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// This file is part of libigl, a simple c++ geometry processing library.
//
// Copyright (C) 2019 Hanxiao Shen <hanxiao@cs.nyu.edu>
//
// 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_PREDICATES_EAR_CLIPPING_H
#define IGL_PREDICATES_EAR_CLIPPING_H
#include <Eigen/Core>
#include "../igl_inline.h"
namespace igl
{
namespace predicates
{
/// Implementation of ear clipping triangulation algorithm for a 2D polygon.
/// https://www.geometrictools.com/Documentation/TriangulationByEarClipping.pdf
/// If the polygon is simple and oriented counter-clockwise, all vertices
/// will be clipped and the result mesh is (P,eF) Otherwise, the function
/// will try to clip as many ears as possible.
///
/// @param[in] P : n*2, size n 2D polygon
/// @param[in] RT: n*1, preserved vertices (do not clip) marked as 1, otherwise 0
/// @param[out] eF: clipped ears, in original index of P
/// @param[out] I : size #nP vector, maps index from nP to P, e.g. nP's ith vertex is origianlly I(i) in P
///
/// \pre To result in a proper mesh, P should be oriented counter-clockwise
/// with no self-intersections.
///
/// \note This implementation does not handle polygons with holes.
///
/// \bug https://github.com/libigl/libigl/issues/1563
template <
typename DerivedP,
typename DerivedRT,
typename DerivedF,
typename DerivedI>
IGL_INLINE void ear_clipping(
const Eigen::MatrixBase<DerivedP>& P,
const Eigen::MatrixBase<DerivedRT>& RT,
Eigen::PlainObjectBase<DerivedF>& eF,
Eigen::PlainObjectBase<DerivedI>& I);
/// \overload
/// \brief Reverses P if necessary. Orientation of output will match input
/// \return true if mesh is proper (should correspond to input being a
/// simple polygon in either orientation), false otherwise.
template <typename DerivedP, typename DerivedF>
IGL_INLINE bool ear_clipping(
const Eigen::MatrixBase<DerivedP>& P,
Eigen::PlainObjectBase<DerivedF>& eF);
}
}
#ifndef IGL_STATIC_LIBRARY
# include "ear_clipping.cpp"
#endif
#endif