87 lines
2.4 KiB
C++
87 lines
2.4 KiB
C++
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// This file is part of libigl, a simple c++ geometry processing library.
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//
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// Copyright (C) 2015 Alec Jacobson <alecjacobson@gmail.com>
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//
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// This Source Code Form is subject to the terms of the Mozilla Public License
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// v. 2.0. If a copy of the MPL was not distributed with this file, You can
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// obtain one at http://mozilla.org/MPL/2.0/.
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#include "edge_collapse_is_valid.h"
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#include "collapse_edge.h"
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#include "circulation.h"
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#include "intersect.h"
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#include "unique.h"
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#include "list_to_matrix.h"
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#include <vector>
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IGL_INLINE bool igl::edge_collapse_is_valid(
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const int e,
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const Eigen::MatrixXi & F,
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const Eigen::MatrixXi & E,
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const Eigen::VectorXi & EMAP,
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const Eigen::MatrixXi & EF,
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const Eigen::MatrixXi & EI)
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{
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using namespace Eigen;
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using namespace std;
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// For consistency with collapse_edge.cpp, let's determine edge flipness
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// (though not needed to check validity)
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const int eflip = E(e,0)>E(e,1);
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// source and destination
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const int s = eflip?E(e,1):E(e,0);
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const int d = eflip?E(e,0):E(e,1);
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if(s == IGL_COLLAPSE_EDGE_NULL && d==IGL_COLLAPSE_EDGE_NULL)
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{
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return false;
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}
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// check if edge collapse is valid: intersection of vertex neighbors of s and
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// d should be exactly 2+(s,d) = 4
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// http://stackoverflow.com/a/27049418/148668
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{
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// all vertex neighbors around edge, including the two vertices of the edge
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const auto neighbors = [](
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const int e,
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const bool ccw,
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const Eigen::MatrixXi & F,
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const Eigen::MatrixXi & E,
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const Eigen::VectorXi & EMAP,
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const Eigen::MatrixXi & EF,
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const Eigen::MatrixXi & EI)
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{
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vector<int> N,uN;
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vector<int> V2Fe = circulation(e, ccw,EMAP,EF,EI);
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for(auto f : V2Fe)
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{
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N.push_back(F(f,0));
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N.push_back(F(f,1));
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N.push_back(F(f,2));
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}
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vector<size_t> _1,_2;
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igl::unique(N,uN,_1,_2);
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VectorXi uNm;
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list_to_matrix(uN,uNm);
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return uNm;
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};
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VectorXi Ns = neighbors(e, eflip,F,E,EMAP,EF,EI);
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VectorXi Nd = neighbors(e,!eflip,F,E,EMAP,EF,EI);
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VectorXi Nint = igl::intersect(Ns,Nd);
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if(Nint.size() != 4)
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{
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return false;
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}
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if(Ns.size() == 4 && Nd.size() == 4)
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{
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VectorXi NsNd(8);
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NsNd<<Ns,Nd;
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VectorXi Nun,_1,_2;
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igl::unique(NsNd,Nun,_1,_2);
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// single tet, don't collapse
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if(Nun.size() == 4)
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{
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return false;
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}
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}
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}
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return true;
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}
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