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-rw-r--r--src/Alpha_complex/include/gudhi/Alpha_complex.h432
-rw-r--r--src/Alpha_complex/include/gudhi/Alpha_complex_3d.h579
-rw-r--r--src/Alpha_complex/include/gudhi/Alpha_complex_options.h33
3 files changed, 1044 insertions, 0 deletions
diff --git a/src/Alpha_complex/include/gudhi/Alpha_complex.h b/src/Alpha_complex/include/gudhi/Alpha_complex.h
new file mode 100644
index 00000000..8919cdb9
--- /dev/null
+++ b/src/Alpha_complex/include/gudhi/Alpha_complex.h
@@ -0,0 +1,432 @@
+/* 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): Vincent Rouvreau
+ *
+ * Copyright (C) 2015 Inria
+ *
+ * Modification(s):
+ * - 2019/08 Vincent Rouvreau: Fix issue #10 for CGAL and Eigen3
+ * - YYYY/MM Author: Description of the modification
+ */
+
+#ifndef ALPHA_COMPLEX_H_
+#define ALPHA_COMPLEX_H_
+
+#include <gudhi/Debug_utils.h>
+// to construct Alpha_complex from a OFF file of points
+#include <gudhi/Points_off_io.h>
+
+#include <stdlib.h>
+#include <math.h> // isnan, fmax
+
+#include <CGAL/Delaunay_triangulation.h>
+#include <CGAL/Epick_d.h>
+#include <CGAL/Spatial_sort_traits_adapter_d.h>
+#include <CGAL/property_map.h> // for CGAL::Identity_property_map
+#include <CGAL/NT_converter.h>
+#include <CGAL/version.h> // for CGAL_VERSION_NR
+
+#include <Eigen/src/Core/util/Macros.h> // for EIGEN_VERSION_AT_LEAST
+
+#include <iostream>
+#include <vector>
+#include <string>
+#include <limits> // NaN
+#include <map>
+#include <utility> // std::pair
+#include <stdexcept>
+#include <numeric> // for std::iota
+
+// Make compilation fail - required for external projects - https://github.com/GUDHI/gudhi-devel/issues/10
+#if CGAL_VERSION_NR < 1041101000
+# error Alpha_complex_3d is only available for CGAL >= 4.11
+#endif
+
+#if !EIGEN_VERSION_AT_LEAST(3,1,0)
+# error Alpha_complex_3d is only available for Eigen3 >= 3.1.0 installed with CGAL
+#endif
+
+namespace Gudhi {
+
+namespace alpha_complex {
+
+/**
+ * \class Alpha_complex Alpha_complex.h gudhi/Alpha_complex.h
+ * \brief Alpha complex data structure.
+ *
+ * \ingroup alpha_complex
+ *
+ * \details
+ * The data structure is constructing a CGAL Delaunay triangulation (for more informations on CGAL Delaunay
+ * triangulation, please refer to the corresponding chapter in page http://doc.cgal.org/latest/Triangulation/) from a
+ * range of points or from an OFF file (cf. Points_off_reader).
+ *
+ * Please refer to \ref alpha_complex for examples.
+ *
+ * The complex is a template class requiring an Epick_d <a target="_blank"
+ * href="http://doc.cgal.org/latest/Kernel_d/index.html#Chapter_dD_Geometry_Kernel">dD Geometry Kernel</a>
+ * \cite cgal:s-gkd-15b from CGAL as template, default value is <a target="_blank"
+ * href="http://doc.cgal.org/latest/Kernel_d/classCGAL_1_1Epick__d.html">CGAL::Epick_d</a>
+ * < <a target="_blank" href="http://doc.cgal.org/latest/Kernel_23/classCGAL_1_1Dynamic__dimension__tag.html">
+ * CGAL::Dynamic_dimension_tag </a> >
+ *
+ * \remark When Alpha_complex is constructed with an infinite value of alpha, the complex is a Delaunay complex.
+ *
+ */
+template<class Kernel = CGAL::Epick_d<CGAL::Dynamic_dimension_tag>>
+class Alpha_complex {
+ public:
+ // Add an int in TDS to save point index in the structure
+ typedef CGAL::Triangulation_data_structure<typename Kernel::Dimension,
+ CGAL::Triangulation_vertex<Kernel, std::ptrdiff_t>,
+ CGAL::Triangulation_full_cell<Kernel> > TDS;
+ /** \brief A Delaunay triangulation of a set of points in \f$ \mathbb{R}^D\f$.*/
+ typedef CGAL::Delaunay_triangulation<Kernel, TDS> Delaunay_triangulation;
+
+ /** \brief A point in Euclidean space.*/
+ typedef typename Kernel::Point_d Point_d;
+ /** \brief Geometric traits class that provides the geometric types and predicates needed by Delaunay
+ * triangulations.*/
+ typedef Kernel Geom_traits;
+
+ private:
+ typedef typename Kernel::Compute_squared_radius_d Squared_Radius;
+ typedef typename Kernel::Side_of_bounded_sphere_d Is_Gabriel;
+ typedef typename Kernel::Point_dimension_d Point_Dimension;
+
+ // Type required to compute squared radius, or side of bounded sphere on a vector of points.
+ typedef typename std::vector<Point_d> Vector_of_CGAL_points;
+
+ // Vertex_iterator type from CGAL.
+ typedef typename Delaunay_triangulation::Vertex_iterator CGAL_vertex_iterator;
+
+ // size_type type from CGAL.
+ typedef typename Delaunay_triangulation::size_type size_type;
+
+ // Map type to switch from simplex tree vertex handle to CGAL vertex iterator.
+ typedef typename std::map< std::size_t, CGAL_vertex_iterator > Vector_vertex_iterator;
+
+ private:
+ /** \brief Vertex iterator vector to switch from simplex tree vertex handle to CGAL vertex iterator.
+ * Vertex handles are inserted sequentially, starting at 0.*/
+ Vector_vertex_iterator vertex_handle_to_iterator_;
+ /** \brief Pointer on the CGAL Delaunay triangulation.*/
+ Delaunay_triangulation* triangulation_;
+ /** \brief Kernel for triangulation_ functions access.*/
+ Kernel kernel_;
+
+ public:
+ /** \brief Alpha_complex constructor from an OFF file name.
+ *
+ * Uses the Points_off_reader to construct the Delaunay triangulation required to initialize
+ * the Alpha_complex.
+ *
+ * Duplicate points are inserted once in the Alpha_complex. This is the reason why the vertices may be not contiguous.
+ *
+ * @param[in] off_file_name OFF file [path and] name.
