\( \newcommand{\E}{\mathrm{E}} \) \( \newcommand{\A}{\mathrm{A}} \) \( \newcommand{\R}{\mathrm{R}} \) \( \newcommand{\N}{\mathrm{N}} \) \( \newcommand{\Q}{\mathrm{Q}} \) \( \newcommand{\Z}{\mathrm{Z}} \) \( \def\ccSum #1#2#3{ \sum_{#1}^{#2}{#3} } \def\ccProd #1#2#3{ \sum_{#1}^{#2}{#3} }\)

CGAL 4.8 - 2D Arrangements

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Arrangement_on_surface_2/predefined_kernel.cpp
// Constructing an arrangements of intersecting line segments using the
// predefined kernel with exact constructions and exact predicates.
#include <CGAL/Exact_predicates_exact_constructions_kernel.h>
#include <CGAL/Arr_segment_traits_2.h>
#include <CGAL/Arrangement_2.h>
#include <CGAL/Timer.h>
#include <list>
#include <fstream>
typedef CGAL::Exact_predicates_exact_constructions_kernel Kernel;
typedef Kernel::FT Number_type;
typedef CGAL::Arr_segment_traits_2<Kernel> Traits_2;
typedef Traits_2::Point_2 Point_2;
typedef Traits_2::X_monotone_curve_2 Segment_2;
typedef CGAL::Arrangement_2<Traits_2> Arrangement_2;
int main (int argc, char *argv[])
{
// Get the name of the input file from the command line, or use the default
// fan_grids.dat file if no command-line parameters are given.
const char * filename = (argc > 1) ? argv[1] : "fan_grids.dat";
// Open the input file.
std::ifstream in_file (filename);
if (! in_file.is_open()) {
std::cerr << "Failed to open " << filename << " ..." << std::endl;
return (1);
}
// Read the segments from the file.
// The input file format should be (all coordinate values are integers):
// <n> // number of segments.
// <sx_1> <sy_1> <tx_1> <ty_1> // source and target of segment #1.
// <sx_2> <sy_2> <tx_2> <ty_2> // source and target of segment #2.
// : : : :
// <sx_n> <sy_n> <tx_n> <ty_n> // source and target of segment #n.
std::list<Segment_2> segments;
unsigned int n;
in_file >> n;
unsigned int i;
for (i = 0; i < n; ++i) {
int sx, sy, tx, ty;
in_file >> sx >> sy >> tx >> ty;
segments.push_back (Segment_2 (Point_2 (Number_type(sx), Number_type(sy)),
Point_2 (Number_type(tx), Number_type(ty))));
}
in_file.close();
// Construct the arrangement by aggregately inserting all segments.
Arrangement_2 arr;
CGAL::Timer timer;
std::cout << "Performing aggregated insertion of "
<< n << " segments." << std::endl;
timer.start();
insert (arr, segments.begin(), segments.end());
timer.stop();
// Print the arrangement dimensions.
std::cout << "V = " << arr.number_of_vertices()
<< ", E = " << arr.number_of_edges()
<< ", F = " << arr.number_of_faces() << std::endl;
std::cout << "Construction took " << timer.time()
<< " seconds." << std::endl;
return 0;
}