1 files changed, 264 insertions, 0 deletions
diff --git a/src/Simplex_tree/example/example_alpha_shapes_3_simplex_tree_from_off_file.cpp b/src/Simplex_tree/example/example_alpha_shapes_3_simplex_tree_from_off_file.cpp
new file mode 100644
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--- /dev/null
+++ b/src/Simplex_tree/example/example_alpha_shapes_3_simplex_tree_from_off_file.cpp
@@ -0,0 +1,264 @@
+/*    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) 2014 Inria
+ *
+ *    Modification(s):
+ *      - YYYY/MM Author: Description of the modification
+ */
+
+#include <gudhi/Simplex_tree.h>
+#include <gudhi/Points_3D_off_io.h>
+
+#include <boost/variant.hpp>
+
+#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
+#include <CGAL/Delaunay_triangulation_3.h>
+#include <CGAL/Alpha_shape_3.h>
+#include <CGAL/Alpha_shape_vertex_base_3.h>
+#include <CGAL/Alpha_shape_cell_base_3.h>
+#include <CGAL/iterator.h>
+
+#include <fstream>
+#include <cmath>
+#include <string>
+#include <tuple>  // for tuple<>
+#include <map>
+#include <utility>  // for pair<>
+#include <list>
+#include <vector>
+
+// Alpha_shape_3 templates type definitions
+typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
+typedef CGAL::Alpha_shape_vertex_base_3<Kernel> Vb;
+typedef CGAL::Alpha_shape_cell_base_3<Kernel> Fb;
+typedef CGAL::Triangulation_data_structure_3<Vb, Fb> Tds;
+typedef CGAL::Delaunay_triangulation_3<Kernel, Tds> Triangulation_3;
+typedef CGAL::Alpha_shape_3<Triangulation_3> Alpha_shape_3;
+
+// From file type definition
+typedef Kernel::Point_3 Point;
+
+// filtration with alpha values needed type definition
+typedef Alpha_shape_3::FT Alpha_value_type;
+typedef CGAL::Object Object;
+typedef CGAL::Dispatch_output_iterator<
+CGAL::cpp11::tuple<Object, Alpha_value_type>,
+CGAL::cpp11::tuple<std::back_insert_iterator< std::vector<Object> >,
+    std::back_insert_iterator< std::vector<Alpha_value_type> > > > Dispatch;
+typedef Alpha_shape_3::Cell_handle Cell_handle;
+typedef Alpha_shape_3::Facet Facet;
+typedef Alpha_shape_3::Edge Edge;
+typedef std::list<Alpha_shape_3::Vertex_handle> Vertex_list;
+
+// gudhi type definition
+typedef Gudhi::Simplex_tree<> Simplex_tree;
+typedef Simplex_tree::Vertex_handle Simplex_tree_vertex;
+typedef std::map<Alpha_shape_3::Vertex_handle, Simplex_tree_vertex > Alpha_shape_simplex_tree_map;
+typedef std::pair<Alpha_shape_3::Vertex_handle, Simplex_tree_vertex> Alpha_shape_simplex_tree_pair;
+typedef std::vector< Simplex_tree_vertex > Simplex_tree_vector_vertex;
+
+Vertex_list from(const Cell_handle& ch) {
+  Vertex_list the_list;
+  for (auto i = 0; i < 4; i++) {
+#ifdef DEBUG_TRACES
+    std::cout << "from cell[" << i << "]=" << ch->vertex(i)->point() << std::endl;
+#endif  // DEBUG_TRACES
+    the_list.push_back(ch->vertex(i));
+  }
+  return the_list;
+}
+
+Vertex_list from(const Facet& fct) {
+  Vertex_list the_list;
+  for (auto i = 0; i < 4; i++) {
+    if (fct.second != i) {
+#ifdef DEBUG_TRACES
+      std::cout << "from facet=[" << i << "]" << fct.first->vertex(i)->point() << std::endl;
+#endif  // DEBUG_TRACES
+      the_list.push_back(fct.first->vertex(i));
+    }
+  }
+  return the_list;
+}
+
+Vertex_list from(const Edge& edg) {
+  Vertex_list the_list;
+  for (auto i = 0; i < 4; i++) {
