CGAL 5.6.1 - 2D Straight Skeleton and Polygon Offsetting
Straight_skeleton_2/Show_offset_polygon.cpp
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Polygon_with_holes_2.h>
#include <CGAL/create_offset_polygons_from_polygon_with_holes_2.h>
#include "dump_to_eps.h"
#include <boost/shared_ptr.hpp>
#include <cassert>
#include <fstream>
#include <iostream>
#include <string>
#include <vector>
typedef CGAL::Polygon_with_holes_2<K> Polygon_with_holes ;
typedef boost::shared_ptr<Polygon_with_holes> Polygon_with_holes_ptr ;
typedef std::vector<Polygon_with_holes_ptr> Polygon_with_holes_ptr_vector ;
int main( int argc, char* argv[] )
{
Polygon_with_holes input ;
if ( argc > 1 )
{
std::string name = argv[1] ;
std::cout << "Input file: " << name << std::endl ;
std::ifstream is(name.c_str()) ;
if ( is )
{
is >> input ;
assert(input.outer_boundary().is_counterclockwise_oriented());
for(Polygon_with_holes::Hole_const_iterator it = input.holes_begin();
it != input.holes_end();
++it){
assert(it->is_clockwise_oriented());
}
double lOffset = 0.25 ;
if ( argc > 2 )
lOffset = std::atof(argv[2]);
std::cout << "Offsetting at: " << lOffset << std::endl ;
Polygon_with_holes_ptr_vector offset_polygons = CGAL::create_interior_skeleton_and_offset_polygons_with_holes_2(lOffset,input);
std::string eps_name ;
if ( argc > 3 )
eps_name = argv[3];
else eps_name = name + ".offset.eps" ;
std::ofstream eps(eps_name.c_str()) ;
if ( eps )
{
std::cerr << "Result: " << eps_name << std::endl ;
dump_to_eps(input,offset_polygons,eps);
}
else
{
std::cerr << "Could not open result file: " << eps_name << std::endl ;
}
}
else
{
std::cerr << "Could not open input file: " << name << std::endl ;
}
}
else
{
std::cerr << "Computes the interior offset of a polygon with holes and draws the result in an EPS file." << std::endl
<< std::endl
<< "Usage: show_offset_polygon <input_file> [output_eps_file]" << std::endl
<< std::endl
<< " input_file Text file describing the input polygon with holes." << std::endl
<< " (See input_file_format.txt for details" << std::endl
<< " or use input_file_example.txt)" << std::endl
<< " output_file [default='input_file.offset.eps']" << std::endl ;
}
return 0;
}