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// Copyright (c) 2010 INRIA Sophia-Antipolis (France).
// 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/point_generators_d.h $
// $Id: include/CGAL/point_generators_d.h 08b27d3db14 $
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
//
// Author(s) : Olivier Devillers
#ifndef CGAL_POINT_GENERATORS_D_H
#define CGAL_POINT_GENERATORS_D_H 1
#include <CGAL/disable_warnings.h>
#include <CGAL/generators.h>
#include <CGAL/number_type_basic.h>
#include <CGAL/number_type_config.h>
#include <cmath>
#include <vector>
namespace CGAL {
template < class P >
class Random_points_in_ball_d : public Random_generator_base<P>{
void generate_point();
int dimension;
public:
typedef Random_points_in_ball_d<P> This;
Random_points_in_ball_d( int dim, double a = 1,
Random& rnd = get_default_random())
// g is an input iterator creating points of type `P' uniformly
// distributed in the open sphere with radius r, i.e. |`*g'| < r .
: Random_generator_base<P>( a, rnd), dimension(dim) { generate_point(); }
This& operator++() {
generate_point();
return *this;
}
This operator++(int) {
This tmp = *this;
++(*this);
return tmp;
}
};
template < class P >
void
Random_points_in_ball_d<P>::
generate_point() {
double norm = 0;
std::vector< double > coord(dimension);
for(int i=0; i<dimension; ++i) {
// normal distribution
//( a product of normal distib is a normal distrib in higher dim)
double a=this->_rnd.get_double();
a = std::sqrt( -2* std::log(1-a) );
double b=this->_rnd.get_double();
b = std::cos(2*CGAL_PI*b);
coord[i]= a*b;
norm += coord[i]*coord[i];
}
norm = this->d_range * std::pow(this->_rnd.get_double(),1.0/dimension)
/std::sqrt(norm);
for(int i=0; i<dimension; ++i) coord[i] *= norm;
this->d_item = P(dimension, coord.begin(), coord.end() );
}
template < class P >
class Random_points_on_sphere_d : public Random_generator_base<P>{
void generate_point();
int dimension;
public:
typedef Random_points_on_sphere_d<P> This;
Random_points_on_sphere_d( int dim, double a = 1,
Random& rnd = get_default_random())
// g is an input iterator creating points of type `P' uniformly
// distributed on the sphere with radius r, i.e. |`*g'| == r .
: Random_generator_base<P>( a, rnd), dimension(dim) { generate_point(); }
This& operator++() {
generate_point();
return *this;
}
This operator++(int) {
This tmp = *this;
++(*this);
return tmp;
}
};
template < class P >
void
Random_points_on_sphere_d<P>::
generate_point() {
double norm = 0;
std::vector< double > coord(dimension);
for(int i=0; i<dimension; ++i) {
// normal distribution
double a=this->_rnd.get_double();
a = std::sqrt( -2* std::log(1-a) );
double b=this->_rnd.get_double();
b = std::cos(2*CGAL_PI*b);
coord[i]= a*b;
norm += coord[i]*coord[i];
}
norm = this->d_range /std::sqrt(norm);
for(int i=0; i<dimension; ++i) coord[i] *= norm;
this->d_item = P(dimension, coord.begin(), coord.end() );
}
template < class P >
class Random_points_in_cube_d : public Random_generator_base<P>{
void generate_point();
int dimension;
public:
typedef Random_points_in_cube_d<P> This;
Random_points_in_cube_d( int dim, double a = 1,
Random& rnd = get_default_random())
: Random_generator_base<P>( a, rnd), dimension(dim) { generate_point(); }
This& operator++() {
generate_point();
return *this;
}
This operator++(int) {
This tmp = *this;
++(*this);
return tmp;
}
};
template < class P >
void
Random_points_in_cube_d<P>::
generate_point() {
typedef typename Kernel_traits<P>::Kernel::RT RT;
CGAL_assume(dimension>0);
std::vector<RT> coord(dimension);
for(int i=0; i<dimension; ++i)
coord[i]=RT(this->d_range * ( 2 * this->_rnd.get_double() - 1.0));
P p(dimension, coord.begin(), coord.end() );
this->d_item = p;
}
template <class OutputIterator, class Creator>
OutputIterator
points_on_cube_grid_d( int dimension, double a,
std::size_t n, OutputIterator o, Creator creator)
{
// typedef typename OutputIterator::container_type::value_type Point;
if (n == 0)
return o;
// take m smallest such that m^dimension > n
int m=int(std::floor(std::pow(static_cast<double>(n),1/(double)dimension)));
while(true) {
int nn=1;
for (int i=0; i<dimension; ++i) nn*=m;
if (std::size_t(nn)>=n) break;
++m;
}
double base = -a; // Left and bottom boundary.
double step = 2*a/(m-1);
std::vector<int> indices(dimension);
std::vector<double> coord(dimension);
//initialize indices
int j;
for(j=0; j< dimension; ++j) { indices[j]=0; }
std::size_t i=0;
while (true) {
//compute point
for(j=0; j< dimension; ++j) {
coord[j]=base+step*indices[j];
}
*o = creator(coord.begin(), coord.end() );
++i;
if (i==n) break;
++o;
// find index to increment
for ( j=0; j < dimension; ++j) if ( indices[j]<m-1 ) break;
// increment and reset smaller indices
CGAL_assertion(j<dimension);
indices[j]++;
while(j>0) { --j; indices[j]=0; }
}
return o;
}
} //namespace CGAL
#include <CGAL/enable_warnings.h>
#endif // CGAL_POINT_GENERATORS_D_H //
// EOF //
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