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// Copyright (c) 2005 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/Stream_lines_2/include/CGAL/Regular_grid_2.h $
// $Id: include/CGAL/Regular_grid_2.h 08b27d3db14 $
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s) : Abdelkrim Mebarki <Abdelkrim.Mebarki@sophia.inria.fr>
#ifndef CGAL_REGULAR_GRID_2_H_
#define CGAL_REGULAR_GRID_2_H_
#include <CGAL/license/Stream_lines_2.h>
#include <CGAL/basic.h>
#include <CGAL/assertions.h>
#include <memory>
#include <vector>
namespace CGAL {
// The class Regular_grid_2 provides a rectangular visualization
// domain, with a vector field defined on a regular grid, and also a
// bilinear interpolation to extract the vector field values
template <class StreamLinesTraits_2>
class Regular_grid_2
{
public:
typedef Regular_grid_2<StreamLinesTraits_2> Vector_field_2;
typedef StreamLinesTraits_2 Geom_traits;
typedef typename StreamLinesTraits_2::FT FT;
typedef typename StreamLinesTraits_2::Point_2 Point_2;
typedef typename StreamLinesTraits_2::Vector_2 Vector_2;
protected:
std::shared_ptr< std::vector<FT> > vector_field;
inline int get_index(int i,int j) const;
int number_of_samples_x;
int number_of_samples_y;
FT domain_size_x;
FT domain_size_y;
Vector_2 get_vector_field(const Point_2 & p) const;
FT get_density_field(const Point_2 & p) const;
bool is_in_samples(int i,int j) const;
public:
Regular_grid_2(int m, int n,const FT & x, const FT & y);
// Regular_grid_2();
~Regular_grid_2()
{}
inline typename Geom_traits::Iso_rectangle_2 bbox() const;
std::pair<Vector_2,FT>
get_field(const Point_2 & p) const
{
CGAL_precondition(is_in_domain(p));
Vector_2 v = get_vector_field(p);
FT density = get_density_field(p);
return std::pair<Vector_2, FT>(v,density);
}
inline bool is_in_domain(const Point_2 & p) const;
inline FT get_integration_step(const Point_2 &) const;
inline FT get_integration_step() const;
inline void set_field(int i, int j, const Vector_2 & v);
inline Vector_2 get_field(int i, int j) const;
inline std::pair<int, int> get_dimension()
{
return std::pair<int, int>(number_of_samples_x, number_of_samples_y);
}
inline std::pair<FT, FT> get_size()
{
return std::pair<FT,
FT>(domain_size_x,
domain_size_y);
}
inline FT container_value(int i) const
{
if (i < 2*number_of_samples_x*number_of_samples_y)
return (*vector_field)[i];
else
return 0.0;
}
};
template <class StreamLinesTraits_2>
inline
typename StreamLinesTraits_2::Iso_rectangle_2
Regular_grid_2<StreamLinesTraits_2>::bbox() const
{
return typename Geom_traits::Iso_rectangle_2(0.0, 0.0,
domain_size_x,
domain_size_y);
}
template <class StreamLinesTraits_2>
inline int
Regular_grid_2<StreamLinesTraits_2>::get_index(int i, int j) const
{
return 2*(number_of_samples_x*j + i);
}
template <class StreamLinesTraits_2>
Regular_grid_2<StreamLinesTraits_2>::Regular_grid_2(int m,
int
n,const FT & x,
const FT & y)
{
number_of_samples_x = m;
number_of_samples_y = n;
domain_size_x = x;
domain_size_y = y;
vector_field = std::shared_ptr<std::vector<FT> >(new std::vector<FT>(number_of_samples_x*number_of_samples_y* 2));
}
template <class StreamLinesTraits_2>
inline typename Regular_grid_2<StreamLinesTraits_2>::Vector_2
Regular_grid_2<StreamLinesTraits_2>::get_field(int i, int j) const
{
CGAL_precondition(is_in_samples(i,j));
int index = get_index(i,j);
return Vector_2((*vector_field)[index], (*vector_field)[index+1]);
}
template <class StreamLinesTraits_2>
inline void
Regular_grid_2<StreamLinesTraits_2>::set_field(int i,
int j, const Vector_2
& v)
{
CGAL_precondition(is_in_samples(i,j));
int index = get_index(i,j);
(*vector_field)[index++] = v.x();
(*vector_field)[index] = v.y();
}
template <class StreamLinesTraits_2>
inline bool
Regular_grid_2<StreamLinesTraits_2>::is_in_domain(const Point_2 & p)
const
{
return ((p.x()>=0.0) && (p.x()<=domain_size_x) && (p.y()>=0.0) &&
(p.y()<=domain_size_y));
}
template <class StreamLinesTraits_2>
bool
Regular_grid_2<StreamLinesTraits_2>::is_in_samples(int i,
int j)
const
{
return ((i>=0) && (i<=number_of_samples_x-1) && (j>=0) &&
(j<=number_of_samples_y-1));
}
template <class StreamLinesTraits_2>
typename Regular_grid_2<StreamLinesTraits_2>::Vector_2
Regular_grid_2<StreamLinesTraits_2>::get_vector_field(const Point_2 &
p) const
{
FT fXv,fYv;
FT x = (p.x() / domain_size_x) * (number_of_samples_x-1);
FT y = (p.y() / domain_size_y) * (number_of_samples_y-1);
int i = (int) x;
int j = (int) y;
FT xfract = x - (FT) i;
FT yfract = y - (FT) j;
int iIndex_1 = get_index(i,j);
int iIndex_2 = get_index(i+1,j);
int iIndex_3 = get_index(i,j+1);
int iIndex_4 = get_index(i+1,j+1);
FT x00 = container_value(iIndex_1);
FT x01 = container_value(iIndex_2);
FT x10 = container_value(iIndex_3);
FT x11 = container_value(iIndex_4);
FT x0 = x00 + xfract * (x01 - x00);
FT x1 = x10 + xfract * (x11 - x10);
fXv = x0 + yfract * (x1 - x0);
iIndex_1++;
iIndex_2++;
iIndex_3++;
iIndex_4++;
FT y00 = container_value(iIndex_1);
FT y01 = container_value(iIndex_2);
FT y10 = container_value(iIndex_3);
FT y11 = container_value(iIndex_4);
FT y0 = y00 + xfract * (y01 - y00);
FT y1 = y10 + xfract * (y11 - y10);
fYv = y0 + yfract * (y1 - y0);
// normalization step
FT normal = sqrt((fXv)*(fXv) + (fYv)*(fYv));
fXv = fXv / normal;
fYv = fYv / normal;
Vector_2 v = Vector_2(fXv, fYv);
return v;
}
template <class StreamLinesTraits_2>
typename Regular_grid_2<StreamLinesTraits_2>::FT
Regular_grid_2<StreamLinesTraits_2>::get_density_field(const Point_2 & ) const
{
return 1.0;
}
template<class StreamLinesTraits_2>
inline
typename Regular_grid_2<StreamLinesTraits_2>::FT
Regular_grid_2<StreamLinesTraits_2>::get_integration_step(const Point_2 &)
const
{
return 1.0;
}
template<class StreamLinesTraits_2>
inline
typename Regular_grid_2<StreamLinesTraits_2>::FT
Regular_grid_2<StreamLinesTraits_2>::get_integration_step() const
{
return 1.0;
}
} //namespace CGAL
#endif
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