vcglib/vcg/complex/algorithms/clip.h

/****************************************************************************
* VCGLib                                                            o o     *
* Visual and Computer Graphics Library                            o     o   *
*                                                                _   O  _   *
* Copyright(C) 2004-2016                                           \/)\/    *
* Visual Computing Lab                                            /\/|      *
* ISTI - Italian National Research Council                           |      *
*                                                                    \      *
* All rights reserved.                                                      *
*                                                                           *
* This program is free software; you can redistribute it and/or modify      *
* it under the terms of the GNU General Public License as published by      *
* the Free Software Foundation; either version 2 of the License, or         *
* (at your option) any later version.                                       *
*                                                                           *
* This program is distributed in the hope that it will be useful,           *
* but WITHOUT ANY WARRANTY; without even the implied warranty of            *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             *
* GNU General Public License (http://www.gnu.org/licenses/gpl.txt)          *
* for more details.                                                         *
*                                                                           *
****************************************************************************/

#ifndef __VCGLIB_TRI_CLIP
#define __VCGLIB_TRI_CLIP
#include <unordered_map>
#include <vcg/complex/complex.h>

namespace vcg
{
namespace tri
{

  template <typename MESH_TYPE>
  class GenericVertexInterpolator
  {
  public:
    typedef typename MESH_TYPE::VertexType VertexType;
    typedef GenericVertexInterpolator<MESH_TYPE> ClassType;
    typedef typename VertexType::CoordType CoordType;
    typedef typename CoordType::ScalarType ScalarType;
    GenericVertexInterpolator(MESH_TYPE &_m) : m(_m) {}
  private:
    MESH_TYPE &m;
  public:
    inline void operator () (const VertexType & v0, const VertexType & v1, const VertexType & v2, const ScalarType & a, const ScalarType & b, VertexType & r) const
    {
      // position
      r.P() = v0.cP() + (v1.cP() - v0.cP()) * a + (v2.cP() - v0.cP()) * b;

      // normal
      if (tri::HasPerVertexNormal(m))
      {
        r.N() = v0.cN() + (v1.cN() - v0.cN()) * a + (v2.cN() - v0.cN()) * b;
      }

      // color
      if (tri::HasPerVertexColor(m))
      {
        vcg::Point4<ScalarType> vc[3];
        vc[0].Import(v0.cC());
        vc[1].Import(v1.cC());
        vc[2].Import(v2.cC());
        const vcg::Point4<ScalarType> rc = (vc[0] + (vc[1] - vc[0]) * a + (vc[2] - vc[0]) * b);
        r.C()[0] = (typename vcg::Color4b::ScalarType)(rc[0]);
        r.C()[1] = (typename vcg::Color4b::ScalarType)(rc[1]);
        r.C()[2] = (typename vcg::Color4b::ScalarType)(rc[2]);
        r.C()[3] = (typename vcg::Color4b::ScalarType)(rc[3]);
      }

      // texcoord
      if (tri::HasPerVertexTexCoord(m))
      {
        const short nt = 1; //typename VertexType::TextureType::N();
        for (short i=0; i<nt; ++i)
        {
          r.T().t(i) = v0.cT().t(i) + (v1.cT().t(i) - v0.cT().t(i)) * a + (v2.cT().t(i) - v0.cT().t(i)) * b;
        }
      }
    }
  };
template <typename TRIMESHTYPE>
class TriMeshClipper
{
public:

  typedef TriMeshClipper<TRIMESHTYPE> ClassType;
  typedef TRIMESHTYPE TriMeshType;
  typedef typename TriMeshType::FaceType FaceType;
  typedef typename FaceType::VertexType VertexType;
  typedef typename VertexType::CoordType CoordType;
  typedef typename CoordType::ScalarType ScalarType;

  /*
    static inline void Box(const Box3<ScalarType> & b, VERTEXINTEPOLATOR & vInterp, TriMeshType & m);

    Clip mesh "m" against an axis aligned box (in place version);

