi = (j == 0) ? gi0 : gi1;

                        /*
                        int l;
                        for (l = 0; l < gis.Size() && locpnum[j] == 0; l++)
                          {
                            double dist = sqr (gis[l].u-gi.u)+sqr(gis[l].v-gi.v);

                            if (dist < 1e-10)
                              locpnum[j] = l+1;
                          }

                        if (locpnum[j] == 0)
                          {
                            PointIndex pi = seg[j];
                            meshing.AddPoint (mesh.Point(pi), pi);

                            gis.SetSize (gis.Size()+1);
                            gis[l] = gi;
                            locpnum[j] = l+1;
                          }
                        */
                        for (int l = 0; l < gis.Size(); l++)
                          {
                            double dist = sqr (gis[l].u-gi.u)+sqr(gis[l].v-gi.v);
                            if (dist < 1e-10)
                              {
                                locpnum[j] = l+1;
                                break;
                              }
                          }

                        if (locpnum[j] == 0)
                          {
                            PointIndex pi = seg[j];
                            meshing.AddPoint (mesh.Point(pi), pi);

                            gis.Append (gi);
                            locpnum[j] = gis.Size();
                          }
                      }

                    meshing.AddBoundaryElement (locpnum[0], locpnum[1], gi0, gi1);
                  }
              }
          }




        // Philippose - 15/01/2009
        double maxh = geom.face_maxh[k-1];
        //double maxh = mparam.maxh;
        //      int noldpoints = mesh->GetNP();
        int noldsurfel = mesh.GetNSE();

        static Timer tsurfprop("surfprop");
        tsurfprop.Start();
        GProp_GProps sprops;
        BRepGProp::SurfaceProperties(TopoDS::Face(geom.fmap(k)),sprops);
        tsurfprop.Stop();
        meshing.SetMaxArea(2.*sprops.Mass());

        MESHING2_RESULT res;

        // TODO: check overlap not correctly working here
        MeshingParameters mparam_without_overlap = mparam;
        mparam_without_overlap.checkoverlap = false;
        
        try {
          static Timer t("GenerateMesh"); RegionTimer reg(t);
          res = meshing.GenerateMesh (mesh, mparam_without_overlap, maxh, k);
        }

        catch (SingularMatrixException)
          {
            (*myerr) << "Singular Matrix" << endl;
            res = MESHING2_GIVEUP;
          }

        catch (UVBoundsException)
          {
            (*myerr) << "UV bounds exceeded" << endl;
            res = MESHING2_GIVEUP;
          }

        projecttype = PARAMETERSPACE;
        static Timer t1("rest of loop"); RegionTimer reg1(t1);
          
        if (res != MESHING2_OK)
          {
            if (notrys == 1)
              {
                for (SurfaceElementIndex sei = noldsurfel; sei < mesh.GetNSE(); sei++)
                  mesh.Delete(sei);

                mesh.Compress();

                cout << "retry Surface " << k << endl;

                k--;
                projecttype*=-1;
                notrys++;
                continue;
              }
            else
              {
                geom.facemeshstatus[k-1] = -1;
                PrintError ("Problem in Surface mesh generation");
                surfmesherror++;
                //	      throw NgException ("Problem in Surface mesh generation");
              }
          }
        else
          {
            geom.facemeshstatus[k-1] = 1;
          }

        notrys = 1;

        for (SurfaceElementIndex sei = oldnf; sei < mesh.GetNSE(); sei++)
          mesh[sei].SetIndex (k);

        auto n_illegal_trigs = mesh.FindIllegalTrigs();
        PrintMessage (3, n_illegal_trigs, " illegal triangles");
      }

    //      ofstream problemfile("occmesh.rep");

    //      problemfile << "SURFACEMESHING" << endl << endl;

    if (surfmesherror)
      {
        cout << "WARNING! NOT ALL FACES HAVE BEEN MESHED" << endl;
        cout << "SURFACE MESHING ERROR OCCURRED IN " << surfmesherror << " FACES:" << endl;
        for (int i = 1; i <= geom.fmap.Extent(); i++)
          if (geom.facemeshstatus[i-1] == -1)
            {
              cout << "Face " << i << endl;
              //               problemfile << "problem with face " << i << endl;
              //               problemfile << "vertices: " << endl;
              TopExp_Explorer exp0,exp1,exp2;
              for ( exp0.Init(TopoDS::Face (geom.fmap(i)), TopAbs_WIRE); exp0.More(); exp0.Next() )
                {
                  TopoDS_Wire wire = TopoDS::Wire(exp0.Current());
                  for ( exp1.Init(wire,TopAbs_EDGE); exp1.More(); exp1.Next() )
                    {
                      TopoDS_Edge edge = TopoDS::Edge(exp1.Current());
                      for ( exp2.Init(edge,TopAbs_VERTEX); exp2.More(); exp2.Next() )
                        {
                          TopoDS_Vertex vertex = TopoDS::Vertex(exp2.Current());
                          gp_Pnt point = BRep_Tool::Pnt(vertex);
                          //                        problemfile << point.X() << " " << point.Y() << " " << point.Z() << endl;
                        }
                    }
                }
              //               problemfile << endl;

