mev.cpp

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/**
 *\file         mev.cpp
 *
 *\brief        subdivide edge cycle at a vertex.
 *
 *              make edge and vertex: subdivision the cycle of half edges emanating from a vertex; return the new half edge tailed at new vertex.
 *              the pair of half edges is either inserted as 2 consecutive half edges in a loop, or inserted separately into two loops of two faces.
 *
 *\image        html mev.jpg
 *
 *\author       Xianming Chen\n
 *              Computer Science Department\n
 *              University of Utah
 *
 *\date          16 Aug 2006\n
 *              Copyright (c) 2006, University of Utah
 */


#include "euler.h"
#include <cassert>
#include <utility>
using namespace std;


namespace euler
{
  /**
   * subdivide edge cycle (at p0=p1==p2) into 
   *   p0p+[e2, e1) at p0 (change in plance), and 
   *   pp0+[e1, e2) at p (as new edge cycle of new vertex).
   */
  edge_t* solid_t :: mev(edge_t* e1, edge_t* e2, point_t const& p)
  { 
    assert(e1->v == e2->v); 
    return mev(e1, e2, e1->l->f->s->new_vertex(p)); 
  }


  edge_t* solid_t :: mev(edge_t* e1, edge_t* e2, vertex_t* v)
  {
    pair<edge_t*, edge_t*> pr = 
      add_edge_pair(e1->v, e1,  
                    v, e2);

    // subdivide edge cycle by setting vertex of [e1, e2) to p.
    for(edge_t *&ne2 = pr.second, *e = pr.first->nxt; e != ne2; e = e->o->nxt)
    {
      e->v = ne2->v;
    }
    solid_t::assert_consistent_B_rep();
    return pr.second;
  }

  edge_t* loop_t :: mev(edge_t* e, point_t const& p)
  { 
    return f->s->mev(e, e, p);
  }  

  edge_t* loop_t :: mev(edge_t* e, vertex_t* v)              
  { 
    return f->s->mev(e, e, v);
  }  



}//end namespace euler

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