+ */
+ Alpha_complex(const std::string& off_file_name)
+ : triangulation_(nullptr) {
+ Gudhi::Points_off_reader<Point_d> off_reader(off_file_name);
+ if (!off_reader.is_valid()) {
+ std::cerr << "Alpha_complex - Unable to read file " << off_file_name << "\n";
+ exit(-1); // ----- >>
+ }
+
+ init_from_range(off_reader.get_point_cloud());
+ }
+
+ /** \brief Alpha_complex constructor from a list of points.
+ *
+ * Duplicate points are inserted once in the Alpha_complex. This is the reason why the vertices may be not contiguous.
+ *
+ * @param[in] points Range of points to triangulate. Points must be in Kernel::Point_d
+ *
+ * The type InputPointRange must be a range for which std::begin and
+ * std::end return input iterators on a Kernel::Point_d.
+ */
+ template<typename InputPointRange >
+ Alpha_complex(const InputPointRange& points)
+ : triangulation_(nullptr) {
+ init_from_range(points);
+ }
+
+ /** \brief Alpha_complex destructor deletes the Delaunay triangulation.
+ */
+ ~Alpha_complex() {
+ delete triangulation_;
+ }
+
+ // Forbid copy/move constructor/assignment operator
+ Alpha_complex(const Alpha_complex& other) = delete;
+ Alpha_complex& operator= (const Alpha_complex& other) = delete;
+ Alpha_complex (Alpha_complex&& other) = delete;
+ Alpha_complex& operator= (Alpha_complex&& other) = delete;
+
+ /** \brief get_point returns the point corresponding to the vertex given as parameter.
+ *
+ * @param[in] vertex Vertex handle of the point to retrieve.
+ * @return The point found.
+ * @exception std::out_of_range In case vertex is not found (cf. std::vector::at).
+ */
+ const Point_d& get_point(std::size_t vertex) const {
+ return vertex_handle_to_iterator_.at(vertex)->point();
+ }
+
+ /** \brief number_of_vertices returns the number of vertices (same as the number of points).
+ *
+ * @return The number of vertices.
+ */
+ std::size_t number_of_vertices() const {
+ return vertex_handle_to_iterator_.size();
+ }
+
+ private:
+ template<typename InputPointRange >
+ void init_from_range(const InputPointRange& points) {
+ auto first = std::begin(points);
+ auto last = std::end(points);
+
+ if (first != last) {
+ // point_dimension function initialization
+ Point_Dimension point_dimension = kernel_.point_dimension_d_object();
+
+ // Delaunay triangulation is point dimension.
+ triangulation_ = new Delaunay_triangulation(point_dimension(*first));
+
+ std::vector<Point_d> point_cloud(first, last);
+
+ // Creates a vector {0, 1, ..., N-1}
+ std::vector<std::ptrdiff_t> indices(boost::counting_iterator<std::ptrdiff_t>(0),
+ boost::counting_iterator<std::ptrdiff_t>(point_cloud.size()));
+
+ typedef boost::iterator_property_map<typename std::vector<Point_d>::iterator,
+ CGAL::Identity_property_map<std::ptrdiff_t>> Point_property_map;
+ typedef CGAL::Spatial_sort_traits_adapter_d<Kernel, Point_property_map> Search_traits_d;
+
+ CGAL::spatial_sort(indices.begin(), indices.end(), Search_traits_d(std::begin(point_cloud)));
+
+ typename Delaunay_triangulation::Full_cell_handle hint;
+ for (auto index : indices) {
+ typename Delaunay_triangulation::Vertex_handle pos = triangulation_->insert(point_cloud[index], hint);
+ // Save index value as data to retrieve it after insertion
+ pos->data() = index;
+ hint = pos->full_cell();
+ }
+ // --------------------------------------------------------------------------------------------
+ // double map to retrieve simplex tree vertex handles from CGAL vertex iterator and vice versa
+ // Loop on triangulation vertices list
+ for (CGAL_vertex_iterator vit = triangulation_->vertices_begin(); vit != triangulation_->vertices_end(); ++vit) {
+ if (!triangulation_->is_infinite(*vit)) {
+#ifdef DEBUG_TRACES
+ std::cout << "Vertex insertion - " << vit->data() << " -> " << vit->point() << std::endl;
+#endif // DEBUG_TRACES
+ vertex_handle_to_iterator_.emplace(vit->data(), vit);
+ }
+ }
+ // --------------------------------------------------------------------------------------------
+ }
+ }
+
+ public:
+ /** \brief Inserts all Delaunay triangulation into the simplicial complex.
+ * It also computes the filtration values accordingly to the \ref createcomplexalgorithm
+ *
+ * \tparam SimplicialComplexForAlpha must meet `SimplicialComplexForAlpha` concept.
+ *
+ * @param[in] complex SimplicialComplexForAlpha to be created.
+ * @param[in] max_alpha_square maximum for alpha square value. Default value is +\f$\infty\f$, and there is very
+ * little point using anything else since it does not save time.
+ *
+ * @return true if creation succeeds, false otherwise.
+ *
+ * @pre Delaunay triangulation must be already constructed with dimension strictly greater than 0.
+ * @pre The simplicial complex must be empty (no vertices)
+ *
+ * Initialization can be launched once.
+ */
+ template <typename SimplicialComplexForAlpha,
+ typename Filtration_value = typename SimplicialComplexForAlpha::Filtration_value>
+ bool create_complex(SimplicialComplexForAlpha& complex,
+ Filtration_value max_alpha_square = std::numeric_limits<Filtration_value>::infinity()) {
+ // From SimplicialComplexForAlpha type required to insert into a simplicial complex (with or without subfaces).
