face.cpp

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/*:
**     face.cpp - face
**
**  Copyright (C) 2004 Luiz Velho, Hélio Lopes, Esdras Medeiros.
*/

#include "mesh.h"

/* indices of 3-ring and n-ring */
#define NEXT3(k)        ((k < 2)? (k+1) : 0) 
#define PREV3(k)        ((k > 0)? (k-1) : 2) 


using namespace Mesh;
Face::Face(Surf* s, Hedge *e0, Hedge *e1, Hedge *e2)
{
  s_ = s;
  reuse(e0, e1, e2);
}
Face* Face::reuse(Hedge *e0, Hedge *e1, Hedge *e2)
{
  e_ = e0;
  e0->set_next(e1); e1->set_next(e2); e2->set_next(e0);
  e0->set_face(this); e1->set_face(this); e2->set_face(this);
  return this;
}
int  Face::reuse(Hedge *e, Hedge *ne)
{
  Hedge *e0, *e1, *e2;
  e0 = e_;
  e1 = e_->next();
  e2 = e_->next()->next();
  
  if (e0 == e){
    reuse(ne, e1, e2);
    return 0;
  }
  if (e1 == e){
    reuse(e0, ne, e2); 
    return 1;
  }
  if (e2 == e){
    reuse(e0, e1, ne);
    return 2;
  }

  return -1;
}

Hedge* Face::hedge(int k)
{
  switch (k) {
  case 0: return e_;
  case 1: return e_->next();
  case 2: return e_->next()->next();
  }
  throw Error("hedge index");
}
Vertex* Face::vertex(int k)
{
  return hedge(PREV3(k))->org();
}
void  Face::set_hedge(int k, Hedge* h)
{
  Hedge *n = hedge(NEXT3(k));
  Hedge *p = hedge(PREV3(k));
  h->set_next(n);
  p->set_next(h);
  if (k == 0) e_ = h;
}
void Face::link_edges()
{
  for (int k = 0; k < 3; k++)
    hedge(k)->set_face(this);
}

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