\( \newcommand{\E}{\mathrm{E}} \) \( \newcommand{\A}{\mathrm{A}} \) \( \newcommand{\R}{\mathrm{R}} \) \( \newcommand{\N}{\mathrm{N}} \) \( \newcommand{\Q}{\mathrm{Q}} \) \( \newcommand{\Z}{\mathrm{Z}} \) \( \def\ccSum #1#2#3{ \sum_{#1}^{#2}{#3} } \def\ccProd #1#2#3{ \sum_{#1}^{#2}{#3} }\)
CGAL 5.0.1 - Shape Detection
Shape_detection/region_growing_on_polygon_mesh.cpp
// STL includes.
#include <string>
#include <vector>
#include <cstdlib>
#include <fstream>
#include <iostream>
#include <iterator>
// CGAL includes.
#include <CGAL/memory.h>
#include <CGAL/IO/Color.h>
#include <CGAL/Iterator_range.h>
#include <CGAL/HalfedgeDS_vector.h>
#include <CGAL/Exact_predicates_exact_constructions_kernel.h>
#include <CGAL/Surface_mesh.h>
#include <CGAL/Polyhedron_3.h>
#include <CGAL/Shape_detection/Region_growing/Region_growing.h>
#include <CGAL/Shape_detection/Region_growing/Region_growing_on_polygon_mesh.h>
// Type declarations.
using FT = typename Kernel::FT;
using Point_3 = typename Kernel::Point_3;
using Color = CGAL::Color;
// Choose the type of a container for a polygon mesh.
#define USE_SURFACE_MESH
#if defined(USE_SURFACE_MESH)
using Polygon_mesh = CGAL::Surface_mesh<Point_3>;
using Face_range = typename Polygon_mesh::Face_range;
#else
#endif
using Region = std::vector<std::size_t>;
using Regions = std::vector<Region>;
using Vertex_to_point_map = typename Region_type::Vertex_to_point_map;
int main(int argc, char *argv[]) {
std::cout << std::endl <<
"region_growing_on_polygon_mesh example started"
<< std::endl << std::endl;
// Load off data either from a local folder or a user-provided file.
std::ifstream in(argc > 1 ? argv[1] : "data/polygon_mesh.off");
Polygon_mesh polygon_mesh;
in >> polygon_mesh;
in.close();
const Face_range face_range = faces(polygon_mesh);
std::cout <<
"* polygon mesh with "
<< face_range.size() <<
" faces is loaded"
<< std::endl;
// Default parameter values for the data file polygon_mesh.off.
const FT max_distance_to_plane = FT(1);
const FT max_accepted_angle = FT(45);
const std::size_t min_region_size = 5;
// Create instances of the classes Neighbor_query and Region_type.
Neighbor_query neighbor_query(polygon_mesh);
const Vertex_to_point_map vertex_to_point_map(
get(CGAL::vertex_point, polygon_mesh));
Region_type region_type(
polygon_mesh,
max_distance_to_plane, max_accepted_angle, min_region_size,
vertex_to_point_map);
// Sort face indices.
Sorting sorting(
polygon_mesh, neighbor_query,
vertex_to_point_map);
sorting.sort();
// Create an instance of the region growing class.
Region_growing region_growing(
face_range, neighbor_query, region_type,
sorting.seed_map());
// Run the algorithm.
Regions regions;
region_growing.detect(std::back_inserter(regions));
// Print the number of found regions.
std::cout << "* " << regions.size() <<
" regions have been found"
<< std::endl;
// Save the result in a file only if it is stored in CGAL::Surface_mesh.
#if defined(USE_SURFACE_MESH)
using Face_index = typename Polygon_mesh::Face_index;
// Save the result to a file in the user-provided path if any.
srand(static_cast<unsigned int>(time(NULL)));
if (argc > 2) {
bool created;
typename Polygon_mesh::template Property_map<Face_index, Color> face_color;
boost::tie(face_color, created) =
polygon_mesh.template add_property_map<Face_index, Color>(
"f:color", Color(0, 0, 0));
if (!created) {
std::cout << std::endl <<
"region_growing_on_polygon_mesh example finished"
<< std::endl << std::endl;
return EXIT_FAILURE;
}
const std::string path = argv[2];
const std::string fullpath = path + "regions_polygon_mesh.off";
std::ofstream out(fullpath);
// Iterate through all regions.
for (const auto& region : regions) {
// Generate a random color.
const Color color(
static_cast<unsigned char>(rand() % 256),
static_cast<unsigned char>(rand() % 256),
static_cast<unsigned char>(rand() % 256));
// Iterate through all region items.
using size_type = typename Polygon_mesh::size_type;
for (const auto index : region)
face_color[Face_index(static_cast<size_type>(index))] = color;
}
out << polygon_mesh;
out.close();
std::cout <<
"* polygon mesh is saved in "
<< fullpath << std::endl;
}
#endif
std::cout << std::endl <<
"region_growing_on_polygon_mesh example finished"
<< std::endl << std::endl;
return EXIT_SUCCESS;
}