midpoint

#include<stdio.h>

#include<conio.h>

#include<GL/gl.h>

#include<GL/glu.h>

#include<GL/glut.h>

#include<stdlib.h>

int r,x,y;

void disp()

{

       glClear(GL_COLOR_BUFFER_BIT);

     glColor3f(1.0,0.0,0.0);

     glPointSize(2.0); // to set size to pixels

     glBegin(GL_POINTS);

int p;

x=0;y=r;

p=1-r;

while(x<=y)

{

        if(p<0)

        {

               x=x+1;

               y=y;

               p=p+2*(x)+1;

               glVertex2f(x,y);

               glVertex2f(x,-y);

               glVertex2f(-x,-y);

               glVertex2f(-x,y);

               glVertex2f(y,x);

               glVertex2f(y,-x);

               glVertex2f(-y,-x);

               glVertex2f(-y,x);

               printf("x=%d,y=%d \n",x,y);

        }

        else

        {

            x=x+1;

            y=y-1;

            p=p+2*(x-y);

            glVertex2f(x,y);

            glVertex2f(x,-y);

            glVertex2f(-x,-y);

            glVertex2f(-x,y);

            glVertex2f(y,x);

            glVertex2f(y,-x);

            glVertex2f(-y,-x);

            glVertex2f(-y,x);

            printf("x=%d,y=%d \n",x,y);

        } 

}

glEnd();

glFlush();

}

void abc()

{

     glClearColor(0.0,0.0,0.0,1.0);

     glMatrixMode(GL_PROJECTION);

     glLoadIdentity();

     glOrtho(-100.0,100.0,-100.0,100.0,-1.0,1.0);

     }              

int  main()

{

       printf("Enter radius");

      scanf("%d",&r);

      glutInitDisplayMode(GLUT_RGB|GLUT_SINGLE);

      glutInitWindowSize(500,500);

      glutCreateWindow("Bresenham's");

      glutInitWindowPosition(50,50);

          abc();

      glutDisplayFunc(disp);

      glutMainLoop();

      return 0;

      }