#include <iostream>
#include <vector>
#include <math.h>


int res_x = 1024;
int res_y = 968;
std::vector<bool> pixel;

void plot(int _x, int _y)
{
  //the center of the circle is always center of the image
  _x += res_x/2;
  _y += res_y/2;
  if (_x < 0 || _x >= res_x || _y < 0 || _y >= res_y)
    return;
  else
    pixel[res_x * _y + _x] = true;
}


int main()
{
  int R = 100;
  int x = 0;
  int y = 0;
  int F = 0;
  
  //clear image
  pixel.resize(res_x*res_y,0);


  ///Algorithm 1 (Naiver Algorithmus für N=7R)
  
    for (int j = 0; j < 7*R; ++j)
    {
      x = int(float(R) * cos(2.0*M_PI*float(j)/float(7*R)));
      y = int(float(R) * sin(2.0*M_PI*float(j)/float(7*R)));
      plot (x,y);
    }
  

  
  ///Algorithm 2 (Verbesserter Naiver Algorithmus)
    int y1 = 0;
    
    //9:00 - 12:00
    int y0 = 0;
    for (x = -R; x <= 0; ++x)
    {
      y1 = int(sqrt(R*R - x*x));
      for (y = y0; y <= y1; ++y)
      {
        plot(x,y); plot(x,-y);
      }
      y0 = y1;
    }
    //3:00 - 12:00
    y0 = 0;
    for (x = R; x > 0; --x)
    {
      y1 = int(sqrt(R*R - x*x));
      for (y = y0; y <= y1; ++y)
      {
        plot(x,y); plot(x,-y);
      }
      y0 = y1;
    }
  

 
  ///Algorithm 3 (Verbesserter Bresenham-Algorithmus)

    x = 0; y = R;
    F = 1 - R;
    while (x < y)
    {
      ++x;
      if (F < 0)
      {
        F += 2*x - 1;
      }
      else
      {
        F += 2*(x - y);
        --y;
      }
      plot(x,y), plot(y,x);
      plot(-x,y), plot(y,-x);
      plot(x,-y), plot(-y,x);
      plot(-x,-y), plot(-y,-x);
    }

  return 0;
}