Ejemplo n.º 1
0
int ON_BrepExtrudeVertex( 
          ON_Brep& brep,
          int vertex_index,
          const ON_Curve& path_curve
          )
{
  ON_3dVector path_vector;
  if ( vertex_index < 0 && vertex_index >= brep.m_V.Count() )
    return false;
  if ( !ON_BrepExtrudeHelper_CheckPathCurve(path_curve,path_vector) )
    return false;
  ON_Curve* c3 = path_curve.Duplicate();
  brep.m_V.Reserve( brep.m_V.Count() + 1 );
  ON_BrepVertex& v0 = brep.m_V[vertex_index];
  ON_BrepVertex& v1 = brep.NewVertex( v0.point + path_vector, 0.0 );
  c3->Translate( v0.point - c3->PointAtStart() );
  int c3i = brep.AddEdgeCurve( c3 );
  ON_BrepEdge& edge = brep.NewEdge( v0, v1, c3i );
  edge.m_tolerance = 0.0;
  return true;
}
Ejemplo n.º 2
0
static
bool SplitSeam( ON_Brep& brep, 
                ON_BrepTrim& trimA, ON_BrepTrim& trimB,
                ON_BrepTrim& prevtrimB,
                ON_BrepTrim& nexttrimB,
                int vcount0 // number of verts before singular fixups
                )
{
  if ( trimA.m_trim_index == trimB.m_trim_index )
    return false;
  if ( trimA.m_trim_index == prevtrimB.m_trim_index )
    return false;
  if ( trimA.m_trim_index == nexttrimB.m_trim_index )
    return false;
  if ( trimB.m_trim_index == prevtrimB.m_trim_index )
    return false;
  if ( trimB.m_trim_index == nexttrimB.m_trim_index )
    return false;
  if ( prevtrimB.m_trim_index == nexttrimB.m_trim_index )
    return false;
  if ( trimA.m_type != ON_BrepTrim::seam )
    return false;
  if ( trimB.m_type != ON_BrepTrim::seam )
    return false;
  if ( trimA.m_ei != trimB.m_ei )
    return false;
  if (    trimA.m_vi[0] != trimB.m_vi[1] 
       && trimA.m_vi[0] < vcount0
       && trimB.m_vi[1] < vcount0 )
    return false;
  if (    trimA.m_vi[1] != trimB.m_vi[0] 
       && trimA.m_vi[1] < vcount0
       && trimB.m_vi[0] < vcount0 )
    return false;
  if ( prevtrimB.m_vi[1] != trimB.m_vi[0] 
       && prevtrimB.m_vi[1] < vcount0
       && trimB.m_vi[0] < vcount0 )
    return false;
  if ( nexttrimB.m_vi[0] != trimB.m_vi[1]
       && prevtrimB.m_vi[0] < vcount0
       && trimB.m_vi[1] < vcount0 )
    return false;
  if ( trimA.m_li != trimB.m_li )
    return false;
  if ( trimA.m_li != prevtrimB.m_li )
    return false;
  if ( trimA.m_li != nexttrimB.m_li )
    return false;
  if ( trimA.m_bRev3d == trimB.m_bRev3d )
    return false;
  const ON_Surface* srf = trimA.SurfaceOf();
  if ( 0 == srf )
    return false;
  ON_BrepEdge* edgeA = brep.Edge(trimA.m_ei);
  if ( 0 == edgeA )
    return false;
  if ( edgeA->m_ti.Count() != 2 )
    return false;
  if ( edgeA->m_ti[0] != trimA.m_trim_index && edgeA->m_ti[1] != trimA.m_trim_index )
    return false;
  if ( edgeA->m_ti[0] != trimB.m_trim_index && edgeA->m_ti[1] != trimB.m_trim_index )
    return false;

  // reserve space now so the vA0 and vA1 pointers
  // will be valid if m_V[] is grown.
  brep.m_V.Reserve( brep.m_V.Count()+2 );

