\( \newcommand{\E}{\mathrm{E}} \) \( \newcommand{\A}{\mathrm{A}} \) \( \newcommand{\R}{\mathrm{R}} \) \( \newcommand{\N}{\mathrm{N}} \) \( \newcommand{\Q}{\mathrm{Q}} \) \( \newcommand{\Z}{\mathrm{Z}} \) \( \def\ccSum #1#2#3{ \sum_{#1}^{#2}{#3} } \def\ccProd #1#2#3{ \sum_{#1}^{#2}{#3} }\)
CGAL 4.14.2 - 3D Convex Hulls
Convex_hull_3/extreme_indices_3.cpp
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/convex_hull_3.h>
#include <CGAL/Extreme_points_traits_adapter_3.h>
#include <CGAL/IO/read_off_points.h>
#include <boost/iterator/counting_iterator.hpp>
#include <vector>
#include <fstream>
typedef K::Point_3 Point_3;
int main(int argc, char* argv[])
{
std::ifstream in( (argc>1)? argv[1] : "data/star.off");
if(!in)
{
std::cerr<< "Cannot open input file." <<std::endl;
return 1;
}
std::vector<Point_3> points;
CGAL::read_off_points(in, std::back_inserter(points));
//This will contain the extreme vertices
std::vector<std::size_t> extreme_point_indices;
//call the function with the traits adapter for vertices
CGAL::extreme_points_3(CGAL::make_range(boost::counting_iterator<std::size_t>(0),
boost::counting_iterator<std::size_t>(points.size())),
std::back_inserter(extreme_point_indices),
CGAL::make_extreme_points_traits_adapter(CGAL::make_property_map(points)));
//print the number of extreme vertices
std::cout << "Indices of points on the convex hull are:\n";
std::copy(extreme_point_indices.begin(), extreme_point_indices.end(), std::ostream_iterator<std::size_t>(std::cout, " "));
std::cout << "\n";
return 0;
}