/* 
fern.cc

code to draw the fractal "barnsley's fern."
example of iterated affine transformations

*/

#include <iostream>
#include <cstdlib>
#include <fstream>


using std::endl;
using std::cout;
using std::ofstream;

int main() 
{    
   int i;
   double x, y, xn, yn, r;
   
  // setup file i/o:

   ofstream out_file;
   const char out_file_name[] = "fern.dat";  // save data in fern.dat
   
   out_file.open(out_file_name); 

   x     = 0.5;				// starting point
   y     = 0.0;

   const int max = 50000;    // number of iterations
   srand((time(0)));         // seed random nmbr generator.
                             // srand & time built-in
   
   for(i=1; i<=max; ++i)     // iterations
     {
     r = rand()/(double)RAND_MAX;       // scale random nmbr
     
     if (r <= 0.02)			// stem
       { 
         xn = 0.5;
         yn = 0.27*y;
       }
      else if((r>0.02) && (r<=0.17))	// right leaf
	{ 
	xn = -0.139*x + 0.263*y + 0.57;
	yn =  0.246*x + 0.224*y - 0.036;
	}
      else if ((r>0.17) && (r<=0.3))	// left leaf
	{
	xn = 0.17*x  - 0.215*y + 0.408;
	yn = 0.222*x + 0.176*y + 0.0893;
	}  
      else 				// shoot
	{
	xn = 0.781*x + 0.034*y + 0.1075;
	yn = -0.032*x + 0.739*y + 0.27;
	}  
      
     x=xn;
     y=yn;
     out_file << x << " " << y << endl; // write date to output file  
     }
   out_file.close();
   cout << "data stored in fern.dat" << endl;

   return 0;
}