  ON_BrepVertex* vA0 = brep.Vertex(trimA.m_vi[0]);
  if ( 0 == vA0 )
    return false;
  ON_BrepVertex* vA1 = brep.Vertex(trimA.m_vi[1]);
  if ( 0 == vA1 )
    return false;

  // looks like we have a valid seam to blow apart

  // get a new 3d curve for trimB
  ON_Curve* cB3 = PushUpIsoTrim( brep, trimB );
  if ( 0 == cB3 )
    return false;
  int c3i = brep.AddEdgeCurve(cB3);

  vA0->m_tolerance = ON_UNSET_VALUE;
  vA1->m_tolerance = ON_UNSET_VALUE;

  // make new vertices for trimB
  ON_BrepVertex* vB0 = 0;
  ON_BrepVertex* vB1 = 0;

  ON_3dPoint PA, PB;
  bool bSame = false;

  if (brep.GetTrim3dStart(trimB.m_trim_index, PB) && brep.GetTrim3dEnd(trimA.m_trim_index, PA))
    bSame = PB.DistanceTo(PA) < ON_ZERO_TOLERANCE;
  if (bSame || trimB.m_vi[0] != trimA.m_vi[1] )
  {
    // sing fixups have already blown apart this end
    vB0 = brep.Vertex( trimB.m_vi[0] );
  }

  bSame = false;
  if (brep.GetTrim3dStart(trimA.m_trim_index, PA) && brep.GetTrim3dEnd(trimB.m_trim_index, PB))
    bSame = PB.DistanceTo(PA) < ON_ZERO_TOLERANCE;
  if (bSame || trimB.m_vi[1] != trimA.m_vi[0] )
  {
    // sing fixups have already blown apart this end
    vB1 = brep.Vertex( trimB.m_vi[1] );
  }
  if ( 0 == vB0 )
  {
    ON_BrepVertex& v = brep.NewVertex();
    vB0 = &v;
    trimB.m_vi[0] = vB0->m_vertex_index;
  }
  if ( 0 == vB1 )
  {
    ON_BrepVertex& v = brep.NewVertex();
    vB1 = &v;
    trimB.m_vi[1] = vB1->m_vertex_index;
  }

  // disconnect edgeA and trimB
  trimB.m_ei = -1;
  if ( edgeA->m_ti[0] == trimB.m_trim_index )
    edgeA->m_ti.Remove(0);
  else if ( edgeA->m_ti[1] == trimB.m_trim_index )
    edgeA->m_ti.Remove(1);
  ChangeTrimVertex( brep, trimB, 0, vA1->m_vertex_index, vB0->m_vertex_index, true, true );
  ChangeTrimVertex( brep, trimB, 1, vA0->m_vertex_index, vB1->m_vertex_index, true, true );

  ChangeTrimVertex( brep, prevtrimB, 1, vA1->m_vertex_index, vB0->m_vertex_index, true, true );
  ChangeTrimVertex( brep, nexttrimB, 0, vA0->m_vertex_index, vB1->m_vertex_index, true, true );

  // make a new edgeB and connect it to trimB
  ON_BrepEdge& edgeB = brep.NewEdge( *vB0, *vB1, c3i );
  edgeA = 0; // pointer may be invalid after m_E[] grows

  edgeB.m_ti.Append(trimB.m_trim_index);
  trimB.m_ei = edgeB.m_edge_index;
  trimB.m_bRev3d = false;

  trimA.m_type = ON_BrepTrim::boundary;
  trimB.m_type = ON_BrepTrim::boundary;

  return true;
}
Ejemplo n.º 3
0
static
bool ChangeTrimSingToBdry( ON_Brep& brep, ON_BrepTrim& trim, ON_BrepTrim* nexttrim )
{
  if ( trim.m_vi[0] != trim.m_vi[1] )
    return false;
  if ( trim.m_type != ON_BrepTrim::singular )
    return false;
  if ( trim.m_ei >= 0 )
    return false;

  const ON_Surface* srf = trim.SurfaceOf();
  if ( 0 == srf )
    return false;

  brep.m_V.Reserve( brep.m_V.Count() + 1 );
  ON_BrepVertex* v0 = brep.Vertex(trim.m_vi[0]);
  if ( 0 == v0 )
    return false;