+ typedef typename SimplicialComplexForAlpha::Vertex_handle Vertex_handle;
+ typedef typename SimplicialComplexForAlpha::Simplex_handle Simplex_handle;
+ typedef std::vector<Vertex_handle> Vector_vertex;
+
+ if (triangulation_ == nullptr) {
+ std::cerr << "Alpha_complex cannot create_complex from a NULL triangulation\n";
+ return false; // ----- >>
+ }
+ if (triangulation_->maximal_dimension() < 1) {
+ std::cerr << "Alpha_complex cannot create_complex from a zero-dimension triangulation\n";
+ return false; // ----- >>
+ }
+ if (complex.num_vertices() > 0) {
+ std::cerr << "Alpha_complex create_complex - complex is not empty\n";
+ return false; // ----- >>
+ }
+
+ // --------------------------------------------------------------------------------------------
+ // Simplex_tree construction from loop on triangulation finite full cells list
+ if (triangulation_->number_of_vertices() > 0) {
+ for (auto cit = triangulation_->finite_full_cells_begin();
+ cit != triangulation_->finite_full_cells_end();
+ ++cit) {
+ Vector_vertex vertexVector;
+#ifdef DEBUG_TRACES
+ std::cout << "Simplex_tree insertion ";
+#endif // DEBUG_TRACES
+ for (auto vit = cit->vertices_begin(); vit != cit->vertices_end(); ++vit) {
+ if (*vit != nullptr) {
+#ifdef DEBUG_TRACES
+ std::cout << " " << (*vit)->data();
+#endif // DEBUG_TRACES
+ // Vector of vertex construction for simplex_tree structure
+ vertexVector.push_back((*vit)->data());
+ }
+ }
+#ifdef DEBUG_TRACES
+ std::cout << std::endl;
+#endif // DEBUG_TRACES
+ // Insert each simplex and its subfaces in the simplex tree - filtration is NaN
+ complex.insert_simplex_and_subfaces(vertexVector, std::numeric_limits<double>::quiet_NaN());
+ }
+ }
+ // --------------------------------------------------------------------------------------------
+
+ // --------------------------------------------------------------------------------------------
+ // Will be re-used many times
+ Vector_of_CGAL_points pointVector;
+ // ### For i : d -> 0
+ for (int decr_dim = triangulation_->maximal_dimension(); decr_dim >= 0; decr_dim--) {
+ // ### Foreach Sigma of dim i
+ for (Simplex_handle f_simplex : complex.skeleton_simplex_range(decr_dim)) {
+ int f_simplex_dim = complex.dimension(f_simplex);
+ if (decr_dim == f_simplex_dim) {
+ pointVector.clear();
+#ifdef DEBUG_TRACES
+ std::cout << "Sigma of dim " << decr_dim << " is";
+#endif // DEBUG_TRACES
+ for (auto vertex : complex.simplex_vertex_range(f_simplex)) {
+ pointVector.push_back(get_point(vertex));
+#ifdef DEBUG_TRACES
+ std::cout << " " << vertex;
+#endif // DEBUG_TRACES
+ }
+#ifdef DEBUG_TRACES
+ std::cout << std::endl;
+#endif // DEBUG_TRACES
+ // ### If filt(Sigma) is NaN : filt(Sigma) = alpha(Sigma)
+ if (std::isnan(complex.filtration(f_simplex))) {
+ Filtration_value alpha_complex_filtration = 0.0;
+ // No need to compute squared_radius on a single point - alpha is 0.0
+ if (f_simplex_dim > 0) {
+ // squared_radius function initialization
+ Squared_Radius squared_radius = kernel_.compute_squared_radius_d_object();
+ CGAL::NT_converter<typename Geom_traits::FT, Filtration_value> cv;
+
+ alpha_complex_filtration = cv(squared_radius(pointVector.begin(), pointVector.end()));
+ }
+ complex.assign_filtration(f_simplex, alpha_complex_filtration);
+#ifdef DEBUG_TRACES
+ std::cout << "filt(Sigma) is NaN : filt(Sigma) =" << complex.filtration(f_simplex) << std::endl;
+#endif // DEBUG_TRACES
+ }
+ // No need to propagate further, unweighted points all have value 0
+ if (decr_dim > 1)
+ propagate_alpha_filtration(complex, f_simplex);
+ }
+ }
+ }
+ // --------------------------------------------------------------------------------------------
+
+ // --------------------------------------------------------------------------------------------
+ // As Alpha value is an approximation, we have to make filtration non decreasing while increasing the dimension
+ complex.make_filtration_non_decreasing();
+ // Remove all simplices that have a filtration value greater than max_alpha_square
+ complex.prune_above_filtration(max_alpha_square);
+ // --------------------------------------------------------------------------------------------
+ return true;
+ }
+
+ private:
+ template <typename SimplicialComplexForAlpha, typename Simplex_handle>
+ void propagate_alpha_filtration(SimplicialComplexForAlpha& complex, Simplex_handle f_simplex) {
+ // From SimplicialComplexForAlpha type required to assign filtration values.
+ typedef typename SimplicialComplexForAlpha::Filtration_value Filtration_value;
+#ifdef DEBUG_TRACES
+ typedef typename SimplicialComplexForAlpha::Vertex_handle Vertex_handle;
+#endif // DEBUG_TRACES
+
+ // ### Foreach Tau face of Sigma
+ for (auto f_boundary : complex.boundary_simplex_range(f_simplex)) {
+#ifdef DEBUG_TRACES
+ std::cout << " | --------------------------------------------------\n";
+ std::cout << " | Tau ";
+ for (auto vertex : complex.simplex_vertex_range(f_boundary)) {
+ std::cout << vertex << " ";
+ }
+ std::cout << "is a face of Sigma\n";
+ std::cout << " | isnan(complex.filtration(Tau)=" << std::isnan(complex.filtration(f_boundary)) << std::endl;
+#endif // DEBUG_TRACES
+ // ### If filt(Tau) is not NaN
+ if (!std::isnan(complex.filtration(f_boundary))) {
+ // ### filt(Tau) = fmin(filt(Tau), filt(Sigma))
+ Filtration_value alpha_complex_filtration = fmin(complex.filtration(f_boundary),
+ complex.filtration(f_simplex));
+ complex.assign_filtration(f_boundary, alpha_complex_filtration);
+#ifdef DEBUG_TRACES
+ std::cout << " | filt(Tau) = fmin(filt(Tau), filt(Sigma)) = " << complex.filtration(f_boundary) << std::endl;
+#endif // DEBUG_TRACES
+ // ### Else
+ } else {
+ // insert the Tau points in a vector for is_gabriel function
+ Vector_of_CGAL_points pointVector;
+#ifdef DEBUG_TRACES
+ Vertex_handle vertexForGabriel = Vertex_handle();
+#endif // DEBUG_TRACES
+ for (auto vertex : complex.simplex_vertex_range(f_boundary)) {
