\( \newcommand{\E}{\mathrm{E}} \) \( \newcommand{\A}{\mathrm{A}} \) \( \newcommand{\R}{\mathrm{R}} \) \( \newcommand{\N}{\mathrm{N}} \) \( \newcommand{\Q}{\mathrm{Q}} \) \( \newcommand{\Z}{\mathrm{Z}} \) \( \def\ccSum #1#2#3{ \sum_{#1}^{#2}{#3} } \def\ccProd #1#2#3{ \sum_{#1}^{#2}{#3} }\)

CGAL 4.8 - 2D Placement of Streamlines

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Stream_lines_2/stl_regular_field.cpp
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Stream_lines_2.h>
#include <CGAL/Runge_kutta_integrator_2.h>
#include <CGAL/Regular_grid_2.h>
#include <iostream>
#include <fstream>
typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
typedef CGAL::Regular_grid_2<K> Field;
typedef CGAL::Runge_kutta_integrator_2<Field> Runge_kutta_integrator;
typedef CGAL::Stream_lines_2<Field, Runge_kutta_integrator> Strl;
typedef Strl::Point_iterator_2 Point_iterator;
typedef Strl::Stream_line_iterator_2 Strl_iterator;
typedef Strl::Point_2 Point_2;
typedef Strl::Vector_2 Vector_2;
int main()
{
Runge_kutta_integrator runge_kutta_integrator;
/*data.vec.cin is an ASCII file containing the vector field values*/
std::ifstream infile("data/vnoise.vec.cin", std::ios::in);
double iXSize, iYSize;
unsigned int x_samples, y_samples;
iXSize = iYSize = 512;
infile >> x_samples;
infile >> y_samples;
Field regular_grid_2(x_samples, y_samples, iXSize, iYSize);
/*fill the grid with the appropreate values*/
for (unsigned int i=0;i<x_samples;i++)
for (unsigned int j=0;j<y_samples;j++)
{
double xval, yval;
infile >> xval;
infile >> yval;
regular_grid_2.set_field(i, j, Vector_2(xval, yval));
}
infile.close();
/* the placement of streamlines */
std::cout << "processing...\n";
double dSep = 3.5;
double dRat = 1.6;
Strl Stream_lines(regular_grid_2, runge_kutta_integrator,dSep,dRat);
std::cout << "placement generated\n";
/*writing streamlines to streamlines_on_regular_grid_1.stl */
std::ofstream fw("streamlines_on_regular_grid_1.stl",std::ios::out);
fw << Stream_lines.number_of_lines() << "\n";
for(Strl_iterator sit = Stream_lines.begin(); sit != Stream_lines.end(); sit++)
{
fw << "\n";
for(Point_iterator pit = sit->first; pit != sit->second; pit++){
Point_2 p = *pit;
fw << p.x() << " " << p.y() << "\n";
}
}
fw.close();
}