// This file is part of libigl, a simple c++ geometry processing library.
// 
// Copyright (C) 2016 Qingan Zhou <qnzhou@gmail.com>
// 
// This Source Code Form is subject to the terms of the Mozilla Public License 
// v. 2.0. If a copy of the MPL was not distributed with this file, You can 
// obtain one at http://mozilla.org/MPL/2.0/.

#ifndef IGL_FLIP_EDGE_H
#define IGL_FLIP_EDGE_H

#include "igl_inline.h"
#include <Eigen/Core>
#include <vector>

namespace igl
{
  // Flip an edge in a triangle mesh.  The edge specified by uei must have
  // exactly **two** adjacent faces.  Violation will result in exception.
  // Another warning: edge flipping could convert manifold mesh into
  // non-manifold.
  //
  // Inputs:
  //   F    #F by 3 list of triangles.
  //   E    #F*3 by 2 list of all of directed edges
  //   uE   #uE by 2 list of unique undirected edges
  //   EMAP #F*3 list of indices into uE, mapping each directed edge to unique
  //        undirected edge
  //   uE2E #uE list of lists of indices into E of coexisting edges
  //   ue   index into uE the edge to be flipped.
  //
  // Output:
  //   Updated F, E, uE, EMAP and uE2E.
  template <
    typename DerivedF,
    typename DerivedE,
    typename DeriveduE,
    typename DerivedEMAP,
    typename uE2EType>
  IGL_INLINE void flip_edge(
    Eigen::PlainObjectBase<DerivedF> & F,
    Eigen::PlainObjectBase<DerivedE> & E,
    Eigen::PlainObjectBase<DeriveduE> & uE,
    Eigen::PlainObjectBase<DerivedEMAP> & EMAP,
    std::vector<std::vector<uE2EType> > & uE2E,
    const size_t uei);
}

#ifndef IGL_STATIC_LIBRARY
#  include "flip_edge.cpp"
#endif
#endif