+ pointVector.push_back(get_point(vertex));
+ }
+ // Retrieve the Sigma point that is not part of Tau - parameter for is_gabriel function
+ Point_d point_for_gabriel;
+ for (auto vertex : complex.simplex_vertex_range(f_simplex)) {
+ point_for_gabriel = get_point(vertex);
+ if (std::find(pointVector.begin(), pointVector.end(), point_for_gabriel) == pointVector.end()) {
+#ifdef DEBUG_TRACES
+ // vertex is not found in Tau
+ vertexForGabriel = vertex;
+#endif // DEBUG_TRACES
+ // No need to continue loop
+ break;
+ }
+ }
+ // is_gabriel function initialization
+ Is_Gabriel is_gabriel = kernel_.side_of_bounded_sphere_d_object();
+ bool is_gab = is_gabriel(pointVector.begin(), pointVector.end(), point_for_gabriel)
+ != CGAL::ON_BOUNDED_SIDE;
+#ifdef DEBUG_TRACES
+ std::cout << " | Tau is_gabriel(Sigma)=" << is_gab << " - vertexForGabriel=" << vertexForGabriel << std::endl;
+#endif // DEBUG_TRACES
+ // ### If Tau is not Gabriel of Sigma
+ if (false == is_gab) {
+ // ### filt(Tau) = filt(Sigma)
+ Filtration_value alpha_complex_filtration = complex.filtration(f_simplex);
+ complex.assign_filtration(f_boundary, alpha_complex_filtration);
+#ifdef DEBUG_TRACES
+ std::cout << " | filt(Tau) = filt(Sigma) = " << complex.filtration(f_boundary) << std::endl;
+#endif // DEBUG_TRACES
+ }
+ }
+ }
+ }
+};
+
+} // namespace alpha_complex
+
+namespace alphacomplex = alpha_complex;
+
+} // namespace Gudhi
+
+#endif // ALPHA_COMPLEX_H_
diff --git a/src/Alpha_complex/include/gudhi/Alpha_complex_3d.h b/src/Alpha_complex/include/gudhi/Alpha_complex_3d.h
new file mode 100644
index 00000000..13ebb9c1
--- /dev/null
+++ b/src/Alpha_complex/include/gudhi/Alpha_complex_3d.h
@@ -0,0 +1,579 @@
+/* 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): Vincent Rouvreau
+ *
+ * Copyright (C) 2018 Inria
+ *
+ * Modification(s):
+ * - 2019/08 Vincent Rouvreau: Fix issue #10 for CGAL and Eigen3
+ * - YYYY/MM Author: Description of the modification
+ */
+
+#ifndef ALPHA_COMPLEX_3D_H_
+#define ALPHA_COMPLEX_3D_H_
+
+#include <boost/version.hpp>
+#include <boost/variant.hpp>
+
+#include <gudhi/Debug_utils.h>
+#include <gudhi/Alpha_complex_options.h>
+
+#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
+#include <CGAL/Exact_predicates_exact_constructions_kernel.h>
+#include <CGAL/Delaunay_triangulation_3.h>
+#include <CGAL/Periodic_3_Delaunay_triangulation_traits_3.h>
+#include <CGAL/Periodic_3_Delaunay_triangulation_3.h>
+#include <CGAL/Periodic_3_regular_triangulation_traits_3.h>
+#include <CGAL/Periodic_3_regular_triangulation_3.h>
+#include <CGAL/Regular_triangulation_3.h>
+#include <CGAL/Alpha_shape_3.h>
+#include <CGAL/Alpha_shape_cell_base_3.h>
+#include <CGAL/Alpha_shape_vertex_base_3.h>
+
+#include <CGAL/Object.h>
+#include <CGAL/tuple.h>
+#include <CGAL/iterator.h>
+#include <CGAL/version.h> // for CGAL_VERSION_NR
+
+#include <Eigen/src/Core/util/Macros.h> // for EIGEN_VERSION_AT_LEAST
+
+#include <boost/container/static_vector.hpp>
+
+#include <iostream>
+#include <vector>
+#include <unordered_map>
+#include <stdexcept>
+#include <cstddef>
+#include <memory> // for std::unique_ptr
+#include <type_traits> // for std::conditional and std::enable_if
+#include <limits> // for numeric_limits<>
+
+// Make compilation fail - required for external projects - https://github.com/GUDHI/gudhi-devel/issues/10
+#if CGAL_VERSION_NR < 1041101000
+# error Alpha_complex_3d is only available for CGAL >= 4.11
+#endif
+
+#if !EIGEN_VERSION_AT_LEAST(3,1,0)
+# error Alpha_complex_3d is only available for Eigen3 >= 3.1.0 installed with CGAL
+#endif
+
+namespace Gudhi {
+
+namespace alpha_complex {
+
+#ifdef GUDHI_CAN_USE_CXX11_THREAD_LOCAL
+thread_local
+#endif // GUDHI_CAN_USE_CXX11_THREAD_LOCAL
+ double RELATIVE_PRECISION_OF_TO_DOUBLE = 0.00001;
+
+// Value_from_iterator returns the filtration value from an iterator on alpha shapes values
+//
+// FAST SAFE EXACT
+// CGAL::to_double(*iterator) CGAL::to_double(*iterator) CGAL::to_double(iterator->exact())
+
+template <complexity Complexity>
+struct Value_from_iterator {
+ template <typename Iterator>
+ static double perform(Iterator it) {
+ // Default behaviour
+ return CGAL::to_double(*it);
+ }
+};
+
+template <>
+struct Value_from_iterator<complexity::EXACT> {
+ template <typename Iterator>
+ static double perform(Iterator it) {
+ return CGAL::to_double(it->exact());
+ }
+};
+
+/**
+ * \class Alpha_complex_3d
+ * \brief Alpha complex data structure for 3d specific case.
+ *
+ * \ingroup alpha_complex
+ *
+ * \details
+ * The data structure is constructing a <a href="https://doc.cgal.org/latest/Alpha_shapes_3/index.html">CGAL 3D Alpha
+ * Shapes</a> from a range of points (can be read from an OFF file, cf. Points_off_reader).
+ * Duplicate points are inserted once in the Alpha_complex. This is the reason why the vertices may be not contiguous.
+ *
+ * \tparam Complexity shall be `Gudhi::alpha_complex::complexity` type. Default value is
+ * `Gudhi::alpha_complex::complexity::SAFE`.
+ *
+ * \tparam Weighted Boolean used to set/unset the weighted version of Alpha_complex_3d. Default value is false.
+ *
+ * \tparam Periodic Boolean used to set/unset the periodic version of Alpha_complex_3d. Default value is false.
+ *
+ * For the weighted version, weights values are explained on CGAL
+ * <a href="https://doc.cgal.org/latest/Alpha_shapes_3/index.html#title0">Alpha shapes 3d</a> and
+ * <a href="https://doc.cgal.org/latest/Triangulation_3/index.html#Triangulation3secclassRegulartriangulation">Regular
+ * triangulation</a> documentation.
+ *
+ * For the periodic version, refer to the
+ * <a href="https://doc.cgal.org/latest/Periodic_3_triangulation_3/index.html">CGAL’s 3D Periodic Triangulations User
+ * Manual </a> for more details.
+ * The periodicity is defined by an iso-oriented cuboid with diagonal opposite vertices (x_min, y_min, z_min) and
+ * (x_max, y_max, z_max).
+ *
+ * Please refer to \ref alpha_complex for examples.
