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Diffstat (limited to 'GudhUI/utils/Edge_collapsor.h')
-rw-r--r-- | GudhUI/utils/Edge_collapsor.h | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/GudhUI/utils/Edge_collapsor.h b/GudhUI/utils/Edge_collapsor.h new file mode 100644 index 00000000..151e9b01 --- /dev/null +++ b/GudhUI/utils/Edge_collapsor.h @@ -0,0 +1,97 @@ +/* This file is part of the Gudhi Library. The Gudhi library + * (Geometric Understanding in Higher Dimensions) is a generic C++ + * library for computational topology. + * + * Author(s): David Salinas + * + * Copyright (C) 2014 INRIA Sophia Antipolis-Mediterranee (France) + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + * + */ + +#ifndef UTILS_EDGE_COLLAPSOR_H_ +#define UTILS_EDGE_COLLAPSOR_H_ + +#include <list> +#include "utils/Edge_contractor.h" +#include "utils/UI_utils.h" + +/** + * Iteratively puts every vertex at the center of its neighbors + */ +template<typename SkBlComplex> class Edge_collapsor { + private: + SkBlComplex& complex_; + unsigned num_collapses_; + + public: + typedef typename SkBlComplex::Vertex_handle Vertex_handle; + typedef typename SkBlComplex::Edge_handle Edge_handle; + + /** + * @brief Collapse num_collapses edges. If num_collapses<0 then it collapses all possible edges. + * Largest edges are collapsed first. + * + */ + Edge_collapsor(SkBlComplex& complex, unsigned num_collapses) : + complex_(complex), num_collapses_(num_collapses) { + std::list<Edge_handle> edges; + edges.insert(edges.begin(), complex_.edge_range().begin(), complex_.edge_range().end()); + + edges.sort( + [&](Edge_handle e1, Edge_handle e2) { + return squared_edge_length(e1) < squared_edge_length(e2); + }); + + collapse_edges(edges); + } + + private: + void collapse_edges(std::list<Edge_handle>& edges) { + while (!edges.empty() && num_collapses_--) { + Edge_handle current_edge = edges.front(); + edges.pop_front(); + if (is_link_reducible(current_edge)) + complex_.remove_edge(current_edge); + } + } + + bool is_link_reducible(Edge_handle e) { + auto link = complex_.link(e); + + if (link.empty()) + return false; + + if (link.is_cone()) + return true; + + if (link.num_connected_components() > 1) + return false; + + Edge_contractor<SkBlComplex> contractor(link, link.num_vertices() - 1); + + return (link.num_vertices() == 1); + } + + double squared_edge_length(Edge_handle e) const { + return squared_eucl_distance(complex_.point(complex_.first_vertex(e)), complex_.point(complex_.second_vertex(e))); + } + + double squared_eucl_distance(const Point& p1, const Point& p2) const { + return Geometry_trait::Squared_distance_d()(p1, p2); + } +}; + +#endif // UTILS_EDGE_COLLAPSOR_H_ |