  // get new 3d curve
  ON_Curve* c3 = PushUpIsoTrim( brep, trim );
  if ( 0 == c3 )
    return false;

  // valid singular trim can be changed to non-singular trim


  // create new vertex for end of this trim
  v0->m_tolerance = ON_UNSET_VALUE;

  ON_BrepVertex* v1 = 0;

  if ( c3->IsClosed() )
  {
    // 3d edge is closed so start and end vertex are still the same.
    v1 = v0;
  }
  else
  {
    // new 3d edge is not closed, so the single singular vertex
    // needs to be "split" into two vertices.
    brep.NewVertex();
    v1 = brep.m_V.Last();
  }
  trim.m_vi[1] = v1->m_vertex_index;

  // update the start of the next trim to use new vertex
  if ( nexttrim && nexttrim->m_trim_index != trim.m_trim_index )
  {
    ChangeTrimVertex( brep, *nexttrim, 0, v0->m_vertex_index, v1->m_vertex_index, true, true );
  }              

  // make a new edge
  int ci = brep.AddEdgeCurve(c3);
  c3 = 0;
  ON_BrepEdge& edge = brep.NewEdge(*v0,*v1,ci);
  edge.m_tolerance = 0.0;

  // hook trim to new edge
  trim.m_type = ON_BrepTrim::boundary;
  trim.m_bRev3d = false;
  trim.m_ei = edge.m_edge_index;
  edge.m_ti.Append(trim.m_trim_index);

  return true;
}
Ejemplo n.º 4
0
bool ON_BrepExtrude( 
          ON_Brep& brep,
          const ON_Curve& path_curve,
          bool bCap
          )
{
  ON_Workspace ws;
  const int vcount0 = brep.m_V.Count();
  const int tcount0 = brep.m_T.Count();
  const int lcount0 = brep.m_L.Count();
  const int ecount0 = brep.m_E.Count();
  const int fcount0 = brep.m_F.Count();

  const ON_3dPoint PathStart = path_curve.PointAtStart();
  ON_3dPoint P = path_curve.PointAtEnd();
  if ( !PathStart.IsValid() || !P.IsValid() )
    return false;
  const ON_3dVector height = P - PathStart;
  if ( !height.IsValid() || height.Length() <= ON_ZERO_TOLERANCE )
    return false;

  ON_Xform tr;
  tr.Translation(height);

  // count number of new sides
  int side_count = 0;
  int i, vi, ei, fi;
  bool* bSideEdge = (bool*)ws.GetIntMemory(ecount0*sizeof(bSideEdge[0]));
  for ( ei = 0; ei < ecount0; ei++ )
  {
    const ON_BrepEdge& e = brep.m_E[ei];
    if ( 1 == e.m_ti.Count() )
    {
      side_count++;
      bSideEdge[ei] = true;
    }
    else
    {
      bSideEdge[ei] = false;
    }
  }

  brep.m_V.Reserve( 2*vcount0 );
  i = 4*side_count + (bCap?tcount0:0);
  brep.m_T.Reserve( tcount0 + i );
  brep.m_C2.Reserve( brep.m_C2.Count() + i );
  brep.m_L.Reserve( lcount0 + side_count + (bCap?lcount0:0) );
  i = side_count + (bCap?ecount0:side_count);
  brep.m_E.Reserve( ecount0 + i );
  brep.m_C3.Reserve( brep.m_C3.Count() + i );
  i = side_count + (bCap?fcount0:0);
  brep.m_F.Reserve( fcount0 + i );
  brep.m_S.Reserve( brep.m_S.Count() + i );

  bool bOK = true;

