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// Copyright (c) 2000
// Utrecht University (The Netherlands),
// ETH Zurich (Switzerland),
// INRIA Sophia-Antipolis (France),
// Max-Planck-Institute Saarbruecken (Germany),
// and Tel-Aviv University (Israel). All rights reserved.
//
// This file is part of CGAL (www.cgal.org)
//
// $URL: https://github.com/CGAL/cgal/blob/v6.1.1/Generator/include/CGAL/random_polygon_2.h $
// $Id: include/CGAL/random_polygon_2.h 08b27d3db14 $
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
//
// Author(s) : Susan Hert <hert@mpi-sb.mpg.de>
#ifndef CGAL_RANDOM_POLYGON_2_H
#define CGAL_RANDOM_POLYGON_2_H
#include <list>
#include <set>
#include <vector>
#include <CGAL/algorithm.h>
#include <CGAL/Random_polygon_2_sweep.h>
#include <CGAL/Kernel_traits.h>
namespace CGAL {
//
// Using the provided point generator, generates a set of n points and
// produces a simple polygon from the unique subset of points within this
// set.
//
// Each of the p possible simple polygons for the unique point set is
// generated with probability greater than 0 but the polygons are not
// generated with uniform probability.
//
template <class PointGenerator, class OutputIterator, class Traits>
OutputIterator random_polygon_2(std::size_t n, OutputIterator result,
const PointGenerator& pg, const Traits& traits)
{
typedef typename Traits::Point_2 Point_2;
typedef std::vector<Point_2> Vertex_list;
Vertex_list vertices;
copy_n_unique(pg, n, std::back_inserter(vertices), traits);
CGAL_assertion(!duplicate_points(vertices.begin(), vertices.end(), traits));
CGAL_precondition_code(auto d = std::distance(vertices.begin(), vertices.end());)
CGAL_precondition(d > 2);
CGAL_precondition_code(const Point_2& p = *(vertices.begin());)
CGAL_precondition_code(const Point_2& q = *(std::next(vertices.begin()));)
CGAL_precondition_code(auto third_it = std::next(vertices.begin(), 2);)
CGAL_precondition_code(bool all_collinear = true;)
CGAL_precondition_code(do {)
CGAL_precondition_code( if(traits.orientation_2_object()(p, q, *third_it) != CGAL::COLLINEAR) {)
CGAL_precondition_code( all_collinear = false;)
CGAL_precondition_code( break;)
CGAL_precondition_code( })
CGAL_precondition_code(} while(++third_it != vertices.end());)
CGAL_precondition(!all_collinear);
#ifndef CGAL_DONT_SHUFFLE_IN_RANDOM_POLYGON_2
CGAL::cpp98::random_shuffle(vertices.begin(), vertices.end());
#endif
make_simple_polygon(vertices.begin(), vertices.end(), traits);
if (orientation_2(vertices.begin(), vertices.end()) == CLOCKWISE)
std::reverse(vertices.begin(), vertices.end());
CGAL_assertion(is_simple_2(vertices.begin(), vertices.end()));
return std::copy(vertices.begin(), vertices.end(), result);
}
template <class PointGenerator, class OutputIterator>
inline
OutputIterator random_polygon_2( std::size_t n, OutputIterator result,
const PointGenerator& pg )
{
typedef typename std::iterator_traits<PointGenerator>::value_type Point_2;
typedef typename Kernel_traits<Point_2>::Kernel K;
return random_polygon_2(n, result, pg, K());
}
template <class ForwardIterator, class Traits>
bool duplicate_points(ForwardIterator first, ForwardIterator beyond,
const Traits& )
{
typedef typename Traits::Point_2 Point_2;
typedef typename Traits::Less_xy_2 Less_xy_2;
std::set<Point_2,Less_xy_2> point_set;
for (; first != beyond; first++)
if (!(point_set.insert(*first)).second) return true;
return false;
}
template <class ForwardIterator>
bool duplicate_points(ForwardIterator first, ForwardIterator beyond)
{
typedef typename std::iterator_traits<ForwardIterator>::value_type Point_2;
typedef typename Kernel_traits<Point_2>::Kernel K;
return duplicate_points(first, beyond, K());
}
// Copies the first n points from the input iterator to the output iterator,
// removing any duplicates. Thus fewer than n points may be inserted into
// the output iterator.
template <class InputIterator, class Size, class OutputIterator, class Traits>
OutputIterator copy_n_unique(InputIterator first, Size n,
OutputIterator result,
const Traits& )
{
typedef typename Traits::Point_2 Point_2;
typedef typename Traits::Less_xy_2 Less_xy_2;
std::set<Point_2, Less_xy_2> sorted_point_set;
for (Size i = 0; i < n; i++)
{
if (sorted_point_set.insert(*first).second)
{
*result = *first;
result++;
}
first++;
}
return result;
}
template <class InputIterator, class Size, class OutputIterator>
inline
OutputIterator copy_n_unique(InputIterator first, Size n,
OutputIterator result)
{
typedef typename std::iterator_traits<InputIterator>::value_type Point_2;
typedef typename Kernel_traits<Point_2>::Kernel K;
return copy_n_unique(first, n, result, K());
}
} // namespace CGAL
#endif
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