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// This file is part of libigl, a simple c++ geometry processing library.
//
// Copyright (C) 2015 Alec Jacobson <alecjacobson@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_EDGE_COLLAPSE_IS_VALID_H
#define IGL_EDGE_COLLAPSE_IS_VALID_H
#include "igl_inline.h"
#include <Eigen/Core>
#include <vector>
namespace igl
{
// Assumes (V,F) is a closed manifold mesh (except for previouslly collapsed
// faces which should be set to:
// [IGL_COLLAPSE_EDGE_NULL IGL_COLLAPSE_EDGE_NULL IGL_COLLAPSE_EDGE_NULL].
// Tests whether collapsing exactly two faces and exactly 3 edges from E (e
// and one side of each face gets collapsed to the other) will result in a
// mesh with the same topology.
//
// Inputs:
// e index into E of edge to try to collapse. E(e,:) = [s d] or [d s] so
// that s<d, then d is collapsed to s.
// F #F by 3 list of face indices into V.
// E #E by 2 list of edge indices into V.
// EMAP #F*3 list of indices into E, mapping each directed edge to unique
// unique edge in E
// EF #E by 2 list of edge flaps, EF(e,0)=f means e=(i-->j) is the edge of
// F(f,:) opposite the vth corner, where EI(e,0)=v. Similarly EF(e,1) "
// e=(j->i)
// EI #E by 2 list of edge flap corners (see above).
// Returns true if edge collapse is valid
IGL_INLINE bool edge_collapse_is_valid(
const int e,
const Eigen::MatrixXi & F,
const Eigen::MatrixXi & E,
const Eigen::VectorXi & EMAP,
const Eigen::MatrixXi & EF,
const Eigen::MatrixXi & EI);
// Inputs:
// Nsv #Nsv list of "next" vertices circulating around starting vertex of
// edge
// Ndv #Ndv list of "next" vertices circulating around destination vertex of
// edge
// Outputs:
// Nsv (side-effect: sorted by value)
// Ndv (side-effect: sorted by value)
// Returns true iff edge collapse is valid
//
// See also: circulation
IGL_INLINE bool edge_collapse_is_valid(
/*const*/ std::vector<int> & Nsv,
/*const*/ std::vector<int> & Ndv);
}
#ifndef IGL_STATIC_LIBRARY
# include "edge_collapse_is_valid.cpp"
#endif
#endif