Mid-Point Algorithm for Circle Drawing in Computer Graphics

#include <graphics.h>

#include <stdio.h>

#include <conio.h>

void drawpoints(int,int,int,int);

void drawcircle(int,int,int);

void main()

{

  int gd = DETECT, gm;

  int xc,yc,r;

  initgraph(&gd, &gm, "C:\\TC\\BGI");

  printf("\n\nEnter the center co-ordinates:");

  scanf("%d%d",&xc,&yc);

  printf("Enter the radius");

  scanf("%d",&r);

  drawcircle(xc,yc,r);

  getch();

  closegraph();

}

void drawpoints(int x,int y, int xc,int yc)

{

  putpixel(xc+x,yc+y,1);

  putpixel(xc-x,yc+y,1);

  putpixel(xc+x,yc-y,1);

  putpixel(xc-x,yc-y,1);

  putpixel(xc+y,yc+x,1);

  putpixel(xc-y,yc+x,1);

  putpixel(xc+y,yc-x,1);

  putpixel(xc-y,yc-x,1);

}

void drawcircle(int xc,int yc,int r)

{

  int p,x,y;

  x=0;

  y=r;

  drawpoints(x,y,xc,yc);

  p=1-r;

  while(x<y)

  {

   if(p<0)

    {

      x=x+1;

      p=p+2*x+1;

    }

   else

    {

      x=x+1;

      y=y-1;

      p=p+2*(x-y)+1;

    }

   drawpoints(x,y,xc,yc);

  }

}

OUTPUT:

Ellipse Drawing Algorithm >>