+ *
+ * \remark When Alpha_complex_3d is constructed with an infinite value of alpha (default value), the complex is a
+ * 3d Delaunay complex.
+ *
+ */
+template <complexity Complexity = complexity::SAFE, bool Weighted = false, bool Periodic = false>
+class Alpha_complex_3d {
+ // Epick = Exact_predicates_inexact_constructions_kernel
+ // Epeck = Exact_predicates_exact_constructions_kernel
+ // Exact_alpha_comparison_tag = exact version of CGAL Alpha_shape_3 and of its objects (Alpha_shape_vertex_base_3 and
+ // Alpha_shape_cell_base_3). Not available if weighted or periodic.
+ // Can be CGAL::Tag_false or CGAL::Tag_true. Default is False.
+ // cf. https://doc.cgal.org/latest/Alpha_shapes_3/classCGAL_1_1Alpha__shape__3.html
+ //
+ // We could use Epick + CGAL::Tag_true for not weighted nor periodic, but during benchmark, we found a bug
+ // https://github.com/CGAL/cgal/issues/3460
+ // This is the reason we only use Epick + CGAL::Tag_false, or Epeck
+ //
+ // FAST SAFE EXACT
+ // Epick + CGAL::Tag_false Epeck Epeck
+ using Predicates = typename std::conditional<(Complexity == complexity::FAST),
+ CGAL::Exact_predicates_inexact_constructions_kernel,
+ CGAL::Exact_predicates_exact_constructions_kernel>::type;
+
+ // The other way to do a conditional type. Here there are 3 possibilities
+ template <typename Predicates, bool Weighted_version, bool Periodic_version>
+ struct Kernel_3 {};
+
+ template <typename Predicates, bool Is_periodic>
+ struct Kernel_3<Predicates, Is_periodic, false> {
+ using Kernel = Predicates;
+ };
+
+ template <typename Predicates>
+ struct Kernel_3<Predicates, false, true> {
+ using Kernel = CGAL::Periodic_3_Delaunay_triangulation_traits_3<Predicates>;
+ };
+ template <typename Predicates>
+ struct Kernel_3<Predicates, true, true> {
+ using Kernel = CGAL::Periodic_3_regular_triangulation_traits_3<Predicates>;
+ };
+
+ using Kernel = typename Kernel_3<Predicates, Weighted, Periodic>::Kernel;
+
+ using TdsVb = typename std::conditional<Periodic, CGAL::Periodic_3_triangulation_ds_vertex_base_3<>,
+ CGAL::Triangulation_ds_vertex_base_3<>>::type;
+
+ using Tvb = typename std::conditional<Weighted, CGAL::Regular_triangulation_vertex_base_3<Kernel, TdsVb>,
+ CGAL::Triangulation_vertex_base_3<Kernel, TdsVb>>::type;
+
+ using Vb = CGAL::Alpha_shape_vertex_base_3<Kernel, Tvb>;
+
+ using TdsCb = typename std::conditional<Periodic, CGAL::Periodic_3_triangulation_ds_cell_base_3<>,
+ CGAL::Triangulation_ds_cell_base_3<>>::type;
+
+ using Tcb = typename std::conditional<Weighted, CGAL::Regular_triangulation_cell_base_3<Kernel, TdsCb>,
+ CGAL::Triangulation_cell_base_3<Kernel, TdsCb>>::type;
+
+ using Cb = CGAL::Alpha_shape_cell_base_3<Kernel, Tcb>;
+ using Tds = CGAL::Triangulation_data_structure_3<Vb, Cb>;
+
+ // The other way to do a conditional type. Here there 4 possibilities, cannot use std::conditional
+ template <typename Kernel, typename Tds, bool Weighted_version, bool Periodic_version>
+ struct Triangulation_3 {};
+
+ template <typename Kernel, typename Tds>
+ struct Triangulation_3<Kernel, Tds, false, false> {
+ using Dt = CGAL::Delaunay_triangulation_3<Kernel, Tds>;
+ using Weighted_point_3 = void;
+ };
+ template <typename Kernel, typename Tds>
+ struct Triangulation_3<Kernel, Tds, true, false> {
+ using Dt = CGAL::Regular_triangulation_3<Kernel, Tds>;
+ using Weighted_point_3 = typename Dt::Weighted_point;
+ };
+ template <typename Kernel, typename Tds>
+ struct Triangulation_3<Kernel, Tds, false, true> {
+ using Dt = CGAL::Periodic_3_Delaunay_triangulation_3<Kernel, Tds>;
+ using Weighted_point_3 = void;
+ };
+ template <typename Kernel, typename Tds>
+ struct Triangulation_3<Kernel, Tds, true, true> {
+ using Dt = CGAL::Periodic_3_regular_triangulation_3<Kernel, Tds>;
+ using Weighted_point_3 = typename Dt::Weighted_point;
+ };
+
+ /** \brief Is either Delaunay_triangulation_3 (Weighted = false and Periodic = false),
+ * Regular_triangulation_3 (Weighted = true and Periodic = false),
+ * Periodic_3_Delaunay_triangulation_3 (Weighted = false and Periodic = true)
+ * or Periodic_3_regular_triangulation_3 (Weighted = true and Periodic = true).
+ *
+ * This type is required by `Gudhi::alpha_complex::Alpha_complex_3d::Alpha_shape_3`.
+ * */
+ using Dt = typename Triangulation_3<Kernel, Tds, Weighted, Periodic>::Dt;
+
+ public:
+ /** \brief The <a href="https://doc.cgal.org/latest/Alpha_shapes_3/classCGAL_1_1Alpha__shape__3.html">CGAL 3D Alpha
+ * Shapes</a> type.
+ *
+ * The `Gudhi::alpha_complex::Alpha_complex_3d` is a wrapper on top of this class to ease the standard, weighted
+ * and/or periodic build of the Alpha complex 3d.*/
+ using Alpha_shape_3 = CGAL::Alpha_shape_3<Dt>;
+
+ /** \brief The alpha values type.
+ * Must be compatible with double. */
+ using FT = typename Alpha_shape_3::FT;
+
+ /** \brief Gives public access to the Point_3 type. Here is a Point_3 constructor example:
+\code{.cpp}
+using Alpha_complex_3d = Gudhi::alpha_complex::Alpha_complex_3d<Gudhi::alpha_complex::complexity::SAFE, false, false>;
+
+// x0 = 1., y0 = -1.1, z0 = -1..