  // build top vertices
  int* topvimap = ws.GetIntMemory(vcount0);
  memset(topvimap,0,vcount0*sizeof(topvimap[0]));
  if ( bCap )
  {
    for ( vi = 0; vi < vcount0; vi++ )
    {
      const ON_BrepVertex& bottomv = brep.m_V[vi];
      ON_BrepVertex& topv = brep.NewVertex(bottomv.point+height,bottomv.m_tolerance);
      topvimap[vi] = topv.m_vertex_index;
    }
  }
  else
  {
    for ( ei = 0; ei < ecount0; ei++ )
    {
      if ( bSideEdge[ei] )
      {
        const ON_BrepEdge& bottome = brep.m_E[ei];
        int bottomvi0 = bottome.m_vi[0];
        if ( bottomvi0 < 0 || bottomvi0 >= vcount0 )
        {
          bOK = false;
          break;
        }
        int bottomvi1 = bottome.m_vi[1];
        if ( bottomvi1 < 0 || bottomvi1 >= vcount0 )
        {
          bOK = false;
          break;
        }
        if ( !topvimap[bottomvi0] )
        {
          const ON_BrepVertex& bottomv = brep.m_V[bottomvi0];
          ON_BrepVertex& topv = brep.NewVertex(bottomv.point+height,bottomv.m_tolerance);
          topvimap[bottomvi0] = topv.m_vertex_index;
        }
        if ( !topvimap[bottomvi1] )
        {
          const ON_BrepVertex& bottomv = brep.m_V[bottomvi1];
          ON_BrepVertex& topv = brep.NewVertex(bottomv.point+height,bottomv.m_tolerance);
          topvimap[bottomvi1] = topv.m_vertex_index;
        }
      }
    }
  }

  // build top edges
  int* topeimap = ws.GetIntMemory(ecount0);
  memset(topeimap,0,ecount0*sizeof(topeimap[0]));
  if ( bOK ) for ( ei = 0; ei < ecount0; ei++ )
  {
    if ( bCap || bSideEdge[ei] )
    {
      const ON_BrepEdge& bottome = brep.m_E[ei];
      ON_BrepVertex& topv0 = brep.m_V[topvimap[bottome.m_vi[0]]];
      ON_BrepVertex& topv1 = brep.m_V[topvimap[bottome.m_vi[1]]];
      ON_Curve* c3 = bottome.DuplicateCurve();
      if ( !c3 )
      {
        bOK = false;
        break;
      }
      c3->Transform(tr);
      int c3i = brep.AddEdgeCurve(c3);
      ON_BrepEdge& tope = brep.NewEdge(topv0,topv1,c3i,0,bottome.m_tolerance);
      topeimap[ei] = tope.m_edge_index;
    }
  }

  // build side edges
  int* sideveimap = ws.GetIntMemory(vcount0);
  memset(sideveimap,0,vcount0*sizeof(sideveimap[0]));
  if ( bOK ) for ( vi = 0; vi < vcount0; vi++ )
  {
    ON_BrepVertex& bottomv = brep.m_V[vi];
    for ( int vei = 0; vei < bottomv.m_ei.Count(); vei++ )
    {
      if ( bSideEdge[bottomv.m_ei[vei]] && topvimap[vi] )
      {
        ON_BrepVertex& topv = brep.m_V[topvimap[vi]];
        ON_Curve* c3 = path_curve.DuplicateCurve();
        if ( !c3 )
        {
          bOK = false;
        }
        else
        {
          ON_3dVector D = bottomv.point - PathStart;
          c3->Translate(D);
          int c3i = brep.AddEdgeCurve(c3);
          const ON_BrepEdge& e = brep.NewEdge(bottomv,topv,c3i,0,0.0);
          sideveimap[vi] = e.m_edge_index;
        }
        break;
      }
    }
  }

