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Diffstat (limited to 'src/Contraction/example/Garland_heckbert.cpp')
| -rw-r--r-- | src/Contraction/example/Garland_heckbert.cpp | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/src/Contraction/example/Garland_heckbert.cpp b/src/Contraction/example/Garland_heckbert.cpp new file mode 100644 index 00000000..9c0b5205 --- /dev/null +++ b/src/Contraction/example/Garland_heckbert.cpp @@ -0,0 +1,179 @@ +/* This file is part of the Gudhi Library - https://gudhi.inria.fr/ - which is released under MIT. + * See file LICENSE or go to https://gudhi.inria.fr/licensing/ for full license details. + * Author(s): David Salinas + * + * Copyright (C) 2014 Inria + * + * Modification(s): + * - YYYY/MM Author: Description of the modification + */ + + +#ifndef GARLAND_HECKBERT_H_ +#define GARLAND_HECKBERT_H_ + +#include <gudhi/Point.h> +#include <gudhi/Edge_contraction.h> +#include <gudhi/Skeleton_blocker.h> +#include <gudhi/Off_reader.h> + +#include <iostream> + +#include "Garland_heckbert/Error_quadric.h" + +struct Geometry_trait { + typedef Point_d Point; +}; + +/** + * The vertex stored in the complex contains a quadric. + */ +struct Garland_heckbert_traits + : public Gudhi::skeleton_blocker::Skeleton_blocker_simple_geometric_traits<Geometry_trait> { + public: + struct Garland_heckbert_vertex : public Simple_geometric_vertex { + Error_quadric<Geometry_trait::Point> quadric; + }; + typedef Garland_heckbert_vertex Graph_vertex; +}; + +using Complex = Gudhi::skeleton_blocker::Skeleton_blocker_geometric_complex< Garland_heckbert_traits >; +using EdgeProfile = Gudhi::contraction::Edge_profile<Complex>; +using Complex_contractor = Gudhi::contraction::Skeleton_blocker_contractor<Complex>; + +/** + * How the new vertex is placed after an edge collapse : here it is placed at + * the point minimizing the cost of the quadric. + */ +class GH_placement : public Gudhi::contraction::Placement_policy<EdgeProfile> { + Complex& complex_; + + public: + typedef Gudhi::contraction::Placement_policy<EdgeProfile>::Placement_type Placement_type; + + GH_placement(Complex& complex) : complex_(complex) { (void)complex_; } + + Placement_type operator()(const EdgeProfile& profile) const override { + auto sum_quad(profile.v0().quadric); + sum_quad += profile.v1().quadric; + + boost::optional<Point> min_quadric_pt(sum_quad.min_cost()); + if (min_quadric_pt) + return Placement_type(*min_quadric_pt); + else + return profile.p0(); + } +}; + +/** + * How much cost an edge collapse : here the costs is given by a quadric + * which expresses a squared distances with triangles planes. + */ +class GH_cost : public Gudhi::contraction::Cost_policy<EdgeProfile> { + Complex& complex_; + + public: + typedef Gudhi::contraction::Cost_policy<EdgeProfile>::Cost_type Cost_type; + + GH_cost(Complex& complex) : complex_(complex) { (void)complex_; } + + Cost_type operator()(EdgeProfile const& profile, boost::optional<Point> const& new_point) const override { + Cost_type res; + if (new_point) { + auto sum_quad(profile.v0().quadric); + sum_quad += profile.v1().quadric; + res = sum_quad.cost(*new_point); + } + return res; + } +}; + +/** + * Visitor that is called at several moment. + * Here we initializes the quadrics of every vertex at the on_started call back + * and we update them when contracting an edge (the quadric become the sum of both quadrics). + */ +class GH_visitor : public Gudhi::contraction::Contraction_visitor<EdgeProfile> { + Complex& complex_; + + public: + GH_visitor(Complex& complex) : complex_(complex) { (void)complex_; } + + // Compute quadrics for every vertex v + // The quadric of v consists in the sum of quadric + // of every triangles passing through v weighted by its area + + void on_started(Complex & complex) override { + for (auto v : complex.vertex_range()) { + auto & quadric_v(complex[v].quadric); + for (auto t : complex.triangle_range(v)) { + auto t_it = t.begin(); + const auto& p0(complex.point(*t_it++)); + const auto& p1(complex.point(*t_it++)); + const auto& p2(complex.point(*t_it++)); + quadric_v += Error_quadric<Point>(p0, p1, p2); + } + } + } + + /** + * @brief Called when an edge is about to be contracted and replaced by a vertex whose position is *placement. + */ + void on_contracting(EdgeProfile const &profile, boost::optional< Point > placement) + override { + profile.v0().quadric += profile.v1().quadric; + } +}; + +int main(int argc, char *argv[]) { + if (argc != 4) { + std::cerr << "Usage " << argv[0] << + " input.off output.off N to load the file input.off, contract N edges and save the result to output.off.\n"; + return EXIT_FAILURE; + } + + Complex complex; + typedef Complex::Vertex_handle Vertex_handle; + + // load the points + Gudhi::skeleton_blocker::Skeleton_blocker_off_reader<Complex> off_reader(argv[1], complex); + if (!off_reader.is_valid()) { + std::cerr << "Unable to read file:" << argv[1] << std::endl; + return EXIT_FAILURE; + } + + if (!complex.empty() && !(complex.point(Vertex_handle(0)).dimension() == 3)) { + std::cerr << "Only points of dimension 3 are supported." << std::endl; + return EXIT_FAILURE; + } + + std::cout << "Load complex with " << complex.num_vertices() << " vertices" << std::endl; + + int num_contractions = atoi(argv[3]); + + // constructs the contractor object with Garland Heckbert policies. + Complex_contractor contractor(complex, + new GH_cost(complex), + new GH_placement(complex), + Gudhi::contraction::make_link_valid_contraction<EdgeProfile>(), + new GH_visitor(complex)); + + std::cout << "Contract " << num_contractions << " edges" << std::endl; + contractor.contract_edges(num_contractions); + + std::cout << "Final complex has " << + complex.num_vertices() << " vertices, " << + complex.num_edges() << " edges and " << + complex.num_triangles() << " triangles." << std::endl; + + // write simplified complex + Gudhi::skeleton_blocker::Skeleton_blocker_off_writer<Complex> off_writer(argv[2], complex); + + return EXIT_SUCCESS; +} + +#endif // GARLAND_HECKBERT_H_ + + + + |