+Alpha_complex_3d::Point_3 p0(1., -1.1, -1.);
+\endcode
+ * */
+ using Point_3 = typename Kernel::Point_3;
+
+ /** \brief Gives public access to the Weighted_point_3 type. A Weighted point can be constructed as follows:
+\code{.cpp}
+using Weighted_alpha_complex_3d =
+ Gudhi::alpha_complex::Alpha_complex_3d<Gudhi::alpha_complex::complexity::SAFE, true, false>;
+
+// x0 = 1., y0 = -1.1, z0 = -1., weight = 4.
+Weighted_alpha_complex_3d::Weighted_point_3 wp0(Weighted_alpha_complex_3d::Point_3(1., -1.1, -1.), 4.);
+\endcode
+ *
+ * Note: This type is defined to void if Alpha complex is not weighted.
+ *
+ * */
+ using Weighted_point_3 = typename Triangulation_3<Kernel, Tds, Weighted, Periodic>::Weighted_point_3;
+
+ private:
+ using Dispatch =
+ CGAL::Dispatch_output_iterator<CGAL::cpp11::tuple<CGAL::Object, FT>,
+ CGAL::cpp11::tuple<std::back_insert_iterator<std::vector<CGAL::Object>>,
+ std::back_insert_iterator<std::vector<FT>>>>;
+
+ using Cell_handle = typename Alpha_shape_3::Cell_handle;
+ using Facet = typename Alpha_shape_3::Facet;
+ using Edge = typename Alpha_shape_3::Edge;
+ using Alpha_vertex_handle = typename Alpha_shape_3::Vertex_handle;
+ using Vertex_list = boost::container::static_vector<Alpha_vertex_handle, 4>;
+
+ public:
+ /** \brief Alpha_complex constructor from a list of points.
+ *
+ * @param[in] points Range of points to triangulate. Points must be in `Alpha_complex_3d::Point_3` or
+ * `Alpha_complex_3d::Weighted_point_3`.
+ *
+ * @pre Available if Alpha_complex_3d is not Periodic.
+ *
+ * The type InputPointRange must be a range for which std::begin and std::end return input iterators on a
+ * `Alpha_complex_3d::Point_3` or a `Alpha_complex_3d::Weighted_point_3`.
+ */
+ template <typename InputPointRange>
+ Alpha_complex_3d(const InputPointRange& points) {
+ static_assert(!Periodic, "This constructor is not available for periodic versions of Alpha_complex_3d");
+
+ alpha_shape_3_ptr_ = std::unique_ptr<Alpha_shape_3>(
+ new Alpha_shape_3(std::begin(points), std::end(points), 0, Alpha_shape_3::GENERAL));
+ }
+
+ /** \brief Alpha_complex constructor from a list of points and associated weights.
+ *
+ * @exception std::invalid_argument In debug mode, if points and weights do not have the same size.
+ *
+ * @param[in] points Range of points to triangulate. Points must be in `Alpha_complex_3d::Point_3`.
+ * @param[in] weights Range of weights on points. Weights shall be in double.
+ *
+ * @pre Available if Alpha_complex_3d is Weighted and not Periodic.
+ *
+ * The type InputPointRange must be a range for which std::begin and
+ * std::end return input iterators on a `Alpha_complex_3d::Point_3`.
+ * The type WeightRange must be a range for which std::begin and
+ * std::end return an input iterator on a double.
+ */
+ template <typename InputPointRange, typename WeightRange>
+ Alpha_complex_3d(const InputPointRange& points, WeightRange weights) {
+ static_assert(Weighted, "This constructor is not available for non-weighted versions of Alpha_complex_3d");
+ static_assert(!Periodic, "This constructor is not available for periodic versions of Alpha_complex_3d");
+ GUDHI_CHECK((weights.size() == points.size()),
+ std::invalid_argument("Points number in range different from weights range number"));
+
+ std::vector<Weighted_point_3> weighted_points_3;
+
+ std::size_t index = 0;
+ weighted_points_3.reserve(points.size());
+ while ((index < weights.size()) && (index < points.size())) {
+ weighted_points_3.push_back(Weighted_point_3(points[index], weights[index]));
+ index++;
+ }
+
+ alpha_shape_3_ptr_ = std::unique_ptr<Alpha_shape_3>(
+ new Alpha_shape_3(std::begin(weighted_points_3), std::end(weighted_points_3), 0, Alpha_shape_3::GENERAL));
+ }
+
+ /** \brief Alpha_complex constructor from a list of points and an iso-cuboid coordinates.
+ *
+ * @exception std::invalid_argument In debug mode, if the size of the cuboid in every directions is not the same.
+ *
+ * @param[in] points Range of points to triangulate. Points must be in `Alpha_complex_3d::Point_3` or
+ * `Alpha_complex_3d::Weighted_point_3`.
+ * @param[in] x_min Iso-oriented cuboid x_min.
+ * @param[in] y_min Iso-oriented cuboid y_min.
+ * @param[in] z_min Iso-oriented cuboid z_min.
+ * @param[in] x_max Iso-oriented cuboid x_max.
+ * @param[in] y_max Iso-oriented cuboid y_max.
+ * @param[in] z_max Iso-oriented cuboid z_max.
+ *
+ * @pre Available if Alpha_complex_3d is Periodic.
+ *
+ * The type InputPointRange must be a range for which std::begin and std::end return input iterators on a
+ * `Alpha_complex_3d::Point_3` or a `Alpha_complex_3d::Weighted_point_3`.
+ *
+ * @note In weighted version, please check weights are greater than zero, and lower than 1/64*cuboid length
+ * squared.
+ */
+ template <typename InputPointRange>
+ Alpha_complex_3d(const InputPointRange& points, FT x_min, FT y_min,
+ FT z_min, FT x_max, FT y_max, FT z_max) {
+ static_assert(Periodic, "This constructor is not available for non-periodic versions of Alpha_complex_3d");
+ // Checking if the cuboid is the same in x,y and z direction. If not, CGAL will not process it.
+ GUDHI_CHECK(
+ (x_max - x_min == y_max - y_min) && (x_max - x_min == z_max - z_min) && (z_max - z_min == y_max - y_min),
+ std::invalid_argument("The size of the cuboid in every directions is not the same."));
+
+ // Define the periodic cube
+ Dt pdt(typename Kernel::Iso_cuboid_3(x_min, y_min, z_min, x_max, y_max, z_max));
+ // Heuristic for inserting large point sets (if pts is reasonably large)
+ pdt.insert(std::begin(points), std::end(points), true);
+ // As pdt won't be modified anymore switch to 1-sheeted cover if possible
+ if (!pdt.is_triangulation_in_1_sheet()) {
+ throw std::invalid_argument("Unable to construct a triangulation within a single periodic domain.");
+ }
+ pdt.convert_to_1_sheeted_covering();
+
+ // alpha shape construction from points. CGAL has a strange behavior in REGULARIZED mode. This is the default mode
+ // Maybe need to set it to GENERAL mode
+ alpha_shape_3_ptr_ = std::unique_ptr<Alpha_shape_3>(new Alpha_shape_3(pdt, 0, Alpha_shape_3::GENERAL));
+ }
+
+ /** \brief Alpha_complex constructor from a list of points, associated weights and an iso-cuboid coordinates.