  if ( bOK && bCap )
  {
    // build top faces
    for (fi = 0; fi < fcount0; fi++ )
    {
      const ON_BrepFace& bottomf = brep.m_F[fi];
      ON_Surface* srf = bottomf.DuplicateSurface();
      if ( !srf )
      {
        bOK = false;
        break;
      }
      srf->Transform(tr);
      int si = brep.AddSurface(srf);
      ON_BrepFace& topf = brep.NewFace(si);
      topf.m_bRev = !bottomf.m_bRev;
      const int loop_count = bottomf.m_li.Count();
      topf.m_li.Reserve(loop_count);
      for ( int fli = 0; fli < loop_count; fli++ )
      {
        const ON_BrepLoop& bottoml = brep.m_L[bottomf.m_li[fli]];
        ON_BrepLoop& topl = brep.NewLoop(bottoml.m_type,topf);
        const int loop_trim_count = bottoml.m_ti.Count();
        topl.m_ti.Reserve(loop_trim_count);
        for ( int lti = 0; lti < loop_trim_count; lti++ )
        {
          const ON_BrepTrim& bottomt = brep.m_T[bottoml.m_ti[lti]];
          ON_NurbsCurve* c2 = ON_NurbsCurve::New();
          if ( !bottomt.GetNurbForm(*c2) )
          {
            delete c2;
            bOK = false;
            break;
          }
          int c2i = brep.AddTrimCurve(c2);
          ON_BrepTrim* topt = 0;
          if ( bottomt.m_ei >= 0 )
          {
            ON_BrepEdge& tope = brep.m_E[topeimap[bottomt.m_ei]];
            topt = &brep.NewTrim(tope,bottomt.m_bRev3d,topl,c2i);
          }
          else
          {
            // singular trim
            ON_BrepVertex& topv = brep.m_V[topvimap[bottomt.m_vi[0]]];
            topt = &brep.NewSingularTrim(topv,topl,bottomt.m_iso,c2i);
          }
          topt->m_tolerance[0] = bottomt.m_tolerance[0];
          topt->m_tolerance[1] = bottomt.m_tolerance[1];
          topt->m_pbox = bottomt.m_pbox;
          topt->m_type = bottomt.m_type;
          topt->m_iso = bottomt.m_iso;
        }
        topl.m_pbox = bottoml.m_pbox;
      }
    }
  }

  // build sides
  int bRev3d[4] = {0,0,1,1};
  int vid[4], eid[4];
  if( bOK ) for ( ei = 0; ei < ecount0; ei++ )
  {
    if ( bSideEdge[ei] && topeimap[ei] )
    {
      ON_BrepEdge& bottome = brep.m_E[ei];
      ON_BrepEdge& tope = brep.m_E[topeimap[ei]];
      vid[0] = bottome.m_vi[0];
      vid[1] = bottome.m_vi[1];
      vid[2] = topvimap[vid[1]];
      vid[3] = topvimap[vid[0]];
      if ( sideveimap[vid[0]] && sideveimap[vid[1]] )
      {
        ON_BrepEdge& leftedge = brep.m_E[sideveimap[vid[0]]];
        ON_BrepEdge& rightedge = brep.m_E[sideveimap[vid[1]]];
        ON_Curve* cx = bottome.DuplicateCurve();
        if ( !cx )
        {
          bOK = false;
          break;
        }
        ON_Curve* cy = leftedge.DuplicateCurve();
        if ( !cy )
        {
          delete cx;
          bOK = false;
          break;
        }
        ON_SumSurface* srf = new ON_SumSurface();
        srf->m_curve[0] = cx;
        srf->m_curve[1] = cy;
        srf->m_basepoint = srf->m_curve[1]->PointAtStart();
        srf->m_basepoint.x = -srf->m_basepoint.x;
        srf->m_basepoint.y = -srf->m_basepoint.y;
        srf->m_basepoint.z = -srf->m_basepoint.z;
        eid[0] = bottome.m_edge_index;
        eid[1] = rightedge.m_edge_index;
        eid[2] = tope.m_edge_index;
        eid[3] = leftedge.m_edge_index;
        ON_BrepFace* face = brep.NewFace(srf,vid,eid,bRev3d);
        if ( !face )
        {
          bOK = false;
          break;
        }
        else if ( bottome.m_ti.Count() == 2 )
        {
          const ON_BrepTrim& trim0 = brep.m_T[bottome.m_ti[0]];
          const ON_BrepTrim& trim1 = brep.m_T[bottome.m_ti[1]];
          const ON_BrepLoop& loop0 = brep.m_L[trim0.m_li];
          const ON_BrepLoop& loop1 = brep.m_L[trim1.m_li];
          bool bBottomFaceRev = brep.m_F[(loop0.m_fi != face->m_face_index) ? loop0.m_fi : loop1.m_fi].m_bRev;
          bool bSideFaceRev = ( trim0.m_bRev3d != trim1.m_bRev3d ) 
                            ? bBottomFaceRev 
                            : !bBottomFaceRev;
          face->m_bRev = bSideFaceRev;
        }
      }
    }
  }

