72 lines
3.2 KiB
C++
72 lines
3.2 KiB
C++
// This file is part of libigl, a simple c++ geometry processing library.
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//
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// Copyright (C) 2016 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 <igl/dijkstra.h>
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template <typename IndexType, typename DerivedD, typename DerivedP>
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IGL_INLINE int igl::dijkstra_compute_paths(const IndexType &source,
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const std::set<IndexType> &targets,
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const std::vector<std::vector<IndexType> >& VV,
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Eigen::PlainObjectBase<DerivedD> &min_distance,
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Eigen::PlainObjectBase<DerivedP> &previous)
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{
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int numV = VV.size();
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min_distance.setConstant(numV, 1, std::numeric_limits<typename DerivedD::Scalar>::infinity());
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min_distance[source] = 0;
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previous.setConstant(numV, 1, -1);
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std::set<std::pair<typename DerivedD::Scalar, IndexType> > vertex_queue;
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vertex_queue.insert(std::make_pair(min_distance[source], source));
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while (!vertex_queue.empty())
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{
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typename DerivedD::Scalar dist = vertex_queue.begin()->first;
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IndexType u = vertex_queue.begin()->second;
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vertex_queue.erase(vertex_queue.begin());
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if (targets.find(u)!= targets.end())
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return u;
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// Visit each edge exiting u
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const std::vector<int> &neighbors = VV[u];
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for (std::vector<int>::const_iterator neighbor_iter = neighbors.begin();
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neighbor_iter != neighbors.end();
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neighbor_iter++)
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{
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IndexType v = *neighbor_iter;
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typename DerivedD::Scalar distance_through_u = dist + 1.;
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if (distance_through_u < min_distance[v]) {
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vertex_queue.erase(std::make_pair(min_distance[v], v));
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min_distance[v] = distance_through_u;
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previous[v] = u;
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vertex_queue.insert(std::make_pair(min_distance[v], v));
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}
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}
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}
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//we should never get here
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return -1;
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}
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template <typename IndexType, typename DerivedP>
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IGL_INLINE void igl::dijkstra_get_shortest_path_to(const IndexType &vertex,
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const Eigen::PlainObjectBase<DerivedP> &previous,
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std::vector<IndexType> &path)
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{
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IndexType source = vertex;
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path.clear();
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for ( ; source != -1; source = previous[source])
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path.push_back(source);
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}
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#ifdef IGL_STATIC_LIBRARY
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// Explicit template instantiation
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template int igl::dijkstra_compute_paths<int, Eigen::Matrix<double, -1, 1, 0, -1, 1>, Eigen::Matrix<int, -1, 1, 0, -1, 1> >(int const&, std::set<int, std::less<int>, std::allocator<int> > const&, std::vector<std::vector<int, std::allocator<int> >, std::allocator<std::vector<int, std::allocator<int> > > > const&, Eigen::PlainObjectBase<Eigen::Matrix<double, -1, 1, 0, -1, 1> >&, Eigen::PlainObjectBase<Eigen::Matrix<int, -1, 1, 0, -1, 1> >&);
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template void igl::dijkstra_get_shortest_path_to<int, Eigen::Matrix<int, -1, 1, 0, -1, 1> >(int const&, Eigen::PlainObjectBase<Eigen::Matrix<int, -1, 1, 0, -1, 1> > const&, std::vector<int, std::allocator<int> >&);
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#endif
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