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Diffstat (limited to 'trunk/src/GudhUI/utils/Critical_points.h')
-rw-r--r-- | trunk/src/GudhUI/utils/Critical_points.h | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/trunk/src/GudhUI/utils/Critical_points.h b/trunk/src/GudhUI/utils/Critical_points.h new file mode 100644 index 00000000..2a18e079 --- /dev/null +++ b/trunk/src/GudhUI/utils/Critical_points.h @@ -0,0 +1,133 @@ +/* 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_CRITICAL_POINTS_H_ +#define UTILS_CRITICAL_POINTS_H_ + +#include <deque> +#include <utility> // for pair<> +#include <algorithm> // for sort + +#include "utils/Edge_contractor.h" + +/** + * Iteratively tries to anticollapse smallest edge non added so far. + * If its link is contractible then no topological change and else possible topological change. + * + * todo do a sparsification with some parameter eps while growing + */ +template<typename SkBlComplex> class Critical_points { + private: + SkBlComplex filled_complex_; + const SkBlComplex& input_complex_; + double max_length_; + std::ostream& stream_; + + public: + typedef typename SkBlComplex::Vertex_handle Vertex_handle; + typedef typename SkBlComplex::Edge_handle Edge_handle; + typedef typename std::pair<Vertex_handle, Vertex_handle> Edge; + + /** + * @brief check all pair of points with length smaller than max_length + */ + Critical_points(const SkBlComplex& input_complex, std::ostream& stream, double max_length) : + input_complex_(input_complex), max_length_(max_length), stream_(stream) { + std::deque<Edge> edges; + auto vertices = input_complex.vertex_range(); + for (auto p = vertices.begin(); p != vertices.end(); ++p) { + filled_complex_.add_vertex(input_complex.point(*p)); + for (auto q = p; ++q != vertices.end(); /**/) + if (squared_eucl_distance(input_complex.point(*p), input_complex.point(*q)) < max_length_ * max_length_) + edges.emplace_back(*p, *q); + } + + std::sort(edges.begin(), edges.end(), + [&](Edge e1, Edge e2) { + return squared_edge_length(e1) < squared_edge_length(e2); + }); + + anti_collapse_edges(edges); + } + + private: + double squared_eucl_distance(const Point& p1, const Point& p2) const { + return Geometry_trait::Squared_distance_d()(p1, p2); + } + + void anti_collapse_edges(const std::deque<Edge>& edges) { + unsigned pos = 0; + for (Edge e : edges) { + std::cout << "edge " << pos++ << "/" << edges.size() << "\n"; + auto eh = filled_complex_.add_edge(e.first, e.second); + int is_contractible(is_link_reducible(eh)); + + switch (is_contractible) { + case 0: + stream_ << "alpha=" << std::sqrt(squared_edge_length(e)) << " topological change" << std::endl; + break; + case 2: + stream_ << "alpha=" << std::sqrt(squared_edge_length(e)) << " maybe a topological change" << std::endl; + break; + default: + break; + } + } + } + + // 0 -> not + // 1 -> yes + // 2 -> maybe + + int is_link_reducible(Edge_handle e) { + auto link = filled_complex_.link(e); + + if (link.empty()) + return 0; + + Edge_contractor<Complex> contractor(link, link.num_vertices() - 1); + (void)contractor; + + if (link.num_connected_components() > 1) + // one than more CC -> not contractible + return 0; + + if (link.num_vertices() == 1) + // reduced to one point -> contractible + return 1; + else + // we dont know + return 2; + } + + double squared_edge_length(Edge_handle e) const { + return squared_eucl_distance(input_complex_.point(input_complex_.first_vertex(e)), + input_complex_.point(input_complex_.second_vertex(e))); + } + + double squared_edge_length(Edge e) const { + return squared_eucl_distance(input_complex_.point(e.first), input_complex_.point(e.second)); + } +}; + +#endif // UTILS_CRITICAL_POINTS_H_ |