Program to fill a Circle using Scan-Line Circle Fill Algorithm using Polar Coordinates

 # include <iostream.h>
 # include <graphics.h>
 # include    <conio.h>
 # include     <math.h>


 void show_screen( );

 void Fill_circle(const int,const int,const int);

 void Circle(const int,const int,const int);
 void Line(const int,const int,const int,const int);


 int main( )
    {
       int driver=VGA;
       int mode=VGAHI; 

       int x=0;
       int y=0;
       int r=0;

       do
      {
         show_screen( );

         gotoxy(8,10);
         cout<<\"Coordinates of Center Point (x,y) :\";

         gotoxy(8,11);
         cout<<\"ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ\";

         gotoxy(12,13);
         cout<<\"Enter the value of x = \";
         cin>>x;

         gotoxy(12,14);
         cout<<\"Enter the value of y = \";
         cin>>y;

         gotoxy(8,18);
         cout<<\"Radius of Circle : r :\";

         gotoxy(8,19);
         cout<<\"ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ\";

         gotoxy(12,21);
         cout<<\"Enter the value of r = \";
         cin>>r;

         initgraph(&driver,&mode,\"..\\\\Bgi\");

         setcolor(15);
           Circle(x,y,r);

         setcolor(9);
           Fill_circle(x,y,(r-1));

         setcolor(15);
           outtextxy(110,460,\"Press <Enter> to continue or any other key to exit.\");

         int key=int(getch( ));

         if(key!=13)
        break;
      }
       while(1);

       return 0;
    }


 //---------------------------  Fill_circle( )  --------------------------//


 void Fill_circle(const int x,const int y,const int r)
    {
       int iterations=(int)((2*r*M_PI)+0.5);
       double angle;
       int x1;
       int y1;

       for(int count=0;count<=iterations;count++)
      {
         angle=(((2*M_PI*count)/iterations)+0.5);
         x1=int(x+(r*cos(angle))+0.5);
         y1=int(y+(r*sin(angle))+0.5);

         Line(x,y,x1,y1);
      }
    }


 //----------------------------  Circle( )  ------------------------------//


 void Circle(const int h,const int k,const int r)
    {
       int color=getcolor( );

       int x=0;
       int y=r;
       int p=(1-r);

       do
      {
         putpixel((h+x),(k+y),color);
         putpixel((h+y),(k+x),color);
         putpixel((h+y),(k-x),color);
         putpixel((h+x),(k-y),color);
         putpixel((h-x),(k-y),color);
         putpixel((h-y),(k-x),color);
         putpixel((h-y),(k+x),color);
         putpixel((h-x),(k+y),color);

         x++;

         if(p<0)
        p+=((2*x)+1);

         else
        {
           y--;
           p+=((2*(x-y))+1);
        }
      }
       while(x<=y);
    }


 //------------------------------  Line( )  ------------------------------//


 void Line(const int x_1,const int y_1,const int x_2,const int y_2)
    {
       int color=getcolor( );

       int x1=x_1;
       int y1=y_1;

       int x2=x_2;
       int y2=y_2;

       if(x_1>x_2)
      {
         x1=x_2;
         y1=y_2;

         x2=x_1;
         y2=y_1;
      }

       int dx=abs(x2-x1);
       int dy=abs(y2-y1);
       int inc_dec=((y2>=y1)?1:-1);

       if(dx>dy)
      {
         int two_dy=(2*dy);
         int two_dy_dx=(2*(dy-dx));
         int p=((2*dy)-dx);

         int x=x1;
         int y=y1;

         putpixel(x,y,color);

         while(x<x2)
        {
           x++;

           if(p<0)
              p+=two_dy;

           else
              {
             y+=inc_dec;
             p+=two_dy_dx;
              }

           putpixel(x,y,color);
        }
      }

       else
      {
         int two_dx=(2*dx);
         int two_dx_dy=(2*(dx-dy));
         int p=((2*dx)-dy);

         int x=x1;
         int y=y1;

         putpixel(x,y,color);

         while(y!=y2)
        {
           y+=inc_dec;

           if(p<0)
              p+=two_dx;

           else
              {
             x++;
             p+=two_dx_dy;
              }

           putpixel(x,y,color);
        }
      }
    }


 //--------------------------  show_screen( )  ---------------------------//


 void show_screen( )
    {
       restorecrtmode( );
       textmode(C4350);

       cprintf(\"\\n********************************************************************************\");
       cprintf(\"*********************-                                   -**********************\");
       cprintf(\"*--------------------- \");

       textbackground(1);
       cprintf(\" Scan-Line Circle Fill Algorithm \");
       textbackground(8);

       cprintf(\" ----------------------*\");
       cprintf(\"*********************-                                   -**********************\");
       cprintf(\"*-****************************************************************************-*\");

       for(int count=0;count<42;count++)
      cprintf(\"*-*                                                                          *-*\");

       gotoxy(1,46);
       cprintf(\"*-****************************************************************************-*\");
       cprintf(\"*------------------------------------------------------------------------------*\");
       cprintf(\"********************************************************************************\");

       gotoxy(1,2);
    }