    Notes:
      1) faces marked as deleted are skipped;
      2) faces completely outside box are marked as deleted;
      3) faces completely inside box are left unchanged;
      4) faces intersecting box's sides are marked as deleted:
         they are replaced with proper tesselation; new vertices and faces
         are created, so reallocation could occour; previously saved pointers
         could not to be valid anymore, thus they should be updated;
      5) vInterp functor must implement a n operator with signature
             void operator () (const VERTEX & v0, const VERTEX & v1, const VERTEX & v2, const Scalar & a, const Scalar & b, VERTEX & r);
         its semantic is to intepolate vertex attribute across triangle; a typical implementation is;
           r.P() = v0.P() + a * (v1.P() - v0.P()) + b * (v2.P() - v0.P());  // interpolate position
           r.N() = v0.N() + a * (v1.N() - v0.N()) + b * (v2.N() - v0.N());  // interpolate normal
           ...    // interpolate other vertex attributes
  */
  template <class ScalarType>
      class VertexClipInfo
  {
  public:
//			typedef VertexClipInfo ClassType;

    ScalarType fU;
    ScalarType fV;
    unsigned int idx;
    unsigned int tref;
  };
  typedef typename std::vector< VertexClipInfo<ScalarType> > VertexClipInfoVec;
  class TriangleInfo
  {
  public:
    typedef TriangleInfo ClassType;

    unsigned int v[3];
    unsigned int idx;
  };

  typedef std::vector<TriangleInfo> TriangleInfoVec;

  class EdgeIsect
  {
  public:
    CoordType p;
    unsigned int idx;
  };

  template <typename VERTEXINTEPOLATOR>
  static inline void Box(const Box3<ScalarType> & b, VERTEXINTEPOLATOR & vInterp, TriMeshType & m)
  {
    std::vector<unsigned int> facesToDelete;
    ClassType::Box(b, vInterp, m, facesToDelete);
    for (size_t i=0; i<facesToDelete.size(); ++i)
    {
      m.face[facesToDelete[i]].SetD();
    }
  }

  class EdgeIntersections
  {
  public:
    unsigned int n;
    EdgeIsect isects[6];

    EdgeIntersections(void)
    {
      this->n = 0;
    }
  };

  typedef std::unordered_map<unsigned int, EdgeIntersections> UIntHMap;
  typedef typename UIntHMap::iterator UIntHMap_i;
  typedef typename UIntHMap::value_type UIntHMap_v;

  typedef std::unordered_map<unsigned int, UIntHMap> EdgeMap;
  typedef typename EdgeMap::iterator EdgeMap_i;
  typedef typename EdgeMap::value_type EdgeMap_v;

  typedef typename TriMeshType::FaceIterator FaceIterator;

  template <typename VERTEXINTEPOLATOR, typename FACEINDEXCONTAINER>
  static inline void Box(const Box3<ScalarType> & b, VERTEXINTEPOLATOR & vInterp, TriMeshType & m, FACEINDEXCONTAINER & facesToDelete)
  {
    if (m.fn <= 0)
    {
      return;
    }

    EdgeMap edges;
    VertexClipInfoVec vInfos;
    TriangleInfoVec tInfos;

    CoordType vTriangle[4];
    CoordType vClipped[64];

    CoordType pvP0[64];
    CoordType pvP1[64];

    unsigned int numDeletedTris = 0;
    unsigned int numTriangles = 0;
    unsigned int numVertices = 0;

    unsigned int vIdx = (unsigned int)(m.vn);
    unsigned int tIdx = (unsigned int)(m.fn);

    ScalarType boxOffsets[6];

    boxOffsets[0] =  b.min[0];
    boxOffsets[1] = -b.max[0];
    boxOffsets[2] =  b.min[1];
    boxOffsets[3] = -b.max[1];
    boxOffsets[4] =  b.min[2];
    boxOffsets[5] = -b.max[2];

    UIntHMap emptyMap;
    EdgeIntersections emptyIsects;

    const ScalarType eps = (ScalarType)(1e-6);

    for (FaceIterator it=m.face.begin(); it!=m.face.end(); ++it)
    {
      if ((*it).IsD())
      {
        continue;
      }

      unsigned int cc[3];

      cc[0] = ClassType::BoxClipCode(boxOffsets, (*it).V(0)->P());
      cc[1] = ClassType::BoxClipCode(boxOffsets, (*it).V(1)->P());
      cc[2] = ClassType::BoxClipCode(boxOffsets, (*it).V(2)->P());

      if ((cc[0] | cc[1] | cc[2]) == 0)
      {
        continue;
      }

      const unsigned int refT = (unsigned int)(std::distance(m.face.begin(), it));

      if ((cc[0] & cc[1] & cc[2]) != 0)
      {
        facesToDelete.push_back(refT);
        (*it).SetD();
        numDeletedTris++;
        continue;
      }

      facesToDelete.push_back(refT);

      vTriangle[0] = (*it).V(0)->P();
      vTriangle[1] = (*it).V(1)->P();
      vTriangle[2] = (*it).V(2)->P();
      vTriangle[3] = (*it).V(0)->P();

      unsigned int n, n0, n1;

