128 lines
3.5 KiB
C++
128 lines
3.5 KiB
C++
// Copyright (c) 1998
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// Utrecht University (The Netherlands),
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// ETH Zurich (Switzerland),
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// INRIA Sophia-Antipolis (France),
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// Max-Planck-Institute Saarbruecken (Germany),
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// and Tel-Aviv University (Israel). All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org)
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//
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// $URL: https://github.com/CGAL/cgal/blob/v5.1/Generator/include/CGAL/random_convex_set_2.h $
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// $Id: random_convex_set_2.h 0779373 2020-03-26T13:31:46+01:00 Sébastien Loriot
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// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
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//
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//
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// Author(s) : Michael Hoffmann <hoffmann@inf.ethz.ch>
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#ifndef CGAL_RANDOM_CONVEX_SET_2_H
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#define CGAL_RANDOM_CONVEX_SET_2_H 1
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#include <CGAL/basic.h>
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#include <CGAL/algorithm.h>
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#include <vector>
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#include <algorithm>
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#include <numeric>
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#include <CGAL/Random_convex_set_traits_2.h>
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#include <boost/functional.hpp>
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namespace CGAL {
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template < class OutputIterator, class Point_generator, class Traits >
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OutputIterator
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random_convex_set_2( std::size_t n,
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OutputIterator o,
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const Point_generator& pg,
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Traits t)
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{
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CGAL_precondition( n >= 3);
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using std::vector;
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using std::back_inserter;
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using std::accumulate;
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using std::transform;
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using std::sort;
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using std::partial_sum;
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using std::less;
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using std::max_element;
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using std::copy_n;
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typedef typename Traits::Point_2 Point_2;
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typedef typename Traits::FT FT;
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typedef vector< Point_2 > Container;
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typedef typename Traits::Sum Sum;
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typedef typename Traits::Scale Scale;
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typedef typename Traits::Angle_less Angle_less;
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typedef typename Traits::Max_coordinate Max_coordinate;
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// GCC 2.8 and egcs-1.0.1 require these:
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// (does not accept s.l. Scale()( p, 1))
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Scale scale;
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Max_coordinate max_coordinate;
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Sum sum;
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// build random point set:
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Container points;
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points.reserve( n);
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std::copy_n( pg, n, back_inserter( points));
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// compute centroid of points:
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// Point_2 centroid = CGAL::centroid( points.begin(), points.end(), t );
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Point_2 centroid = t.origin();
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for(const Point_2& p : points){
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centroid = sum(centroid, p);
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}
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centroid = scale(centroid, FT(1)/FT(n));
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// translate s.t. centroid == origin:
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transform(
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points.begin(),
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points.end(),
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points.begin(),
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boost::bind2nd( Sum(), scale( centroid, FT( -1))));
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// sort them according to their direction's angle
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// w.r.t. the positive x-axis:
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sort( points.begin(), points.end(), Angle_less());
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// construct polygon:
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partial_sum(
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points.begin(), points.end(), points.begin(), Sum());
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// and compute its centroid:
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Point_2 new_centroid = t.origin();
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for(const Point_2& p : points){
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new_centroid = sum(new_centroid, p);
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}
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new_centroid = scale(new_centroid, FT(1)/FT(n));
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// translate s.t. centroids match:
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transform(
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points.begin(),
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points.end(),
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points.begin(),
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boost::bind2nd( Sum(), sum( centroid,
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scale( new_centroid, FT( -1)))));
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// compute maximal coordinate:
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FT maxcoord( max_coordinate(
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*max_element( points.begin(),
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points.end(),
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compose2_2( less< FT >(),
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Max_coordinate(),
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Max_coordinate()))));
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// and finally scale to fit into original grid:
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return transform(
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points.begin(),
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points.end(),
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o,
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boost::bind2nd( Scale(), FT( pg.range()) / maxcoord));
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} // random_convex_set_2( n, o, pg, t)
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} //namespace CGAL
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#endif // ! (CGAL_RANDOM_CONVEX_SET_2_H)
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