+ *
+ * @exception std::invalid_argument In debug mode, if points and weights do not have the same size.
+ * @exception std::invalid_argument In debug mode, if the size of the cuboid in every directions is not the same.
+ * @exception std::invalid_argument In debug mode, if a weight is negative, zero, or greater than 1/64*cuboid length
+ * squared.
+ *
+ * @param[in] points Range of points to triangulate. Points must be in `Alpha_complex_3d::Point_3`.
+ * @param[in] weights Range of weights on points. Weights shall be in double.
+ * @param[in] x_min Iso-oriented cuboid x_min.
+ * @param[in] y_min Iso-oriented cuboid y_min.
+ * @param[in] z_min Iso-oriented cuboid z_min.
+ * @param[in] x_max Iso-oriented cuboid x_max.
+ * @param[in] y_max Iso-oriented cuboid y_max.
+ * @param[in] z_max Iso-oriented cuboid z_max.
+ *
+ * @pre Available if Alpha_complex_3d is Weighted and Periodic.
+ *
+ * The type InputPointRange must be a range for which std::begin and
+ * std::end return input iterators on a `Alpha_complex_3d::Point_3`.
+ * The type WeightRange must be a range for which std::begin and
+ * std::end return an input iterator on a double.
+ * The type of x_min, y_min, z_min, x_max, y_max and z_max must be a double.
+ */
+ template <typename InputPointRange, typename WeightRange>
+ Alpha_complex_3d(const InputPointRange& points, WeightRange weights, FT x_min, FT y_min,
+ FT z_min, FT x_max, FT y_max, FT z_max) {
+ static_assert(Weighted, "This constructor is not available for non-weighted versions of Alpha_complex_3d");
+ static_assert(Periodic, "This constructor is not available for non-periodic versions of Alpha_complex_3d");
+ GUDHI_CHECK((weights.size() == points.size()),
+ std::invalid_argument("Points number in range different from weights range number"));
+ // Checking if the cuboid is the same in x,y and z direction. If not, CGAL will not process it.
+ GUDHI_CHECK(
+ (x_max - x_min == y_max - y_min) && (x_max - x_min == z_max - z_min) && (z_max - z_min == y_max - y_min),
+ std::invalid_argument("The size of the cuboid in every directions is not the same."));
+
+ std::vector<Weighted_point_3> weighted_points_3;
+
+ std::size_t index = 0;
+ weighted_points_3.reserve(points.size());
+
+#ifdef GUDHI_DEBUG
+ // Defined in GUDHI_DEBUG to avoid unused variable warning for GUDHI_CHECK
+ FT maximal_possible_weight = 0.015625 * (x_max - x_min) * (x_max - x_min);
+#endif
+
+ while ((index < weights.size()) && (index < points.size())) {
+ GUDHI_CHECK((weights[index] < maximal_possible_weight) && (weights[index] >= 0),
+ std::invalid_argument("Invalid weight at index " + std::to_string(index + 1) +
+ ". Must be positive and less than maximal possible weight = 1/64*cuboid length "
+ "squared, which is not an acceptable input."));
+ weighted_points_3.push_back(Weighted_point_3(points[index], weights[index]));
+ index++;
+ }
+
+ // Define the periodic cube
+ Dt pdt(typename Kernel::Iso_cuboid_3(x_min, y_min, z_min, x_max, y_max, z_max));
+ // Heuristic for inserting large point sets (if pts is reasonably large)
+ pdt.insert(std::begin(weighted_points_3), std::end(weighted_points_3), true);
+ // As pdt won't be modified anymore switch to 1-sheeted cover if possible
+ if (!pdt.is_triangulation_in_1_sheet()) {
+ throw std::invalid_argument("Unable to construct a triangulation within a single periodic domain.");
+ }
+ pdt.convert_to_1_sheeted_covering();
+
+ // alpha shape construction from points. CGAL has a strange behavior in REGULARIZED mode. This is the default mode
+ // Maybe need to set it to GENERAL mode
+ alpha_shape_3_ptr_ = std::unique_ptr<Alpha_shape_3>(new Alpha_shape_3(pdt, 0, Alpha_shape_3::GENERAL));
+ }
+
+ /** \brief Inserts all Delaunay triangulation into the simplicial complex.
+ * It also computes the filtration values accordingly to the \ref createcomplexalgorithm
+ *
+ * \tparam SimplicialComplexForAlpha3d must meet `SimplicialComplexForAlpha3d` concept.
+ *
+ * @param[in] complex SimplicialComplexForAlpha3d to be created.
+ * @param[in] max_alpha_square maximum for alpha square value. Default value is +\f$\infty\f$, and there is very
+ * little point using anything else since it does not save time.
+ *
+ * @return true if creation succeeds, false otherwise.
+ *
+ * @pre The simplicial complex must be empty (no vertices).