      ClipPolygonLine(0, b.min[0], vTriangle,  4, pvP1,     n1);
      ClipPolygonLine(1, b.max[0], pvP1,      n1, pvP0,     n0);

      ClipPolygonLine(2, b.min[1], pvP0,      n0, pvP1,     n1);
      ClipPolygonLine(3, b.max[1], pvP1,      n1, pvP0,     n0);

      ClipPolygonLine(4, b.min[2], pvP0,      n0, pvP1,     n1);
      ClipPolygonLine(5, b.max[2], pvP1,      n1, vClipped,  n);

      assert(n < 64);

      unsigned int firstV, lastV;

      if (n > 2)
      {
        if (vClipped[0] == vClipped[n - 1])
        {
          n--;
        }

        const CoordType vU = vTriangle[1] - vTriangle[0];
        const CoordType vV = vTriangle[2] - vTriangle[0];

        const ScalarType tArea = (vU ^ vV).SquaredNorm();
        if (tArea < eps)
        {
          continue;
        }

        unsigned int tvidx[3];
        tvidx[0] = (*it).V(0) - &(*(m.vert.begin()));
        tvidx[1] = (*it).V(1) - &(*(m.vert.begin()));
        tvidx[2] = (*it).V(2) - &(*(m.vert.begin()));

        numTriangles += n - 2;

//				size_t vBegin = vInfos.size();

        VertexClipInfo<ScalarType> vnfo;
        TriangleInfo tnfo;

        unsigned int vmin[3];
        unsigned int vmax[3];

        if (tvidx[0] < tvidx[1])
        {
          vmin[0] = tvidx[0];
          vmax[0] = tvidx[1];
        }
        else
        {
          vmin[0] = tvidx[1];
          vmax[0] = tvidx[0];
        }

        if (tvidx[0] < tvidx[2])
        {
          vmin[1] = tvidx[0];
          vmax[1] = tvidx[2];
        }
        else
        {
          vmin[1] = tvidx[2];
          vmax[1] = tvidx[0];
        }

        if (tvidx[1] < tvidx[2])
        {
          vmin[2] = tvidx[1];
          vmax[2] = tvidx[2];
        }
        else
        {
          vmin[2] = tvidx[2];
          vmax[2] = tvidx[1];
        }

        for (unsigned int i=0; i<n; ++i)
        {
          vnfo.tref = refT;

          const CoordType vP = vClipped[i] - vTriangle[0];

          ScalarType tAreaU = (vU ^ vP).SquaredNorm();
          ScalarType tAreaV = (vP ^ vV).SquaredNorm();

          vnfo.fU = (ScalarType)(sqrt(tAreaU / tArea));
          vnfo.fV = (ScalarType)(sqrt(tAreaV / tArea));

          if (vClipped[i] == vTriangle[0])
          {
            vnfo.idx = tvidx[0];
          }
          else if (vClipped[i] == vTriangle[1])
          {
            vnfo.idx = tvidx[1];
          }
          else if (vClipped[i] == vTriangle[2])
          {
            vnfo.idx = tvidx[2];
          }
          else if (vnfo.fV < eps)
          {
            std::pair<EdgeMap_i, bool> mi = edges.insert(std::make_pair(vmin[1], emptyMap));
            std::pair<UIntHMap_i, bool> hi = (*(mi.first)).second.insert(std::make_pair(vmax[1], emptyIsects));
            bool found = false;
            for (unsigned int s=0; s<(*(hi.first)).second.n; ++s)
            {
              if (vClipped[i] == (*(hi.first)).second.isects[s].p)
              {
                found = true;
                vnfo.idx = (*(hi.first)).second.isects[s].idx;
                break;
              }
            }
            if (!found)
            {
              vnfo.idx = vIdx++;
              numVertices++;
              vInfos.push_back(vnfo);

