trunk/examples/interface/odd_even.cc

   1 // Odd/even face coloring code
   2 //
   3 // Author   : Chris H. Rycroft (LBL / UC Berkeley)
   4 // Email    : chr@alum.mit.edu
   5 // Date     : August 30th 2011
   6
   7 #include <vector>
   8 using namespace std;
   9
  10 #include "voro++.hh"
  11 using namespace voro;
  12
  13 // This function returns a random floating point number between 0 and 1
  14 double rnd() {return double(rand())/RAND_MAX;}
  15
  16 int main() {
  17         unsigned int i;
  18         double x,y,z,rsq,r;
  19         voronoicell v;
  20
  21         // Initialize the Voronoi cell to be a cube of side length 2, centered
  22         // on the origin
  23         v.init(-1,1,-1,1,-1,1);
  24
  25         // Cut the cell by 250 random planes which are all a distance 1 away
  26         // from the origin, to make an approximation to a sphere
  27         for(i=0;i<250;i++) {
  28                 x=2*rnd()-1;
  29                 y=2*rnd()-1;
  30                 z=2*rnd()-1;
  31                 rsq=x*x+y*y+z*z;
  32                 if(rsq>0.01&&rsq<1) {
  33                         r=1/sqrt(rsq);x*=r;y*=r;z*=r;
  34                         v.plane(x,y,z,1);
  35                 }
  36         }
  37
  38         // Calculate the orders of the faces and the normal vectors
  39         vector<int> f_vert;
  40         vector<double> nor;
  41         v.face_orders(f_vert);
  42         v.normals(nor);
  43
  44         // Output POV-Ray planes with textures based on whether a face is
  45         // composed of an odd or even number of edges
  46         const char* parity[2]={"even","odd"};
  47         FILE *fp=safe_fopen("odd_even_pl.pov","w");
  48         for(i=0;i<f_vert.size();i++)
  49                 fprintf(fp,"plane{<%g,%g,%g>,0.5 texture{t_%s}}\n"
  50                         ,nor[3*i],nor[3*i+1],nor[3*i+2]
  51                         ,parity[f_vert[i]&1]);
  52         fclose(fp);
  53
  54         // Save the Voronoi cell as a spheres and cylinders
  55         v.draw_pov(0,0,0,"odd_even_v.pov");
  56 }