+    if ((edg.second == i) || (edg.third == i)) {
+#ifdef DEBUG_TRACES
+      std::cout << "from edge[" << i << "]=" << edg.first->vertex(i)->point() << std::endl;
+#endif  // DEBUG_TRACES
+      the_list.push_back(edg.first->vertex(i));
+    }
+  }
+  return the_list;
+}
+
+Vertex_list from(const Alpha_shape_3::Vertex_handle& vh) {
+  Vertex_list the_list;
+#ifdef DEBUG_TRACES
+  std::cout << "from vertex=" << vh->point() << std::endl;
+#endif  // DEBUG_TRACES
+  the_list.push_back(vh);
+  return the_list;
+}
+
+int main(int argc, char * const argv[]) {
+  // program args management
+  if (argc != 2) {
+    std::cerr << "Usage: " << argv[0]
+        << " path_to_off_file \n";
+    return 0;
+  }
+
+  // Read points from file
+  std::string offInputFile(argv[1]);
+  // Read the OFF file (input file name given as parameter) and triangulate points
+  Gudhi::Points_3D_off_reader<Point> off_reader(offInputFile);
+  // Check the read operation was correct
+  if (!off_reader.is_valid()) {
+    std::cerr << "Unable to read file " << argv[1] << std::endl;
+    return 0;
+  }
+  // Retrieve the triangulation
+  std::vector<Point> lp = off_reader.get_point_cloud();
+
+  // alpha shape construction from points. CGAL has a strange behavior in REGULARIZED mode.
+  Alpha_shape_3 as(lp.begin(), lp.end(), 0, Alpha_shape_3::GENERAL);
+#ifdef DEBUG_TRACES
+  std::cout << "Alpha shape computed in GENERAL mode" << std::endl;
+#endif  // DEBUG_TRACES
+
+  // filtration with alpha values from alpha shape
+  std::vector<Object> the_objects;
+  std::vector<Alpha_value_type> the_alpha_values;
+
+  Dispatch disp = CGAL::dispatch_output<Object, Alpha_value_type>(std::back_inserter(the_objects),
+      std::back_inserter(the_alpha_values));
+
+  as.filtration_with_alpha_values(disp);
+#ifdef DEBUG_TRACES
+  std::cout << "filtration_with_alpha_values returns : " << the_objects.size() << " objects" << std::endl;
+#endif  // DEBUG_TRACES
+
+  Alpha_shape_3::size_type count_vertices = 0;
+  Alpha_shape_3::size_type count_edges = 0;
+  Alpha_shape_3::size_type count_facets = 0;
+  Alpha_shape_3::size_type count_cells = 0;
+
+  // Loop on objects vector
+  Vertex_list vertex_list;
+  Simplex_tree simplex_tree;
+  Alpha_shape_simplex_tree_map map_cgal_simplex_tree;
+  std::vector<Alpha_value_type>::iterator the_alpha_value_iterator = the_alpha_values.begin();
+  for (auto object_iterator : the_objects) {
+    // Retrieve Alpha shape vertex list from object
+    if (const Cell_handle * cell = CGAL::object_cast<Cell_handle>(&object_iterator)) {
+      vertex_list = from(*cell);
+      count_cells++;
+    } else if (const Facet * facet = CGAL::object_cast<Facet>(&object_iterator)) {
+      vertex_list = from(*facet);
+      count_facets++;
+    } else if (const Edge * edge = CGAL::object_cast<Edge>(&object_iterator)) {
+      vertex_list = from(*edge);
+      count_edges++;
+    } else if (const Alpha_shape_3::Vertex_handle * vertex =
+              CGAL::object_cast<Alpha_shape_3::Vertex_handle>(&object_iterator)) {
+      count_vertices++;
+      vertex_list = from(*vertex);
+    }
+    // Construction of the vector of simplex_tree vertex from list of alpha_shapes vertex
+    Simplex_tree_vector_vertex the_simplex_tree;
+    for (auto the_alpha_shape_vertex : vertex_list) {
