A PROGRAM TO DRAW AN ELLIPSE USING MID-POINT ALGORITHM

  #include<graphics.h>

  #include<stdlib.h>

  #include<stdio.h>

  #include<conio.h>

  #include<time.h>

  #include<dos.h>

  int main(void)

  {

  int gd=DETECT,gm;

  int cenx,ceny;

  float Pk,a,b,x,y;

  clrscr();

  printf("\n\n Enter 'a' and 'b':");

  scanf("%f%f",&a,&b);

  initgraph(&gd,&gm,"c:\\tc\\bgi");

  cenx=getmaxx()/2;

  ceny=getmaxy()/2;

  Pk=b*b-b*a*a+0.25*a*a;

  x=0;

  y=b;

  putpixel(cenx+x,ceny+y,WHITE);

  putpixel(cenx+x,ceny-y,WHITE);

  putpixel(cenx-x,ceny+y,WHITE);

  putpixel(cenx-x,ceny-y,WHITE);

  while(2*x*b*b<=2*y*a*a)

  {

  if(Pk<0)

  {

  x=x+1;

  y=y;

  Pk=Pk+2*x*b*b+3*b*b;

  }

  else

  {

  x=x+1;

  y=y-1;

  Pk=Pk+2*x*b*b+3*b*b-2*y*a*a+2*a*a;

  }

  putpixel(cenx+x,ceny+y,WHITE);

  putpixel(cenx+x,ceny-y,WHITE);

  putpixel(cenx-x,ceny+y,WHITE);

  putpixel(cenx-x,ceny-y,WHITE);

  delay(40);

  }

  Pk=(x+0.5)*(x+0.5)*b*b+(y-1)*(y-1)*a*a-a*a*b*b;

  putpixel(cenx+x,ceny+y,WHITE);

  putpixel(cenx+x,ceny-y,WHITE);

  putpixel(cenx-x,ceny+y,WHITE);

  putpixel(cenx-x,ceny-y,WHITE);

  while(y>0)

  {

  if(Pk>0)

  {

  x=x;

  y=y-1;

  Pk=Pk-2*y*a*a+3*a*a;

  }

  else

  {

  x=x+1;

  y=y-1;

  Pk=Pk-2*y*a*a+3*a*a+2*x*b*b+2*b*b;

  }

  putpixel(cenx+x,ceny+y,WHITE);

  putpixel(cenx+x,ceny-y,WHITE);

  putpixel(cenx-x,ceny+y,WHITE);

  putpixel(cenx-x,ceny-y,WHITE);

  delay(40);

  }

  gotoxy(1,25);

  printf("\npress any key to exit");

  getch();

  closegraph();

  return 0;

  }


                                                               OUTPUT

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