              (*(hi.first)).second.isects[(*(hi.first)).second.n].p = vClipped[i];
              (*(hi.first)).second.isects[(*(hi.first)).second.n].idx = vnfo.idx;
              (*(hi.first)).second.n++;
            }
          }
          else if (vnfo.fU < eps)
          {
            std::pair<EdgeMap_i, bool> mi = edges.insert(std::make_pair(vmin[0], emptyMap));
            std::pair<UIntHMap_i, bool> hi = (*(mi.first)).second.insert(std::make_pair(vmax[0], emptyIsects));
            bool found = false;
            for (unsigned int s=0; s<(*(hi.first)).second.n; ++s)
            {
              if (vClipped[i] == (*(hi.first)).second.isects[s].p)
              {
                found = true;
                vnfo.idx = (*(hi.first)).second.isects[s].idx;
                break;
              }
            }
            if (!found)
            {
              vnfo.idx = vIdx++;
              numVertices++;
              vInfos.push_back(vnfo);

              (*(hi.first)).second.isects[(*(hi.first)).second.n].p = vClipped[i];
              (*(hi.first)).second.isects[(*(hi.first)).second.n].idx = vnfo.idx;
              (*(hi.first)).second.n++;
            }
          }
          else if ((vnfo.fU + vnfo.fV) >= ((ScalarType)(1.0 - 1e-5)))
          {
            std::pair<EdgeMap_i, bool> mi = edges.insert(std::make_pair(vmin[2], emptyMap));
            std::pair<UIntHMap_i, bool> hi = (*(mi.first)).second.insert(std::make_pair(vmax[2], emptyIsects));
            bool found = false;
            for (unsigned int s=0; s<(*(hi.first)).second.n; ++s)
            {
              if (vClipped[i] == (*(hi.first)).second.isects[s].p)
              {
                found = true;
                vnfo.idx = (*(hi.first)).second.isects[s].idx;
                break;
              }
            }
            if (!found)
            {
              vnfo.idx = vIdx++;
              numVertices++;
              vInfos.push_back(vnfo);

              (*(hi.first)).second.isects[(*(hi.first)).second.n].p = vClipped[i];
              (*(hi.first)).second.isects[(*(hi.first)).second.n].idx = vnfo.idx;
              (*(hi.first)).second.n++;
            }
          }
          else
          {
            vnfo.idx = vIdx++;
            numVertices++;
            vInfos.push_back(vnfo);
          }

          if (i == 0)
          {
            firstV = vnfo.idx;
          }

          if (i > 1)
          {
            tnfo.idx = tIdx++;
            tnfo.v[0] = firstV;
            tnfo.v[1] = lastV;
            tnfo.v[2] = vnfo.idx;

            tInfos.push_back(tnfo);
          }

          lastV = vnfo.idx;
        }
      }
    }

    if (numTriangles == 0)
    {
      return;
    }

    const unsigned int vSize = (unsigned int)(m.vn);
    const unsigned int tSize = (unsigned int)(m.fn);

    typedef Allocator<TriMeshType> TriMeshAllocatorType;

    TriMeshAllocatorType::AddVertices(m, numVertices);
    TriMeshAllocatorType::AddFaces(m, numTriangles);

    unsigned int j = vSize;
    for (size_t i=0; i<vInfos.size(); ++i)
    {
      if (vInfos[i].idx >= vSize)
      {
        const unsigned int tref = vInfos[i].tref;
        vInterp(*(m.face[tref].V(0)), *(m.face[tref].V(1)), *(m.face[tref].V(2)), vInfos[i].fV, vInfos[i].fU, m.vert[j]);
        j++;
      }
    }

    j = tSize;
    for (size_t i=0; i<tInfos.size(); ++i)
    {
      m.face[j].V(0) = &(m.vert[tInfos[i].v[0]]);
      m.face[j].V(1) = &(m.vert[tInfos[i].v[1]]);
      m.face[j].V(2) = &(m.vert[tInfos[i].v[2]]);
      j++;
    }
  }


  /*
    static inline void Box(const Box3<ScalarType> & b, VERTEXINTEPOLATOR & vInterp, const TriMeshType & m, TriMeshType & r);

    Clip mesh "m" against an axis aligned box and put resulting data in mesh "r" (out of place version);

    Notes:
      1) input mesh is not modified;
      2) faces marked as deleted are skipped;
      3) vInterp functor must implement a n operator with signature
             void operator () (const VERTEX & v0, const VERTEX & v1, const VERTEX & v2, const Scalar & a, const Scalar & b, VERTEX & r);
         its semantic is to intepolate vertex attribute across triangle; a typical implementation is;
           r.P() = v0.P() + a * (v1.P() - v0.P()) + b * (v2.P() - v0.P());  // interpolate position
           r.N() = v0.N() + a * (v1.N() - v0.N()) + b * (v2.N() - v0.N());  // interpolate normal
           ...    // interpolate other vertex attributes
  */

  template <typename VERTEXINTEPOLATOR>
  static inline void Box(const Box3<ScalarType> & b, VERTEXINTEPOLATOR & vInterp, const TriMeshType & m, TriMeshType & r)
  {
    r.Clear();

    if (m.fn <= 0)
    {
      return;
    }

    class VertexClipInfo
    {
    public:
      typedef VertexClipInfo ClassType;