  if ( !bOK )
  {
    for ( vi = brep.m_V.Count(); vi >= vcount0; vi-- )
    {
      brep.DeleteVertex(brep.m_V[vi]);
    }
  }

  return bOK;
}
Ejemplo n.º 5
0
static 
bool ON_BrepExtrudeHelper_MakeTopLoop( 
          ON_Brep& brep, 
          ON_BrepFace& top_face,
          int bottom_loop_index,
          const ON_3dVector path_vector,
          const int* side_face_index // array of brep.m_L[bottom_loop_index].m_ti.Count() face indices
          )
{
  bool rc = true;

  int lti, top_trim_index, i;
  if ( bottom_loop_index < 0 || bottom_loop_index >= brep.m_L.Count() )
    return false;
  ON_BrepLoop::TYPE loop_type = brep.m_L[bottom_loop_index].m_type;
  if ( loop_type != ON_BrepLoop::inner )
    loop_type = ON_BrepLoop::outer;
  ON_BrepLoop& top_loop = brep.NewLoop( loop_type, top_face );
  const ON_BrepLoop& bottom_loop = brep.m_L[bottom_loop_index];
  const int loop_trim_count = bottom_loop.m_ti.Count();
  brep.m_T.Reserve( brep.m_T.Count() + loop_trim_count );

  // Set top_vertex_index[lti] = index of vertex above 
  // vertex brep.m_V[brep.m_T[bottom_loop.m_ti[lti]].m_vi[0]].
  // Set top_vertex_index[lti] = index of edge above 
  // edge of brep.m_T[bottom_loop.m_ti[lti]].
  // This informtion is needed for singular and seam trims.
  ON_SimpleArray<int> top_vertex_index(loop_trim_count);
  ON_SimpleArray<int> top_edge_index(loop_trim_count);
  ON_SimpleArray<bool> top_trim_bRev3d(loop_trim_count);
  for ( lti = 0; lti < loop_trim_count; lti++ )
  {
    top_vertex_index.Append(-1);
    top_edge_index.Append(-1);
    top_trim_bRev3d.Append(false);
  }

  // some (often all of) of the "top" vertices are already on
  // the side faces
  for ( lti = 0; lti < loop_trim_count; lti++ )
  {
    if ( side_face_index[lti] >= 0 )
    {
      const ON_BrepFace& side_face = brep.m_F[side_face_index[lti]];
      const ON_BrepLoop& side_loop = brep.m_L[side_face.m_li[0]];
      const ON_BrepTrim& side_north_trim = brep.m_T[side_loop.m_ti[2]];
      top_vertex_index[lti] = side_north_trim.m_vi[0];
      top_vertex_index[(lti+1)%loop_trim_count] = side_north_trim.m_vi[1];
      top_edge_index[lti] = side_north_trim.m_ei;
    }
    else 
    {
      // fix for RR 20423
      int lti_prev = (lti+loop_trim_count-1)%loop_trim_count;
      int lti_next = (lti+1)%loop_trim_count;
      if (   side_face_index[lti_prev] < 0 
           && side_face_index[lti_next] < 0 
           && top_vertex_index[lti] < 0
           && top_vertex_index[lti_next] < 0
           )
      {
        int bottom_ti_prev = bottom_loop.m_ti[lti_prev];
        int bottom_ti      = bottom_loop.m_ti[lti];
        int bottom_ti_next = bottom_loop.m_ti[lti_next];
        if (    bottom_ti >= 0      && bottom_ti < brep.m_T.Count() 
             && bottom_ti_prev >= 0 && bottom_ti_prev < brep.m_T.Count() 
             && bottom_ti_next >= 0 && bottom_ti_next < brep.m_T.Count() 
           )
        {
          const ON_BrepTrim& bottom_trim_prev = brep.m_T[bottom_ti_prev];
          const ON_BrepTrim& bottom_trim = brep.m_T[bottom_ti];
          const ON_BrepTrim& bottom_trim_next = brep.m_T[bottom_ti_next];
          if (    ON_BrepTrim::seam == bottom_trim_prev.m_type
               && ON_BrepTrim::singular == bottom_trim.m_type
               && ON_BrepTrim::seam == bottom_trim_next.m_type 
               && bottom_trim.m_vi[0] == bottom_trim.m_vi[1]
               )
          {
            int vi = bottom_trim.m_vi[0];
            if ( vi >= 0 && vi < brep.m_V.Count() )
            {
              ON_BrepVertex& top_vertex = brep.NewVertex(brep.m_V[vi].point+path_vector,0.0);
              top_vertex_index[lti] = top_vertex.m_vertex_index;
              top_vertex_index[lti_next] = top_vertex_index[lti];
            }
          }
        }
      }
    }
  }

