branches/2d/examples/walls/polygon.cc

   1 #include <cmath>
   2 using namespace std;
   3
   4 #include "voro++_2d.hh"
   5 using namespace voro;
   6
   7 const double pi=3.1415926535897932384626433832795;
   8 const double radius=0.5;
   9 const int n=5;
  10
  11 // This function returns a random floating point number between 0 and 1
  12 double rnd() {return double(rand())/RAND_MAX;}
  13
  14 int main() {
  15         int i=0;double x,y,arg;
  16
  17         // Initialize the container class to be the unit square, with
  18         // non-periodic boundary conditions. Divide it into a 10 by 10 grid, with
  19         // an initial memory allocation of 8 particles per grid square.
  20         container_2d con(-1,1,-1,1,10,10,false,false,8);
  21
  22         // Add circular wall object
  23         wall_plane_2d *wc[n];
  24         for(i=0,arg=0;i<n;i++,arg+=2*pi/n) {
  25                 wc[i]=new wall_plane_2d(sin(arg),-cos(arg),radius);
  26                 con.add_wall(wc[i]);
  27         }
  28
  29         // Add 1000 random points to the container
  30         while(i<1000) {
  31                 x=2*rnd()-1;
  32                 y=2*rnd()-1;
  33                 if(con.point_inside(x,y)) {
  34                         con.put(i,x,y);
  35                         i++;
  36                 }
  37         }
  38
  39         // Output the particle positions to a file
  40         con.draw_particles("polygon.par");
  41
  42         // Output the Voronoi cells to a file, in the gnuplot format
  43         con.draw_cells_gnuplot("polygon.gnu");
  44
  45         // Sum the Voronoi cell areas and compare to the circle area
  46         double carea=n*radius*radius*tan(pi/n),varea=con.sum_cell_areas();
  47         printf("Total polygon area      : %g\n"
  48                "Total Voronoi cell area : %g\n"
  49                "Difference              : %g\n",carea,varea,varea-carea);
  50
  51         // Since they were dynamically allocated, delete the wall_plane_2d
  52         // objects
  53         for(i=0;i<n;i++) delete wc[i];
  54 }