Frechet_distance/Frechet_DS_3.cpp

#include <CGAL/Frechet_distance.h>
#include <CGAL/Frechet_distance_traits_3.h>
#include <CGAL/Frechet_distance/Neighbor_search.h>
#include <CGAL/Simple_cartesian.h>
#include <CGAL/IO/WKT.h>
 
#include <ostream>
#include <fstream>
#include <filesystem>
 
using Kernel = CGAL::Simple_cartesian<double>;
using Traits = CGAL::Frechet_distance_traits_3<Kernel>;
using Point = Traits::Point_d;
using Curve = std::vector<Point>;
using Curves = std::vector<Curve>;
 
int main()
{
 
  Curves curves;
  const std::filesystem::path data{"./data_3d"};
  for (auto const& dir_entry : std::filesystem::directory_iterator{data}){
    std::ifstream in(dir_entry.path());
    curves.push_back(Curve());
    CGAL::IO::read_linestring_WKT(in, curves.back());
  }
 
  Curve query = curves.back();
  curves.pop_back();
 
  CGAL::Frechet_distance::Neighbor_search<Curve, Traits> ds(curves);
 
  for(const Curve& c : curves){
    std::pair<double, double> res = CGAL::bounded_error_Frechet_distance(c, query, 0.000001);
    std::cout << "The Frechet distance between the polylines is between " <<  res.first << " and " << res.second << std::endl;
  }
  double distance = 16;
  std::vector<std::size_t> result = ds.get_close_curves(query, distance);
 
  std::cout << result.size() << " curves at Frechet distance closer than " << distance << std::endl;
  return 0;
}