      ScalarType fU;
      ScalarType fV;
      unsigned int idx;
      unsigned int tref;
    };

    typedef std::vector<VertexClipInfo> VertexClipInfoVec;

    class TriangleInfo
    {
    public:
      typedef TriangleInfo ClassType;

      unsigned int v[3];
      unsigned int idx;
    };

    typedef std::vector<TriangleInfo> TriangleInfoVec;

    class EdgeIsect
    {
    public:
      CoordType p;
      unsigned int idx;
    };

    class EdgeIntersections
    {
    public:
      unsigned int n;
      EdgeIsect isects[6];

      EdgeIntersections(void)
      {
        this->n = 0;
      }
    };

    typedef std::unordered_map<unsigned int, EdgeIntersections> UIntHMap;
    typedef typename UIntHMap::iterator UIntHMap_i;
    typedef typename UIntHMap::value_type UIntHMap_v;

    typedef std::unordered_map<unsigned int, UIntHMap> EdgeMap;
    typedef typename EdgeMap::iterator EdgeMap_i;
    typedef typename EdgeMap::value_type EdgeMap_v;

    typedef std::unordered_map<unsigned int, unsigned int> UIHMap;
    typedef typename UIHMap::iterator UIHMap_i;

    typedef typename TriMeshType::ConstFaceIterator ConstFaceIterator;

    UIHMap origVertsMap;
    EdgeMap edges;
    VertexClipInfoVec vInfos;
    TriangleInfoVec tInfos;

    CoordType vTriangle[4];
    CoordType vClipped[64];

    CoordType pvP0[64];
    CoordType pvP1[64];

    unsigned int numDeletedTris = 0;
    unsigned int numTriangles = 0;
    unsigned int numVertices = 0;

    unsigned int vIdx = 0;
    unsigned int tIdx = 0;

    ScalarType boxOffsets[6];

    boxOffsets[0] =  b.min[0];
    boxOffsets[1] = -b.max[0];
    boxOffsets[2] =  b.min[1];
    boxOffsets[3] = -b.max[1];
    boxOffsets[4] =  b.min[2];
    boxOffsets[5] = -b.max[2];

    UIntHMap emptyMap;
    EdgeIntersections emptyIsects;

    const ScalarType eps = (ScalarType)(1e-6);

    for (ConstFaceIterator it=m.face.begin(); it!=m.face.end(); ++it)
    {
      if ((*it).IsD())
      {
        continue;
      }

      unsigned int cc[3];

      cc[0] = ClassType::BoxClipCode(boxOffsets, (*it).V(0)->P());
      cc[1] = ClassType::BoxClipCode(boxOffsets, (*it).V(1)->P());
      cc[2] = ClassType::BoxClipCode(boxOffsets, (*it).V(2)->P());

      if ((cc[0] | cc[1] | cc[2]) == 0)
      {
        TriangleInfo tnfo;
        VertexClipInfo vnfo;

        tnfo.idx = tIdx++;

        for (int i=0; i<3; ++i)
        {
          const unsigned int v = (*it).V(i) - &(*(m.vert.begin()));
          std::pair<UIHMap_i, bool> hi = origVertsMap.insert(std::make_pair(v, vIdx));

          if (hi.second)
          {
            vnfo.idx = v;
            vInfos.push_back(vnfo);
            tnfo.v[i] = vIdx++;
          }
          else
          {
            tnfo.v[i] = (*(hi.first)).second;
          }
        }

        tInfos.push_back(tnfo);

        continue;
      }

      if ((cc[0] & cc[1] & cc[2]) != 0)
      {
        numDeletedTris++;
        continue;
      }

      vTriangle[0] = (*it).V(0)->P();
      vTriangle[1] = (*it).V(1)->P();
      vTriangle[2] = (*it).V(2)->P();
      vTriangle[3] = (*it).V(0)->P();

      unsigned int n, n0, n1;

      ClipPolygonLine(0, b.min[0], vTriangle,  4, pvP1,     n1);
      ClipPolygonLine(1, b.max[0], pvP1,      n1, pvP0,     n0);

