// This file is part of libigl, a simple c++ geometry processing library.
//
// Copyright (C) 2014 Daniele Panozzo <daniele.panozzo@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_VERTEX_TRIANGLE_ADJACENCY_H
#define IGL_VERTEX_TRIANGLE_ADJACENCY_H
#include <igl/igl_inline.h>

#include <Eigen/Dense>
#include <vector>

namespace igl
{
  // vertex_face_adjacency constructs the vertex-face topology of a given mesh (V,F)
  //
  // Inputs:
  //   //V  #V by 3 list of vertex coordinates
  //   n  number of vertices #V (e.g. `F.maxCoeff()+1` or `V.rows()`)
  //   F  #F by dim list of mesh faces (must be triangles)
  // Outputs:
  //   VF  #V list of lists of incident faces (adjacency list)
  //   VI  #V list of lists of index of incidence within incident faces listed
  //     in VF
  //
  // See also: edges, cotmatrix, diag, vv
  //
  // Known bugs: this should not take V as an input parameter.
  // Known bugs/features: if a facet is combinatorially degenerate then faces
  // will appear multiple times in VF and correpondingly in VFI (j appears
  // twice in F.row(i) then i will appear twice in VF[j])
  template <typename DerivedF, typename VFType, typename VFiType>
  IGL_INLINE void vertex_triangle_adjacency(
    const typename DerivedF::Scalar n,
    const Eigen::PlainObjectBase<DerivedF>& F,
    std::vector<std::vector<VFType> >& VF,
    std::vector<std::vector<VFiType> >& VFi);
  template <typename DerivedV, typename DerivedF, typename IndexType>
  IGL_INLINE void vertex_triangle_adjacency(
    const Eigen::PlainObjectBase<DerivedV>& V,
    const Eigen::PlainObjectBase<DerivedF>& F,
    std::vector<std::vector<IndexType> >& VF,
    std::vector<std::vector<IndexType> >& VFi);
}

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

#endif