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