+      Alpha_shape_simplex_tree_map::iterator 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
+        Simplex_tree_vertex vertex = map_cgal_simplex_tree.size();
+#ifdef DEBUG_TRACES
+        std::cout << "vertex [" << the_alpha_shape_vertex->point() << "] not found - insert_simplex " << vertex << "\n";
+#endif  // DEBUG_TRACES
+        the_simplex_tree.push_back(vertex);
+        map_cgal_simplex_tree.insert(Alpha_shape_simplex_tree_pair(the_alpha_shape_vertex, vertex));
+      } else {
+        // alpha shape found
+        Simplex_tree_vertex 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_tree.push_back(vertex);
+      }
+    }
+    // Construction of the simplex_tree
+#ifdef DEBUG_TRACES
+    std::cout << "filtration = " << *the_alpha_value_iterator << std::endl;
+#endif  // DEBUG_TRACES
+    simplex_tree.insert_simplex(the_simplex_tree, std::sqrt(*the_alpha_value_iterator));
+    if (the_alpha_value_iterator != the_alpha_values.end())
+      ++the_alpha_value_iterator;
+    else
+      std::cerr << "This shall not happen" << std::endl;
+  }
+#ifdef DEBUG_TRACES
+  std::cout << "vertices \t\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;
+
+
+  std::cout << "Information of the Simplex Tree:\n";
+  std::cout << "  Number of vertices = " << simplex_tree.num_vertices() << " ";
+  std::cout << "  Number of simplices = " << simplex_tree.num_simplices() << std::endl << std::endl;
+#endif  // DEBUG_TRACES
+
+#ifdef DEBUG_TRACES
+  std::cout << "Iterator on vertices: \n";
+  for (auto vertex : simplex_tree.complex_vertex_range()) {
+    std::cout << vertex << " ";
+  }
+#endif  // DEBUG_TRACES
+
+  std::cout << simplex_tree << std::endl;
+
+#ifdef DEBUG_TRACES
+  std::cout << std::endl << std::endl << "Iterator on simplices:\n";
+  for (auto simplex : simplex_tree.complex_simplex_range()) {
+    std::cout << "   ";
+    for (auto vertex : simplex_tree.simplex_vertex_range(simplex)) {
+      std::cout << vertex << " ";
+    }
+    std::cout << std::endl;
+  }
+#endif  // DEBUG_TRACES
+#ifdef DEBUG_TRACES
+  std::cout << std::endl << std::endl << "Iterator on Simplices in the filtration, with [filtration value]:\n";
+  for (auto f_simplex : simplex_tree.filtration_simplex_range()) {
+    std::cout << "   " << "[" << simplex_tree.filtration(f_simplex) << "] ";
+    for (auto vertex : simplex_tree.simplex_vertex_range(f_simplex)) {
+      std::cout << vertex << " ";
+    }
+    std::cout << std::endl;
+  }
+#endif  // DEBUG_TRACES
+#ifdef DEBUG_TRACES
+  std::cout << std::endl << std::endl << "Iterator on Simplices in the filtration, and their boundary simplices:\n";
+  for (auto f_simplex : simplex_tree.filtration_simplex_range()) {
+    std::cout << "   " << "[" << simplex_tree.filtration(f_simplex) << "] ";
+    for (auto vertex : simplex_tree.simplex_vertex_range(f_simplex)) {
+      std::cout << vertex << " ";
+    }
+    std::cout << std::endl;
+
+    for (auto b_simplex : simplex_tree.boundary_simplex_range(f_simplex)) {
+      std::cout << "      " << "[" << simplex_tree.filtration(b_simplex) << "] ";
+      for (auto vertex : simplex_tree.simplex_vertex_range(b_simplex)) {
+        std::cout << vertex << " ";
+      }
+      std::cout << std::endl;
+    }
+  }
+#endif  // DEBUG_TRACES
+
+  return 0;
+}