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

CGAL 4.8 - 2D Segment Delaunay Graphs

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Segment_Delaunay_graph_2/sdg-red-blue-info.cpp
#include <CGAL/Random.h>
// example that shows how to add info to input sites and how this is
// propagated using the storage traits with info
//
// the input sites are considered to be colored either red of blue;
// points on the plane belonging to sites of different colors become
// purple.
// standard includes
#include <iostream>
#include <fstream>
#include <cassert>
// an enum representing the color
enum Red_blue {
RED = 1,
BLUE = 2,
PURPLE = 3
};
// output operator for the color
std::ostream&
operator<<(std::ostream& os, const Red_blue& rb)
{
if ( rb == RED ) { os << "Red"; }
else if ( rb == BLUE ) { os << "Blue"; }
else if ( rb == PURPLE ) { os << "Purple"; }
return os;
}
// functor that defines how to convert color info when:
// 1. constructing the storage site of an endpoint of a segment
// 2. a segment site is split into two sub-segments
struct Red_blue_convert_info
{
typedef Red_blue Info;
typedef const Info& result_type;
inline
const Info& operator()(const Info& info0, bool) const {
// just return the info of the supporting segment
return info0;
}
inline
const Info& operator()(const Info& info0, const Info& , bool) const {
// just return the info of the supporting segment
return info0;
}
};
// functor that defines how to merge color info when a site (either
// point or segment) corresponds to point(s) on plane belonging to
// more than one input site
struct Red_blue_merge_info
{
typedef Red_blue Info;
typedef Info result_type;
inline
Info operator()(const Info& info0, const Info& info1) const {
// if the two sites defining the new site have the same info, keep
// this common info
if ( info0 == info1 ) { return info0; }
// otherwise the new site should be purple
return PURPLE;
}
};
// choose the kernel
#include <CGAL/Simple_cartesian.h>
// typedefs for the geometric traits, storage traits and the algorithm
#include <CGAL/Segment_Delaunay_graph_2.h>
#include <CGAL/Segment_Delaunay_graph_filtered_traits_2.h>
#include <CGAL/Segment_Delaunay_graph_storage_traits_with_info_2.h>
typedef CGAL::Simple_cartesian<double> K;
typedef CGAL::Segment_Delaunay_graph_filtered_traits_2<K> Gt;
// define the storage traits with info
typedef
CGAL::Segment_Delaunay_graph_storage_traits_with_info_2<Gt,
Red_blue,
Red_blue_convert_info,
Red_blue_merge_info>
ST;
typedef CGAL::Segment_Delaunay_graph_2<Gt,ST> SDG2;
typedef SDG2::Finite_vertices_iterator FVIT;
typedef SDG2::Site_2 Site_2;
int main()
{
std::ifstream ifs("data/sitesxx.rb.cin");
assert( ifs );
SDG2 sdg;
Site_2 site;
// read the sites and their info and insert them in the
// segment Delaunay graph; print them as you read them
std::cout << std::endl;
std::cout << "Input sites:" << std::endl;
std::cout << "------------" << std::endl;
while ( ifs >> site ) {
char c;
ifs >> c;
Red_blue info = (c == 'r') ? RED : BLUE;
std::cout << site << std::flush;
std::cout << "\r\t\t\t" << info << std::endl;
sdg.insert(site, info);
}
std::cout << std::endl;
// validate the segment Delaunay graph
assert( sdg.is_valid(true, 1) );
// print the sites of the segment Delaunay graph and their info
std::cout << std::endl << std::endl;
std::cout << "Output sites:" << std::endl;
std::cout << "-------------" << std::endl;
for (FVIT it = sdg.finite_vertices_begin();
it != sdg.finite_vertices_end(); ++it) {
std::cout << it->site() << std::flush;
std::cout << "\r\t\t\t" << it->storage_site().info() << std::endl;
}
std::cout << std::endl;
return 0;
}