+ *
+ */
+ template <typename SimplicialComplexForAlpha3d,
+ typename Filtration_value = typename SimplicialComplexForAlpha3d::Filtration_value>
+ bool create_complex(SimplicialComplexForAlpha3d& complex,
+ Filtration_value max_alpha_square = std::numeric_limits<Filtration_value>::infinity()) {
+ if (complex.num_vertices() > 0) {
+ std::cerr << "Alpha_complex_3d create_complex - complex is not empty\n";
+ return false; // ----- >>
+ }
+
+ // using Filtration_value = typename SimplicialComplexForAlpha3d::Filtration_value;
+ using Complex_vertex_handle = typename SimplicialComplexForAlpha3d::Vertex_handle;
+ using Alpha_shape_simplex_tree_map = std::unordered_map<Alpha_vertex_handle, Complex_vertex_handle>;
+ using Simplex_tree_vector_vertex = std::vector<Complex_vertex_handle>;
+
+#ifdef DEBUG_TRACES
+ std::size_t count_vertices = 0;
+ std::size_t count_edges = 0;
+ std::size_t count_facets = 0;
+ std::size_t count_cells = 0;
+#endif // DEBUG_TRACES
+ std::vector<CGAL::Object> objects;
+ std::vector<FT> alpha_values;
+
+ Dispatch dispatcher = CGAL::dispatch_output<CGAL::Object, FT>(std::back_inserter(objects),
+ std::back_inserter(alpha_values));
+
+ alpha_shape_3_ptr_->filtration_with_alpha_values(dispatcher);
+#ifdef DEBUG_TRACES
+ std::cout << "filtration_with_alpha_values returns : " << objects.size() << " objects" << std::endl;
+#endif // DEBUG_TRACES
+
+ Alpha_shape_simplex_tree_map map_cgal_simplex_tree;
+ using Alpha_value_iterator = typename std::vector<FT>::const_iterator;
+ Alpha_value_iterator alpha_value_iterator = alpha_values.begin();
+ for (auto object_iterator : objects) {
+ Vertex_list vertex_list;
+
+ // Retrieve Alpha shape vertex list from object
+ if (const Cell_handle* cell = CGAL::object_cast<Cell_handle>(&object_iterator)) {
+ for (auto i = 0; i < 4; i++) {
+#ifdef DEBUG_TRACES
+ std::cout << "from cell[" << i << "]=" << (*cell)->vertex(i)->point() << std::endl;
+#endif // DEBUG_TRACES
+ vertex_list.push_back((*cell)->vertex(i));
+ }
+#ifdef DEBUG_TRACES
+ count_cells++;
+#endif // DEBUG_TRACES
+ } else if (const Facet* facet = CGAL::object_cast<Facet>(&object_iterator)) {
+ for (auto i = 0; i < 4; i++) {
+ if ((*facet).second != i) {
+#ifdef DEBUG_TRACES
+ std::cout << "from facet=[" << i << "]" << (*facet).first->vertex(i)->point() << std::endl;
+#endif // DEBUG_TRACES
+ vertex_list.push_back((*facet).first->vertex(i));
+ }
+ }
+#ifdef DEBUG_TRACES
+ count_facets++;
+#endif // DEBUG_TRACES
+ } else if (const Edge* edge = CGAL::object_cast<Edge>(&object_iterator)) {
+ for (auto i : {(*edge).second, (*edge).third}) {
+#ifdef DEBUG_TRACES
+ std::cout << "from edge[" << i << "]=" << (*edge).first->vertex(i)->point() << std::endl;
+#endif // DEBUG_TRACES
+ vertex_list.push_back((*edge).first->vertex(i));
+ }
+#ifdef DEBUG_TRACES
+ count_edges++;
+#endif // DEBUG_TRACES
+ } else if (const Alpha_vertex_handle* vertex = CGAL::object_cast<Alpha_vertex_handle>(&object_iterator)) {
+#ifdef DEBUG_TRACES
+ count_vertices++;
+ std::cout << "from vertex=" << (*vertex)->point() << std::endl;
+#endif // DEBUG_TRACES
+ vertex_list.push_back((*vertex));
+ }
+ // Construction of the vector of simplex_tree vertex from list of alpha_shapes vertex
+ Simplex_tree_vector_vertex the_simplex;
+ for (auto the_alpha_shape_vertex : vertex_list) {
+ auto the_map_iterator = map_cgal_simplex_tree.find(the_alpha_shape_vertex);
+ if (the_map_iterator == map_cgal_simplex_tree.end()) {
+ // alpha shape not found
+ Complex_vertex_handle vertex = map_cgal_simplex_tree.size();
+#ifdef DEBUG_TRACES
+ std::cout << "vertex [" << the_alpha_shape_vertex->point() << "] not found - insert " << vertex << std::endl;
+#endif // DEBUG_TRACES
+ the_simplex.push_back(vertex);
+ map_cgal_simplex_tree.emplace(the_alpha_shape_vertex, vertex);
+ } else {
+ // alpha shape found
+ Complex_vertex_handle vertex = the_map_iterator->second;
+#ifdef DEBUG_TRACES
+ std::cout << "vertex [" << the_alpha_shape_vertex->point() << "] found in " << vertex << std::endl;
+#endif // DEBUG_TRACES
+ the_simplex.push_back(vertex);
+ }
+ }
+ // Construction of the simplex_tree
+ Filtration_value filtr = Value_from_iterator<Complexity>::perform(alpha_value_iterator);
+
+#ifdef DEBUG_TRACES
+ std::cout << "filtration = " << filtr << std::endl;
+#endif // DEBUG_TRACES
+ complex.insert_simplex(the_simplex, static_cast<Filtration_value>(filtr));
+ GUDHI_CHECK(alpha_value_iterator != alpha_values.end(), "CGAL provided more simplices than values");
+ ++alpha_value_iterator;
+ }
+
+#ifdef DEBUG_TRACES
+ std::cout << "vertices \t" << count_vertices << std::endl;
+ std::cout << "edges \t\t" << count_edges << std::endl;
+ std::cout << "facets \t\t" << count_facets << std::endl;
+ std::cout << "cells \t\t" << count_cells << std::endl;
+#endif // DEBUG_TRACES
+ // --------------------------------------------------------------------------------------------
+ // As Alpha value is an approximation, we have to make filtration non decreasing while increasing the dimension
+ complex.make_filtration_non_decreasing();
+ // Remove all simplices that have a filtration value greater than max_alpha_square
+ complex.prune_above_filtration(max_alpha_square);
+ // --------------------------------------------------------------------------------------------
+ return true;
+ }
+
+ private:
+ // use of a unique_ptr on cgal Alpha_shape_3, as copy and default constructor is not available - no need to be freed
+ std::unique_ptr<Alpha_shape_3> alpha_shape_3_ptr_;
+};
+
+} // namespace alpha_complex
+
+} // namespace Gudhi
+
+#endif // ALPHA_COMPLEX_3D_H_
diff --git a/src/Alpha_complex/include/gudhi/Alpha_complex_options.h b/src/Alpha_complex/include/gudhi/Alpha_complex_options.h
new file mode 100644
index 00000000..85c83672
--- /dev/null
+++ b/src/Alpha_complex/include/gudhi/Alpha_complex_options.h
@@ -0,0 +1,33 @@
+/* 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): Vincent Rouvreau
+ *
+ * Copyright (C) 2018 Inria
+ *
+ * Modification(s):
+ * - YYYY/MM Author: Description of the modification
+ */
+
+#ifndef ALPHA_COMPLEX_OPTIONS_H_
+#define ALPHA_COMPLEX_OPTIONS_H_
+
+namespace Gudhi {
+
+namespace alpha_complex {
+
+/**
+ * \brief Alpha complex complexity template parameter possible values.
+ *
+ * \ingroup alpha_complex
+ */
+enum class complexity : char {
+ FAST = 'f', ///< Fast version.
+ SAFE = 's', ///< Safe version.
+ EXACT = 'e', ///< Exact version.
+};
+
+} // namespace alpha_complex
+
+} // namespace Gudhi
+
+#endif // ALPHA_COMPLEX_OPTIONS_H_