\( \newcommand{\E}{\mathrm{E}} \) \( \newcommand{\A}{\mathrm{A}} \) \( \newcommand{\R}{\mathrm{R}} \) \( \newcommand{\N}{\mathrm{N}} \) \( \newcommand{\Q}{\mathrm{Q}} \) \( \newcommand{\Z}{\mathrm{Z}} \) \( \def\ccSum #1#2#3{ \sum_{#1}^{#2}{#3} } \def\ccProd #1#2#3{ \sum_{#1}^{#2}{#3} }\)
CGAL 4.8.1 - 2D Polyline Simplification
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Polyline_simplification_2/points_and_vertices.cpp
#include <iostream>
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Polygon_2.h>
#include <CGAL/Constrained_Delaunay_triangulation_2.h>
#include <CGAL/Constrained_triangulation_plus_2.h>
#include <CGAL/Polyline_simplification_2/simplify.h>
namespace PS = CGAL::Polyline_simplification_2;
typedef CGAL::Polygon_2<K> Polygon_2;
typedef PS::Vertex_base_2<K> Vb;
typedef CGAL::Triangulation_data_structure_2<Vb, Fb> TDS;
typedef CT::Point Point;
typedef CT::Constraint_id Constraint_id;
typedef CT::Constraint_iterator Constraint_iterator;
typedef CT::Vertices_in_constraint_iterator Vertices_in_constraint_iterator;
typedef CT::Points_in_constraint_iterator Points_in_constraint_iterator;
typedef PS::Stop_below_count_ratio_threshold Stop;
typedef PS::Squared_distance_cost Cost;
void print(const CT& ct, Constraint_id cid)
{
std::cout << "simplified polyline" <<std::endl;
for(Vertices_in_constraint_iterator vit =
ct.vertices_in_constraint_begin(cid);
vit != ct.vertices_in_constraint_end(cid);
++vit){
std::cout << (*vit)->point() << std::endl ;
}
std::cout << "original points" <<std::endl;
for(Points_in_constraint_iterator pit =
ct.points_in_constraint_begin(cid);
pit != ct.points_in_constraint_end(cid);
++pit){
std::cout << *pit << std::endl ;
}
}
int main()
{
const bool remove_points = false;
CT ct;
Polygon_2 P;
Constraint_id cid;
std::size_t largest = 0;
while(std::cin >> P){
Constraint_id cid2 = ct.insert_constraint(P);
if(P.size() > largest){
cid = cid2;
}
}
PS::simplify(ct, cid, Cost(), Stop(0.5), remove_points);
print(ct, cid);
PS::simplify(ct, cid, Cost(), Stop(0.5), remove_points);
ct.remove_points_without_corresponding_vertex(cid);
print(ct, cid);
return 0;
}