Bresenhams-Circle-Drawing-Algorithm.cpp

/*
    Md. Abdul Mutalib
    B.Sc (Engg.) in CSE
    North East University Bangladesh

    Connect with me:
    Github: https://github.com/mamutalib
*/

#include <bits/stdc++.h>
#include<windows.h>
#include<GL/Glut.h>
#include<cstdlib>
#include<cstdio>
#include<cmath>
#include <iostream>

using namespace std;

#define ll long long
#define ull unsigned long long
#define ld long double
#define nl '\n'
#define fn for(int i = 0; i<n; i++)
#define ft for(int i = 0; i<t; i++)
#define wt while(t--)
#define wn while(n--)
#define fs first
#define f first
#define s second
#define pf printf
#define sc scanf

int x_center, y_center, r;

void plot(int x, int y) {
   glBegin(GL_POINTS);
   glVertex2i(x + x_center, y + y_center);
   glEnd();
}
void plotEightWay(int x, int y) {
   plot(x, y);
   plot(x, -y);
   plot(-x, y);
   plot(-x, -y);
   plot(y, x);
   plot(-y, x);
   plot(y, -x);
   plot(-y, -x);
}

void brasenhamCircle() {
   int x = 0;
   int y = r;
   float decision = 3 - (2 * r);
   plotEightWay(x, y);

   while (y > x) {
      if (decision <= 0) {
         decision = decision + (4 * x) + 6;
      } else {
         decision = decision + (4 * x) - (4 * y) + 10;
         y = y - 1;
      }
      x++;
      plotEightWay(x, y);
   }

}

void display(void) {
   brasenhamCircle();

   glFlush();
}
void init(void) {
   glClearColor(1.0, 1.0, 1.0, 0.0);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   gluOrtho2D(0.0, 640.0, 0.0, 480.0);
}

int main(int argc, char ** argv) {
   cout << "Enter the center co-ordinates and radius:\n";
   cin >> x_center >> y_center >> r;

   glutInit( & argc, argv);
   glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
   glutInitWindowSize(640, 480);
   glutInitWindowPosition(100, 150);
   glutCreateWindow("Bresenham Circle Drawing Algorithm");
   init();
   glutDisplayFunc(display);
   glutMainLoop();

   return 0;
}