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

 void show_screen( );

 void Bezier_curve(constint [8]);

 double nCr(int,int);
 double factorial(int);

 void Dashed_line(constint,constint,constint,constint,constint=0);


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

       int control_points[8]={0};

       do
      {
         show_screen( );

         for(int count=0;count<=3;count++)
        {
           gotoxy(8,10);
           cout<<"Coordinates of Point-"<<count<<" (x"<<count<<",y"<<count<<") :";

           gotoxy(8,11);
           cout<<"ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ";

           gotoxy(12,13);
           cout<<"Enter the value of x"<<count<<" = ";
           cin>>control_points[(count*2)];

           gotoxy(12,15);
           cout<<"Enter the value of y"<<count<<" = ";
           cin>>control_points[((count*2)+1)];

           gotoxy(8,10);
           cout<<"                                            ";

           gotoxy(12,13);
           cout<<"                                            ";

           gotoxy(12,15);
           cout<<"                                            ";
         }

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

         setcolor(15);
           Bezier_curve(control_points);

         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;
    }


 /*************************************************************************///--------------------------  Bezier_curve( )  --------------------------///*************************************************************************/void Bezier_curve(constint cp[8])
    {
       int color=getcolor( );

       setcolor(7);

       for(int count=0;count<3;count++)
      Dashed_line(cp[(count*2)],cp[((count*2)+1)],
                    cp[((count+1)*2)],cp[(((count+1)*2)+1)]);

       float x;
       float y;

       for(float u=0.0005;u<=1;u+=0.0005)
      {
         x=0;
         y=0;

         for(int k=0;k<=3;k++)
        {
           x+=(cp[(k*2)]*nCr(3,k)*pow(u,k)*powl((1-u),(3-k)));
           y+=(cp[((k*2)+1)]*nCr(3,k)*pow(u,k)*powl((1-u),(3-k)));
        }

         putpixel((int)(x+0.5),(int)(y+0.5),color);
      }
    }

 /*************************************************************************///------------------------------  nCr( )  -------------------------------///*************************************************************************/double nCr(int n,int r)
    {
       double nf;
       double rf;
       double nrf;
       double ncr;

       nf=factorial(n);
       rf=factorial(r);
       nrf=factorial((n-r));

       ncr=(nf/(rf*nrf));

       return ncr;
    }

 /*************************************************************************///---------------------------  factorial( )  ----------------------------///*************************************************************************/double factorial(int number)
    {
       double factorial=1;

       if(number==0 || number==1);

       else
      {
         for(int count=1;count<=number;count++)
        factorial=factorial*count;
      }

       return factorial;
    }

 /*************************************************************************///---------------------------  Dashed_line( )  --------------------------///*************************************************************************/void Dashed_line(constint x_1,constint y_1,constint x_2,
                      constint y_2,constint line_type)
    {
       int count=0;
       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;
              }

           if((count%2)!=0 && line_type==0)
              putpixel(x,y,color);

           elseif((count%5)!=4 && line_type==1)
              putpixel(x,y,color);

           elseif((count%10)!=8 && (count%10)!=9 && line_type==2)
              putpixel(x,y,color);

           elseif((count%20)!=18 && (count%20)!=19 && line_type==3)
              putpixel(x,y,color);

           elseif((count%12)!=7 && (count%12)!=8 &&
                (count%12)!=10 && (count%12)!=11 && line_type==4)
              putpixel(x,y,color);

           count++;
        }
      }

       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;
              }

           if((count%2)!=0 && line_type==0)
              putpixel(x,y,color);

           elseif((count%5)!=4 && line_type==1)
              putpixel(x,y,color);

           elseif((count%10)!=8 && (count%10)!=9 && line_type==2)
              putpixel(x,y,color);

           elseif((count%20)!=18 && (count%20)!=19 && line_type==3)
              putpixel(x,y,color);

           elseif((count%12)!=7 && (count%12)!=8 &&
                (count%12)!=10 && (count%12)!=11 && line_type==4)
              putpixel(x,y,color);

           count++;
        }
      }
    }

 /*************************************************************************///--------------------------  show_screen( )  ---------------------------///*************************************************************************/void show_screen( )
    {
       restorecrtmode( );
       clrscr( );
       textmode(C4350);

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

       textbackground(1);
       cprintf(" Cubic Bezier Curve ");
       textbackground(8);

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

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

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

       gotoxy(1,2);
    }