  // Fill in the missing "top" vertices that
  // are associated with singular and trim edges by looking
  // at their neighbors.
  {
    bool bKeepChecking = true;
    while( bKeepChecking )
    {
      // set back to true if we make a change.  This handles the
      // (very rare) cases of multiple adjacent singular trims.
      bKeepChecking = false; 

      for ( lti = 0; lti < loop_trim_count; lti++ )
      {
        if ( top_vertex_index[lti] == -1 )
        {
          for ( i = lti+1; i < loop_trim_count; i++ )
          {
            if ( ON_BrepTrim::singular != brep.m_T[bottom_loop.m_ti[i-1]].m_type )
              break;
            if ( top_vertex_index[i] >= 0 )
            {
              top_vertex_index[lti] = top_vertex_index[i];
              bKeepChecking = true; 
              break;
            }
          }
        }

        if ( top_vertex_index[lti] == -1 )
        {
          for ( i = lti-1; i >= 0; i-- )
          {
            if ( ON_BrepTrim::singular != brep.m_T[bottom_loop.m_ti[i+1]].m_type )
              break;
            if ( top_vertex_index[i] >= 0 )
            {
              top_vertex_index[lti] = top_vertex_index[i];
              bKeepChecking = true; 
              break;
            }
          }
        }
      }
    }
  }

  // Fill in missing edges of "seam" trims.
  for ( lti = 0; lti < loop_trim_count; lti++ )
  {
    if ( -1 != top_edge_index[lti] )
      continue;
    int bottom_ti = bottom_loop.m_ti[lti];
    if ( bottom_ti < 0 || bottom_ti >= brep.m_T.Count() )
      continue;
    const ON_BrepTrim& bottom_trim = brep.m_T[bottom_ti];
    if ( ON_BrepTrim::seam != bottom_trim.m_type )
      continue;
    if ( bottom_trim.m_ei < 0 )
      continue;
    if ( bottom_trim.m_ei >= brep.m_E.Count() )
      continue;

    // duplicate bottom edge curve
    const ON_BrepEdge& bottom_edge = brep.m_E[bottom_trim.m_ei];
    ON_Curve* top_c3 = bottom_edge.DuplicateCurve();
    if ( 0 == top_c3 )
      continue;
    // move new edge curve to top location
    top_c3->Translate(path_vector);
    ON_3dPoint P0 = top_c3->PointAtStart();
    ON_3dPoint P1 = top_c3->PointAtEnd();
    int top_c3i = brep.AddEdgeCurve(top_c3);
    top_c3 = 0;
    // get vertices at start/end of the new edge
    int e_vi0 = top_vertex_index[lti];
    int e_vi1 = top_vertex_index[(lti+1)%loop_trim_count];
    if ( bottom_trim.m_bRev3d )
    {
      // put points in trim order
      ON_3dPoint tmp_P = P0; P0 = P1; P1 = tmp_P;
    }
    if ( e_vi0 < 0 )
    {
      e_vi0 = brep.NewVertex(P0).m_vertex_index;
      top_vertex_index[lti] = e_vi0;
    }
    if ( e_vi1 < 0 )
    {
      e_vi1 = brep.NewVertex(P1).m_vertex_index;
      top_vertex_index[(lti+1)%loop_trim_count] = e_vi1;
    }
    if ( bottom_trim.m_bRev3d )
    {
      // put edge vertex indices in edge order
      int tmp_i = e_vi0; e_vi0 = e_vi1; e_vi1 = tmp_i;
    }
    ON_BrepEdge& top_edge = brep.NewEdge(brep.m_V[e_vi0],brep.m_V[e_vi1],top_c3i);
    top_edge.m_tolerance = bottom_edge.m_tolerance;
    top_edge_index[lti] = top_edge.m_edge_index;
    top_trim_bRev3d[lti] = bottom_trim.m_bRev3d?true:false;