            }
        cout << endl << endl;
        cout << "for more information open IGES/STEP Topology Explorer" << endl;
        //            problemfile.close();
        throw NgException ("Problem in Surface mesh generation");
      }
    else
      {
        //         problemfile << "OK" << endl << endl;
        //         problemfile.close();
      }
    
    for (int i = 0; i < mesh.GetNFD(); i++)
      mesh.SetBCName (i, mesh.GetFaceDescriptor(i+1).GetBCName());
    multithread.task = savetask;
  }

  void OCCOptimizeSurface(OCCGeometry & geom, Mesh & mesh,
                          const MeshingParameters & mparam)
  {
    const char * savetask = multithread.task;
    multithread.task = "Optimizing surface";

    static Timer timer_opt2d("Optimization 2D");
    timer_opt2d.Start();

    for (int k = 1; k <= mesh.GetNFD(); k++)
      {
        //      if (k != 42) continue;
        //      if (k != 36) continue;

        //      (*testout) << "optimize face " << k << endl;
        multithread.percent = 100 * k / (mesh.GetNFD() + VSMALL);

        FaceDescriptor & fd = mesh.GetFaceDescriptor(k);

        PrintMessage (1, "Optimize Surface ", k);
        for (int i = 1; i <= mparam.optsteps2d; i++)
          {
            //	  (*testout) << "optstep " << i << endl;
            if (multithread.terminate) return;

            {
              MeshOptimize2d meshopt(mesh);
              meshopt.SetFaceIndex (k);
              meshopt.SetImproveEdges (0);
              meshopt.SetMetricWeight (mparam.elsizeweight);
              meshopt.SetWriteStatus (0);
              meshopt.EdgeSwapping (i > mparam.optsteps2d/2);
            }

            if (multithread.terminate) return;
            {
              MeshOptimize2d meshopt(mesh);
              meshopt.SetFaceIndex (k);
              meshopt.SetImproveEdges (0);
              meshopt.SetMetricWeight (mparam.elsizeweight);
              meshopt.SetWriteStatus (0);
              meshopt.ImproveMesh (mparam);
            }

            {
              MeshOptimize2d meshopt(mesh);
              meshopt.SetFaceIndex (k);
              meshopt.SetImproveEdges (0);
              meshopt.SetMetricWeight (mparam.elsizeweight);
              meshopt.SetWriteStatus (0);
              meshopt.CombineImprove ();
            }

            if (multithread.terminate) return;
            {
              MeshOptimize2d meshopt(mesh);
              meshopt.SetFaceIndex (k);
              meshopt.SetImproveEdges (0);
              meshopt.SetMetricWeight (mparam.elsizeweight);
              meshopt.SetWriteStatus (0);
              meshopt.ImproveMesh (mparam);
            }
          }

      }


    mesh.CalcSurfacesOfNode();
    mesh.Compress();
    timer_opt2d.Stop();

    multithread.task = savetask;
  }



  void OCCSetLocalMeshSize(const OCCGeometry & geom, Mesh & mesh,
                           const MeshingParameters & mparam, const OCCParameters& occparam)
  {
    static Timer t1("OCCSetLocalMeshSize");
    RegionTimer regt(t1);
    mesh.SetGlobalH (mparam.maxh);
    mesh.SetMinimalH (mparam.minh);

    NgArray<double> maxhdom;
    maxhdom.SetSize (geom.NrSolids());
    maxhdom = mparam.maxh;

    mesh.SetMaxHDomain (maxhdom);

    Box<3> bb = geom.GetBoundingBox();
    bb.Increase (bb.Diam()/10);

    mesh.SetLocalH (bb.PMin(), bb.PMax(), 0.5);

    if (mparam.uselocalh)
      {
        const char * savetask = multithread.task;
        multithread.percent = 0;

        mesh.SetLocalH (bb.PMin(), bb.PMax(), mparam.grading);

        int nedges = geom.emap.Extent();

        double mincurvelength = IGNORECURVELENGTH;
        double maxedgelen = 0;
        double minedgelen = 1e99;

        if(occparam.resthminedgelenenable) 
          {
            mincurvelength = occparam.resthminedgelen;
            if(mincurvelength < IGNORECURVELENGTH) mincurvelength = IGNORECURVELENGTH;
          }

        multithread.task = "Setting local mesh size (elements per edge)";

