107 lines
2.6 KiB
C++
107 lines
2.6 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 "exterior_edges.h"
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#include "oriented_facets.h"
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#include "sort.h"
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#include "unique_rows.h"
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#include <cassert>
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#include <unordered_map>
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#include <utility>
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#include <iostream>
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//template <typename T> inline int sgn(T val) {
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// return (T(0) < val) - (val < T(0));
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//}
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//static void mod2(std::pair<const std::pair<const int, const int>, int>& p)
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//{
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// using namespace std;
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// // Be sure that sign of mod matches sign of argument
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// p.second = p.second%2 ? sgn(p.second) : 0;
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//}
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//// http://stackoverflow.com/a/5517869/148668
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//struct Compare
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//{
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// int i;
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// Compare(const int& i) : i(i) {}
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//};
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//bool operator==(const std::pair<std::pair<const int, const int>,int>&p, const Compare& c)
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//{
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// return c.i == p.second;
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//}
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//bool operator==(const Compare& c, const std::pair<std::pair<const int, const int>, int> &p)
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//{
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// return c.i == p.second;
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//}
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IGL_INLINE void igl::exterior_edges(
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const Eigen::MatrixXi & F,
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Eigen::MatrixXi & E)
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{
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using namespace Eigen;
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using namespace std;
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assert(F.cols() == 3);
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const size_t m = F.rows();
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MatrixXi all_E,sall_E,sort_order;
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// Sort each edge by index
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oriented_facets(F,all_E);
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sort(all_E,2,true,sall_E,sort_order);
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// Find unique edges
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MatrixXi uE;
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VectorXi IA,EMAP;
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unique_rows(sall_E,uE,IA,EMAP);
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VectorXi counts = VectorXi::Zero(uE.rows());
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for(size_t a = 0;a<3*m;a++)
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{
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counts(EMAP(a)) += (sort_order(a)==0?1:-1);
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}
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E.resize(all_E.rows(),2);
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{
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int e = 0;
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const size_t nue = uE.rows();
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// Append each unique edge with a non-zero amount of signed occurrences
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for(size_t ue = 0; ue<nue; ue++)
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{
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const int count = counts(ue);
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size_t i,j;
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if(count == 0)
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{
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continue;
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}else if(count < 0)
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{
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i = uE(ue,1);
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j = uE(ue,0);
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}else if(count > 0)
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{
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i = uE(ue,0);
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j = uE(ue,1);
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}
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// Append edge for every repeated entry
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const int abs_count = abs(count);
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for(int k = 0;k<abs_count;k++)
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{
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E(e,0) = i;
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E(e,1) = j;
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e++;
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}
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}
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E.conservativeResize(e,2);
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}
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}
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IGL_INLINE Eigen::MatrixXi igl::exterior_edges( const Eigen::MatrixXi & F)
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{
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using namespace Eigen;
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MatrixXi E;
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exterior_edges(F,E);
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return E;
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}
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