      ClipPolygonLine(2, b.min[1], pvP0,      n0, pvP1,     n1);
      ClipPolygonLine(3, b.max[1], pvP1,      n1, pvP0,     n0);

      ClipPolygonLine(4, b.min[2], pvP0,      n0, pvP1,     n1);
      ClipPolygonLine(5, b.max[2], pvP1,      n1, vClipped,  n);

      assert(n < 64);

      unsigned int firstV, lastV;


      if (n > 2)
      {
        if (vClipped[0] == vClipped[n - 1])
        {
          n--;
        }

        const CoordType vU = vTriangle[1] - vTriangle[0];
        const CoordType vV = vTriangle[2] - vTriangle[0];

        const ScalarType tArea = (vU ^ vV).SquaredNorm();
        if (tArea < eps)
        {
          continue;
        }

        unsigned int tvidx[3];
        tvidx[0] = (*it).V(0) - &(*(m.vert.begin()));
        tvidx[1] = (*it).V(1) - &(*(m.vert.begin()));
        tvidx[2] = (*it).V(2) - &(*(m.vert.begin()));

        unsigned int refT = (unsigned int)(std::distance(m.face.begin(), it));

        numTriangles += n - 2;

        VertexClipInfo vnfo;
        TriangleInfo tnfo;

        unsigned int vmin[3];
        unsigned int vmax[3];

        if (tvidx[0] < tvidx[1])
        {
          vmin[0] = tvidx[0];
          vmax[0] = tvidx[1];
        }
        else
        {
          vmin[0] = tvidx[1];
          vmax[0] = tvidx[0];
        }

        if (tvidx[0] < tvidx[2])
        {
          vmin[1] = tvidx[0];
          vmax[1] = tvidx[2];
        }
        else
        {
          vmin[1] = tvidx[2];
          vmax[1] = tvidx[0];
        }

        if (tvidx[1] < tvidx[2])
        {
          vmin[2] = tvidx[1];
          vmax[2] = tvidx[2];
        }
        else
        {
          vmin[2] = tvidx[2];
          vmax[2] = tvidx[1];
        }

        for (unsigned int i=0; i<n; ++i)
        {
          vnfo.tref = refT;

          const CoordType vP = vClipped[i] - vTriangle[0];

          ScalarType tAreaU = (vU ^ vP).SquaredNorm();
          ScalarType tAreaV = (vP ^ vV).SquaredNorm();

          vnfo.fU = (ScalarType)(sqrt(tAreaU / tArea));
          vnfo.fV = (ScalarType)(sqrt(tAreaV / tArea));

          unsigned int currVIdx;

          if (vClipped[i] == vTriangle[0])
          {
            std::pair<UIHMap_i, bool> hi = origVertsMap.insert(std::make_pair(tvidx[0], vIdx));
            if (hi.second)
            {
              vnfo.idx = tvidx[0];
              vInfos.push_back(vnfo);
              currVIdx = vIdx++;
            }
            else
            {
              currVIdx = (*(hi.first)).second;
            }
          }
          else if (vClipped[i] == vTriangle[1])
          {
            std::pair<UIHMap_i, bool> hi = origVertsMap.insert(std::make_pair(tvidx[1], vIdx));
            if (hi.second)
            {
              vnfo.idx = tvidx[1];
              vInfos.push_back(vnfo);
              currVIdx = vIdx++;
            }
            else
            {
              currVIdx = (*(hi.first)).second;
            }
          }
          else if (vClipped[i] == vTriangle[2])
          {
            std::pair<UIHMap_i, bool> hi = origVertsMap.insert(std::make_pair(tvidx[2], vIdx));
            if (hi.second)
            {
              vnfo.idx = tvidx[2];
              vInfos.push_back(vnfo);
              currVIdx = vIdx++;
            }
            else
            {
              currVIdx = (*(hi.first)).second;
            }
          }
          else if (vnfo.fV < eps)
          {
            std::pair<EdgeMap_i, bool> mi = edges.insert(std::make_pair(vmin[1], emptyMap));
            std::pair<UIntHMap_i, bool> hi = (*(mi.first)).second.insert(std::make_pair(vmax[1], emptyIsects));
            bool found = false;
            for (unsigned int s=0; s<(*(hi.first)).second.n; ++s)
            {
              if (vClipped[i] == (*(hi.first)).second.isects[s].p)
              {
                found = true;
                vnfo.idx = (unsigned int)(-1);
                currVIdx = (*(hi.first)).second.isects[s].idx;
                break;
              }
            }
            if (!found)
            {
              (*(hi.first)).second.isects[(*(hi.first)).second.n].p = vClipped[i];
              (*(hi.first)).second.isects[(*(hi.first)).second.n].idx = vIdx;
              (*(hi.first)).second.n++;