    // find seam mate and set it's 
    // top_edge_index[] to top_edge.m_edge_index.
    int mate_lti;
    for( mate_lti = lti+1; mate_lti < loop_trim_count; mate_lti++ )
    {
      if ( top_edge_index[mate_lti] != -1  )
        continue;
      int bottom_mate_ti = bottom_loop.m_ti[mate_lti];
      if ( bottom_mate_ti < 0 || bottom_mate_ti >= brep.m_T.Count() )
        continue;
      const ON_BrepTrim& bottom_mate_trim = brep.m_T[bottom_mate_ti];
      if ( bottom_mate_trim.m_type != ON_BrepTrim::seam )
        continue;
      if ( bottom_mate_trim.m_ei != bottom_trim.m_ei )
        continue;
      top_edge_index[mate_lti] = top_edge.m_edge_index;
      top_trim_bRev3d[mate_lti] = bottom_mate_trim.m_bRev3d?true:false;
      break;
    }
  }


  for ( lti = 0; lti < loop_trim_count; lti++ )
  {
    const ON_BrepTrim& bottom_trim = brep.m_T[ bottom_loop.m_ti[lti] ];
    ON_Curve* top_c2 = bottom_trim.DuplicateCurve();
    int top_c2i = (0!=top_c2) ? brep.AddTrimCurve(top_c2) : bottom_trim.m_c2i;
    top_trim_index = -1;
    if ( bottom_trim.m_type == ON_BrepTrim::singular && top_vertex_index[lti] >= 0 )
    {
      top_trim_index = brep.NewSingularTrim(brep.m_V[top_vertex_index[lti]], top_loop, bottom_trim.m_iso, top_c2i ).m_trim_index;
    }
    else if ( bottom_trim.m_type != ON_BrepTrim::singular && top_edge_index[lti] >= 0 && top_edge_index[lti] < brep.m_E.Count() )
    {
      ON_BrepEdge& top_edge = brep.m_E[top_edge_index[lti]];
      top_trim_index = brep.NewTrim( top_edge, top_trim_bRev3d[lti], top_loop, top_c2i ).m_trim_index;
    }
    else
    {
      ON_ERROR("ON_BrepExtrudeHelper_MakeTopLoop ran into capping trouble.");
      rc = false;
      break;
    }
    ON_BrepTrim& top_trim = brep.m_T[top_trim_index];
    top_trim.m_pline = bottom_trim.m_pline;
    top_trim.m_pbox = bottom_trim.m_pbox;
    top_trim.m_iso = bottom_trim.m_iso;
    top_trim.m_type = bottom_trim.m_type;
    top_trim.m_tolerance[0] = bottom_trim.m_tolerance[0];
    top_trim.m_tolerance[1] = bottom_trim.m_tolerance[1];
    top_trim.m__legacy_2d_tol = bottom_trim.m__legacy_2d_tol;
    top_trim.m__legacy_3d_tol = bottom_trim.m__legacy_2d_tol;
    top_trim.m__legacy_flags = bottom_trim.m__legacy_flags;
  }
  if (rc)
  {
    top_loop.m_pbox = bottom_loop.m_pbox;
  }
  return rc;
}