Circles Animation

#include<stdio.h>
#include<graphics.h>
#include<dos.h>
#include<conio.h>
#include<math.h>
#define pie 3.14

void init_graph();
void bresenham_circle(const int,const int,const int,int);

void main( )
{
 int ho = 95;
 int ko = 55;
 int ro = 25;
 int hi = 445;
 int ki = 145;
 int ri = 25;
 int hdo = 2;
 int hdi = -2;
 int kdo = 0;
 int kdi = 0;
 init_graph();

 do
 {
 rectangle(40,10,600,470);
 rectangle(150,100,490,380);
 bresenham_circle(hi,ki,ri,BLACK);
 bresenham_circle(ho,ko,ro,BLACK);
 ho += hdo;
 ko += kdo;
 hi += hdi;
 ki += kdi;
 if(ho == 95 && ko == 55)
 { hdo = 2; kdo = 0; }

 if(hi == 445 && ki == 145)
 { hdi = -2; kdi = 0; }

 if(ho == 545 && ko == 55)
 { hdo = 0; kdo = 2; }

 if(hi == 195 && ki == 145)
 { hdi = 0; kdi = 2; }

 if(ho == 95 && ko == 425)
 { hdo = 0; kdo = -2; }

 if(hi == 445 && ki == 335)
 { hdi = 0; kdi = -2; }

 if(ho == 545 && ko == 425)
 { hdo = -2; kdo = 0; }

 if(hi == 195 && ki == 335)
 { hdi = 2; kdi = 0; }


 bresenham_circle(hi,ki,ri,GREEN);
 bresenham_circle(ho,ko,ro,RED);

 delay(2);
 }while(!kbhit());
 getch();
}

void init_graph()
{
 int gdriver = DETECT, gmode, errorcode;
 initgraph(&gdriver, &gmode, "");
 errorcode = graphresult();
 if (errorcode != grOk)  /* an error occurred */
 {
   printf("Graphics error: %s\n", grapherrormsg(errorcode));
   printf("Press any key to halt:");
   getch();
 }
}



void bresenham_circle(const int h,const int k,const int r,int col)
{
 int x=0;
 int y=r;
 int p=(3-(2*r));
 do
 {
  putpixel(h+x,k+y,col);
  putpixel(h+y,k+x,col);
  putpixel(h+y,k-x,col);
  putpixel(h+x,k-y,col);
  putpixel(h-x,k-y,col);
  putpixel(h-y,k-x,col);
  putpixel(h-y,k+x,col);
  putpixel(h-x,k+y,col);
  x++;
  if(p<0)
   p+=((4*x)+6);
  else
  {
   y--;
   p+=((4*(x-y))+10);
  }
 }while(x<=y);

}