        // Philippose - 23/01/2009
        // Find all the parent faces of a given edge
        // and limit the mesh size of the edge based on the
        // mesh size limit of the face
        TopTools_IndexedDataMapOfShapeListOfShape edge_face_map;
        edge_face_map.Clear();
        TopExp::MapShapesAndAncestors(geom.shape, TopAbs_EDGE, TopAbs_FACE, edge_face_map);

        // setting elements per edge
        for (int i = 1; i <= nedges && !multithread.terminate; i++)
          {
            TopoDS_Edge e = TopoDS::Edge (geom.emap(i));
            multithread.percent = 100 * (i-1)/double(nedges);
            if (BRep_Tool::Degenerated(e)) continue;

            GProp_GProps system;
            BRepGProp::LinearProperties(e, system);
            double len = system.Mass();

            if (len < mincurvelength)
              {
                (*testout) << "ignored" << endl;
                continue;
              }

            double localh = len/mparam.segmentsperedge;
            double s0, s1;

            const TopTools_ListOfShape& parent_faces = edge_face_map.FindFromKey(e);

            TopTools_ListIteratorOfListOfShape parent_face_list;

            for(parent_face_list.Initialize(parent_faces); parent_face_list.More(); parent_face_list.Next())
              {
                TopoDS_Face parent_face = TopoDS::Face(parent_face_list.Value());

                int face_index = geom.fmap.FindIndex(parent_face);

                if(face_index >= 1) localh = min(localh,geom.face_maxh[face_index - 1]);
              }

            Handle(Geom_Curve) c = BRep_Tool::Curve(e, s0, s1);

            maxedgelen = max (maxedgelen, len);
            minedgelen = min (minedgelen, len);

            int maxj = max((int) ceil(len/localh), 2);

            for (int j = 0; j <= maxj; j++)
              {
                gp_Pnt pnt = c->Value (s0+double(j)/maxj*(s1-s0));
                mesh.RestrictLocalH (Point3d(pnt.X(), pnt.Y(), pnt.Z()), localh);
              }
          }

        multithread.task = "Setting local mesh size (edge curvature)";

        // setting edge curvature

        int nsections = 20;

        for (int i = 1; i <= nedges && !multithread.terminate; i++)
          {
            double maxcur = 0;
            multithread.percent = 100 * (i-1)/double(nedges);
            TopoDS_Edge edge = TopoDS::Edge (geom.emap(i));
            if (BRep_Tool::Degenerated(edge)) continue;
            double s0, s1;
            Handle(Geom_Curve) c = BRep_Tool::Curve(edge, s0, s1);
            BRepAdaptor_Curve brepc(edge);
            BRepLProp_CLProps prop(brepc, 2, 1e-5);

            for (int j = 1; j <= nsections; j++)
              {
                double s = s0 + j/(double) nsections * (s1-s0);
                prop.SetParameter (s);
                double curvature = 0;
                if(prop.IsTangentDefined())
                  curvature = prop.Curvature();
                if(curvature> maxcur) maxcur = curvature;

                if (curvature >= 1e99)
                  continue;

                gp_Pnt pnt = c->Value (s);

                mesh.RestrictLocalH (Point3d(pnt.X(), pnt.Y(), pnt.Z()), ComputeH (fabs(curvature), mparam));
              }
          }

        multithread.task = "Setting local mesh size (face curvature)";

        // setting face curvature

        int nfaces = geom.fmap.Extent();

        for (int i = 1; i <= nfaces && !multithread.terminate; i++)
          {
            multithread.percent = 100 * (i-1)/double(nfaces);
            TopoDS_Face face = TopoDS::Face(geom.fmap(i));
            TopLoc_Location loc;
            Handle(Geom_Surface) surf = BRep_Tool::Surface (face);
            Handle(Poly_Triangulation) triangulation = BRep_Tool::Triangulation (face, loc);

            if (triangulation.IsNull())
              {
                BRepTools::Clean (geom.shape);
                BRepMesh_IncrementalMesh (geom.shape, 0.01, true);
                triangulation = BRep_Tool::Triangulation (face, loc);
              }

            BRepAdaptor_Surface sf(face, Standard_True);
            // one prop for evaluating and one for derivatives
            BRepLProp_SLProps prop(sf, 0, 1e-5);
            BRepLProp_SLProps prop2(sf, 2, 1e-5);

            int ntriangles = triangulation -> NbTriangles();
            for (int j = 1; j <= ntriangles; j++)
              {
                gp_Pnt p[3];
                gp_Pnt2d par[3];

                for (int k = 1; k <=3; k++)
                  {
                    int n = triangulation->Triangles()(j)(k);
                    p[k-1] = triangulation->Nodes()(n).Transformed(loc);
                    par[k-1] = triangulation->UVNodes()(n);
                  }

