// This file is part of libigl, a simple c++ geometry processing library.
// 
// Copyright (C) 2015 Qingnan 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_COPYLEFT_CGAL_OUTER_FACET_H
#define IGL_COPYLEFT_CGAL_OUTER_FACET_H
#include "../../igl_inline.h"
#include <Eigen/Core>

namespace igl
{
  namespace copyleft
  {
    namespace cgal
    {
        // Find a facet that is reachable from infinity without crossing any faces.
        // Such facet is called "outer facet."
        //
        // Precondition: The input mesh must have all self-intersection resolved.  I.e
        // there is no duplicated vertices, no overlapping edge and no intersecting
        // faces (the only exception is there could be topologically duplicated faces).
        // See cgal::remesh_self_intersections.h for how to obtain such input.
        //
        // This function differ from igl::outer_facet() in the fact this
        // function is more robust because it does not rely on facet normals.
        //
        // Inputs:
        //   V  #V by 3 list of vertex positions
        //   F  #F by 3 list of triangle indices into V
        //   I  #I list of facets to consider
        // Outputs:
        //   f  Index of the outer facet.
        //   flipped  true iff the normal of f points inwards.
        template<
            typename DerivedV,
            typename DerivedF,
            typename DerivedI,
            typename IndexType
            >
        IGL_INLINE void outer_facet(
                const Eigen::PlainObjectBase<DerivedV> & V,
                const Eigen::PlainObjectBase<DerivedF> & F,
                const Eigen::PlainObjectBase<DerivedI> & I,
                IndexType & f,
                bool & flipped);

      // Find a facet that is reachable from infinity without crossing any faces.
      // Such facet is called "outer facet."
      //
      // Precondition: The input mesh must have all self-intersection resolved.
      // I.e there is no duplicated vertices, no overlapping edge and no
      // intersecting faces (the only exception is there could be topologically
      // duplicated faces).  See cgal::remesh_self_intersections.h for how to
      // obtain such input.
      //
      // Inputs:
      //   V  #V by 3 list of vertex positions
      //   F  #F by 3 list of triangle indices into V
      //   N  #N by 3 list of face normals
      //   I  #I list of facets to consider
      // Outputs:
      //   f  Index of the outer facet.
      //   flipped  true iff the normal of f points inwards.
      template<
          typename DerivedV,
          typename DerivedF,
          typename DerivedN,
          typename DerivedI,
          typename IndexType
          >
      IGL_INLINE void outer_facet(
              const Eigen::PlainObjectBase<DerivedV> & V,
              const Eigen::PlainObjectBase<DerivedF> & F,
              const Eigen::PlainObjectBase<DerivedN> & N,
              const Eigen::PlainObjectBase<DerivedI> & I,
              IndexType & f,
              bool & flipped);

    }

  }
}

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