MEdge.h

// Gmsh - Copyright (C) 1997-2018 C. Geuzaine, J.-F. Remacle
//
// See the LICENSE.txt file for license information. Please report all
// bugs and problems to the public mailing list <gmsh@onelab.info>.

#ifndef _MEDGE_H_
#define _MEDGE_H_

#include <functional>
#include "MVertex.h"
#include "SVector3.h"

// A mesh edge.
class MEdge {
 private:
  MVertex *_v[2];
  char _si[2]; // sorted indices

 public:
  MEdge()
  {
    _v[0] = _v[1] = 0;
    _si[0] = _si[1] = 0;
  }
  MEdge(MVertex *v0, MVertex *v1)
  {
    _v[0] = v0; _v[1] = v1;
    if(_v[1]->getNum() < _v[0]->getNum()) {
      _si[0] = 1;
      _si[1] = 0;
    }
    else {
      _si[0] = 0;
      _si[1] = 1;
    }
  }
  inline int getNumVertices() const { return 2; }
  inline MVertex *getVertex(const int i) const { return _v[i]; }
  inline MVertex *getSortedVertex(const int i) const { return _v[int(_si[i])]; }
  inline MVertex *getMinVertex() const { return _v[int(_si[0])]; }
  inline MVertex *getMaxVertex() const { return _v[int(_si[1])]; }
  
  inline int computeCorrespondence(MEdge& other) {
    if (other.getVertex(0) == _v[0] && other.getVertex(1) == _v[1]) return 1;
    else if (other.getVertex(0) == _v[1] && other.getVertex(1) == _v[0]) return -1;
    return 0;
  }

  SVector3 scaledTangent() const
  {
    return SVector3(_v[1]->x() - _v[0]->x(),
                    _v[1]->y() - _v[0]->y(),
                    _v[1]->z() - _v[0]->z());
  }
  SVector3 tangent() const
  {
    SVector3 t(_v[1]->x() - _v[0]->x(),
               _v[1]->y() - _v[0]->y(),
               _v[1]->z() - _v[0]->z());
    t.normalize();
    return t;
  }
  double length() const
  {
    SVector3 t(_v[1]->x() - _v[0]->x(),
               _v[1]->y() - _v[0]->y(),
               _v[1]->z() - _v[0]->z());
    return t.norm();
  }
  SVector3 normal() const