                //double maxside = 0;
                //maxside = max (maxside, p[0].Distance(p[1]));
                //maxside = max (maxside, p[0].Distance(p[2]));
                //maxside = max (maxside, p[1].Distance(p[2]));
                //cout << "\rFace " << i << " pos11 ntriangles " << ntriangles << " maxside " << maxside << flush;

                RestrictHTriangle (par[0], par[1], par[2], &prop, &prop2, mesh, 0, 0, mparam);
                //cout << "\rFace " << i << " pos12 ntriangles " << ntriangles << flush;
              }
          }

        // setting close edges

        if (mparam.closeedgefac.has_value())
          {
            multithread.task = "Setting local mesh size (close edges)";

            int sections = 100;

            NgArray<Line> lines(sections*nedges);

            /*
            BoxTree<3> * searchtree =
              new BoxTree<3> (bb.PMin(), bb.PMax());
            */
            BoxTree<3> searchtree(bb.PMin(), bb.PMax());
            
            int nlines = 0;
            for (int i = 1; i <= nedges && !multithread.terminate; i++)
              {
                TopoDS_Edge edge = TopoDS::Edge (geom.emap(i));
                if (BRep_Tool::Degenerated(edge)) continue;

                double s0, s1;
                Handle(Geom_Curve) c = BRep_Tool::Curve(edge, s0, s1);
                BRepAdaptor_Curve brepc(edge);
                BRepLProp_CLProps prop(brepc, 1, 1e-5);
                prop.SetParameter (s0);

                gp_Vec d0 = prop.D1().Normalized();
                double s_start = s0;
                int count = 0;
                for (int j = 1; j <= sections; j++)
                  {
                    double s = s0 + (s1-s0)*(double)j/(double)sections;
                    prop.SetParameter (s);
                    gp_Vec d1 = prop.D1().Normalized();
                    double cosalpha = fabs(d0*d1);
                    if ((j == sections) || (cosalpha < cos(10.0/180.0*M_PI)))
                      {
                        count++;
                        gp_Pnt p0 = c->Value (s_start);
                        gp_Pnt p1 = c->Value (s);
                        lines[nlines].p0 = Point<3> (p0.X(), p0.Y(), p0.Z());
                        lines[nlines].p1 = Point<3> (p1.X(), p1.Y(), p1.Z());

                        Box3d box;
                        box.SetPoint (Point3d(lines[nlines].p0));
                        box.AddPoint (Point3d(lines[nlines].p1));

                        searchtree.Insert (box.PMin(), box.PMax(), nlines+1);
                        nlines++;

                        s_start = s;
                        d0 = d1;
                      }
                  }
              }

            NgArray<int> linenums;

            for (int i = 0; i < nlines; i++)
              {
                multithread.percent = (100*i)/double(nlines);
                Line & line = lines[i];

                Box3d box;
                box.SetPoint (Point3d(line.p0));
                box.AddPoint (Point3d(line.p1));
                double maxhline = max (mesh.GetH(box.PMin()),
                                       mesh.GetH(box.PMax()));
                box.Increase(maxhline);

                double mindist = 1e99;
                linenums.SetSize(0);
                searchtree.GetIntersecting(box.PMin(),box.PMax(),linenums);

                for (int j = 0; j < linenums.Size(); j++)
                  {
                    int num = linenums[j]-1;
                    if (i == num) continue;
                    if ((line.p0-lines[num].p0).Length2() < 1e-15) continue;
                    if ((line.p0-lines[num].p1).Length2() < 1e-15) continue;
                    if ((line.p1-lines[num].p0).Length2() < 1e-15) continue;
                    if ((line.p1-lines[num].p1).Length2() < 1e-15) continue;
                    mindist = min (mindist, line.Dist(lines[num]));
                  }

                mindist /= (*mparam.closeedgefac + VSMALL);

                if (mindist < 1e-3 * bb.Diam())
                  {
                    (*testout) << "extremely small local h: " << mindist
                               << " --> setting to " << 1e-3 * bb.Diam() << endl;
                    (*testout) << "somewhere near " << line.p0 << " - " << line.p1 << endl;
                    mindist = 1e-3 * bb.Diam();
                  }

                mesh.RestrictLocalHLine(line.p0, line.p1, mindist);
              }
          }

        for (auto mspnt : mparam.meshsize_points)
          mesh.RestrictLocalH(mspnt.pnt, mspnt.h);

        multithread.task = savetask;

      }

    mesh.LoadLocalMeshSize (mparam.meshsizefilename);
  }
}

#endif