              vnfo.idx = (unsigned int)(-1);
              numVertices++;
              vInfos.push_back(vnfo);
              currVIdx = vIdx++;
            }
          }
          else if (vnfo.fU < eps)
          {
            std::pair<EdgeMap_i, bool> mi = edges.insert(std::make_pair(vmin[0], emptyMap));
            std::pair<UIntHMap_i, bool> hi = (*(mi.first)).second.insert(std::make_pair(vmax[0], emptyIsects));
            bool found = false;
            for (unsigned int s=0; s<(*(hi.first)).second.n; ++s)
            {
              if (vClipped[i] == (*(hi.first)).second.isects[s].p)
              {
                found = true;
                vnfo.idx = (unsigned int)(-1);
                currVIdx = (*(hi.first)).second.isects[s].idx;
                break;
              }
            }
            if (!found)
            {
              (*(hi.first)).second.isects[(*(hi.first)).second.n].p = vClipped[i];
              (*(hi.first)).second.isects[(*(hi.first)).second.n].idx = vIdx;
              (*(hi.first)).second.n++;

              vnfo.idx = (unsigned int)(-1);
              numVertices++;
              vInfos.push_back(vnfo);
              currVIdx = vIdx++;
            }
          }
          else if ((vnfo.fU + vnfo.fV) >= ((ScalarType)(1.0 - 1e-5)))
          {
            std::pair<EdgeMap_i, bool> mi = edges.insert(std::make_pair(vmin[2], emptyMap));
            std::pair<UIntHMap_i, bool> hi = (*(mi.first)).second.insert(std::make_pair(vmax[2], emptyIsects));
            bool found = false;
            for (unsigned int s=0; s<(*(hi.first)).second.n; ++s)
            {
              if (vClipped[i] == (*(hi.first)).second.isects[s].p)
              {
                found = true;
                vnfo.idx = (unsigned int)(-1);
                currVIdx = (*(hi.first)).second.isects[s].idx;
                break;
              }
            }
            if (!found)
            {
              (*(hi.first)).second.isects[(*(hi.first)).second.n].p = vClipped[i];
              (*(hi.first)).second.isects[(*(hi.first)).second.n].idx = vIdx;
              (*(hi.first)).second.n++;

              vnfo.idx = (unsigned int)(-1);
              numVertices++;
              vInfos.push_back(vnfo);
              currVIdx = vIdx++;
            }
          }
          else
          {
            vnfo.idx = (unsigned int)(-1);
            numVertices++;
            vInfos.push_back(vnfo);
            currVIdx = vIdx++;
          }

          if (i == 0)
          {
            firstV = currVIdx;
          }

          if (i > 1)
          {
            tnfo.idx = tIdx++;
            tnfo.v[0] = firstV;
            tnfo.v[1] = lastV;
            tnfo.v[2] = currVIdx;

            tInfos.push_back(tnfo);
          }

          lastV = currVIdx;
        }
      }
    }

    if (tInfos.empty())
    {
      return;
    }

    typedef Allocator<TriMeshType> TriMeshAllocatorType;

    TriMeshAllocatorType::AddVertices(r, (int)(vInfos.size()));
    TriMeshAllocatorType::AddFaces(r, (int)(tInfos.size()));

    for (size_t i=0; i<vInfos.size(); ++i)
    {
      if (vInfos[i].idx != ((unsigned int)(-1)))
      {
        r.vert[i] = m.vert[vInfos[i].idx];
      }
      else
      {
        const unsigned int tref = vInfos[i].tref;
        vInterp(*(m.face[tref].V(0)), *(m.face[tref].V(1)), *(m.face[tref].V(2)), vInfos[i].fV, vInfos[i].fU, r.vert[i]);
      }
    }

    for (size_t i=0; i<tInfos.size(); ++i)
    {
      r.face[i].V(0) = &(r.vert[tInfos[i].v[0]]);
      r.face[i].V(1) = &(r.vert[tInfos[i].v[1]]);
      r.face[i].V(2) = &(r.vert[tInfos[i].v[2]]);
    }
  }

protected:

  static inline unsigned int BoxClipCode(const ScalarType * offsets, const CoordType & p)
  {
    //const ScalarType eps = (ScalarType)(-1e-5);
    const ScalarType eps = (ScalarType)(0);
    unsigned int code = 0;

    code |= ((( p[0] - offsets[0]) < eps) ? (1 << 0) : (0));
    code |= (((-p[0] - offsets[1]) < eps) ? (1 << 1) : (0));
    code |= ((( p[1] - offsets[2]) < eps) ? (1 << 2) : (0));
    code |= (((-p[1] - offsets[3]) < eps) ? (1 << 3) : (0));
    code |= ((( p[2] - offsets[4]) < eps) ? (1 << 4) : (0));
    code |= (((-p[2] - offsets[5]) < eps) ? (1 << 5) : (0));

    return (code);
  }

  static inline unsigned int InRegion(int mode, const ScalarType & value, const CoordType & p_in)
  {
    //const ScalarType eps = (ScalarType)(-1e-5);
    const ScalarType eps = (ScalarType)(0);
    unsigned int flag = 0;

    switch(mode)
    {
      case 0:
        flag = p_in[0] + eps < value;
        break;
      case 1:
        flag = p_in[0] > value + eps;
        break;
      case 2:
        flag = p_in[1] + eps < value;
        break;
      case 3:
        flag = p_in[1] > value + eps;
        break;
      case 4:
        flag = p_in[2] + eps < value;
        break;
      case 5:
        flag = p_in[2] > value + eps;
        break;
      default:
        break;
    }

    return (flag);
  }

  static inline void CrossPoint(int mode, const ScalarType & value, const CoordType & SP, const CoordType & PP, CoordType & p_out)
  {
    switch(mode)
    {
      case 0:
      case 1:
        p_out[0] = value;
        if ((PP[0] - SP[0]) == ((ScalarType)(0)))
        {
          p_out[1] = PP[1];
          p_out[2] = PP[2];
        }
        else
        {
          p_out[1] = SP[1] + (value - SP[0]) * (PP[1] - SP[1]) / (PP[0] - SP[0]);
          p_out[2] = SP[2] + (value - SP[0]) * (PP[2] - SP[2]) / (PP[0] - SP[0]);
        }
        break;
      case 2:
      case 3:
        p_out[1] = value;
        if ((PP[1] - SP[1]) == ((ScalarType)(0)))
        {
          p_out[0] = PP[0];
          p_out[2] = PP[2];
        }
        else
        {
          p_out[0] = SP[0] + (value - SP[1]) * (PP[0] - SP[0]) / (PP[1] - SP[1]);
          p_out[2] = SP[2] + (value - SP[1]) * (PP[2] - SP[2]) / (PP[1] - SP[1]);
        }
        break;
      case 4:
      case 5:
        p_out[2] = value;
        if ((PP[2] - SP[2]) == ((ScalarType)(0)))
        {
          p_out[0] = PP[0];
          p_out[1] = PP[1];
        }
        else
        {
          p_out[0] = SP[0] + (value - SP[2]) * (PP[0] - SP[0]) / (PP[2] - SP[2]);
          p_out[1] = SP[1] + (value - SP[2]) * (PP[1] - SP[1]) / (PP[2] - SP[2]);
        }
        break;
      default:
        break;
    }
  }

  static inline void ClipPolygonLine(int mode, const ScalarType & value, CoordType * P_in, unsigned int n_in, CoordType * P_out, unsigned int & n_out)
  {
    unsigned int ps;
    CoordType * SP;
    CoordType * PP;

    n_out = 0;
    SP = &P_in[n_in-1];

    if (ClassType::InRegion(mode, value, *SP))
    {
      ps = 0;
    }
    else
    {
      ps = 2;
    }

    for(unsigned int i=0; i<n_in; ++i)
    {
      PP = &(P_in[i]);
      ps = (ps >> 1) | ((ClassType::InRegion(mode, value, *PP)) ? (0) : (2));

      switch(ps)
      {
        case 0:
          break;
        case 1:
          ClassType::CrossPoint(mode, value, *SP, *PP, P_out[n_out]);
          n_out++;
          break;
        case 2:
          ClassType::CrossPoint(mode, value, *SP, *PP, P_out[n_out]);
          n_out++;
          P_out[n_out] = *PP;
          n_out++;
          break;
        case 3:
          P_out[n_out] = *PP;
          n_out++;
          break;
        default:
          break;
      }

      SP = PP;
    }
  }

};

} // end namespace tri
} // end namespace vcg

#endif // __VCGLIB_TRI_CLIP