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

 /*************************************************************************///---------------------------  LineCoordinates  -------------------------///*************************************************************************/class LineCoordinates
    {
       public:
      float x_1;
      float y_1;
      float x_2;
      float y_2;

      LineCoordinates(constfloat x1,constfloat y1,
                          constfloat x2,constfloat y2)
         {
        x_1=x1;
        y_1=y1;
        x_2=x2;
        y_2=y2;
         }
    };

 /*************************************************************************///-------------------------  WindowCoordinates  -------------------------///*************************************************************************/class WindowCoordinates
    {
       public:
      float x_min;
      float y_min;
      float x_max;
      float y_max;

      WindowCoordinates(constfloat x1,constfloat y1,
                          constfloat x2,constfloat y2)
         {
        x_min=x1;
        y_min=y1;
        x_max=x2;
        y_max=y2;
         }
    };

 /*************************************************************************///-----------------------------  RegionCode  ----------------------------///*************************************************************************/class RegionCode
    {
       public:
      int bit_1;
      int bit_2;
      int bit_3;
      int bit_4;

      RegionCode( )
         {
        bit_1=0;
        bit_2=0;
        bit_3=0;
        bit_4=0;
         }

      constint equal_zero( )
         {
        if(bit_1==0 && bit_2==0 && bit_3==0 && bit_4==0)
           return 1;

        return 0;
         }

      void get_logical_AND(RegionCode rc1,RegionCode rc2)
         {
        if(rc1.bit_1==1 && rc2.bit_1==1)
           bit_1=1;

        if(rc1.bit_2==1 && rc2.bit_2==1)
           bit_2=1;

        if(rc1.bit_3==1 && rc2.bit_3==1)
           bit_3=1;

        if(rc1.bit_4==1 && rc2.bit_4==1)
           bit_4=1;
         }

      void get_region_code(const WindowCoordinates wc,
                           constint x,constint y)
         {
        if((wc.x_min-x)>0)
           bit_1=1;

        if((x-wc.x_max)>0)
           bit_2=1;

        if((wc.y_min-y)>0)
           bit_3=1;

        if((y-wc.y_max)>0)
           bit_4=1;
         }
    };


 void show_screen( );

 constint clip_line(const WindowCoordinates,LineCoordinates&);

 void calculate_intersecting_points(const WindowCoordinates,LineCoordinates&);

 void Rectangle(constint,constint,constint,constint);
 void Line(constint,constint,constint,constint);


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

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

       show_screen( );

       WindowCoordinates WC(180,140,470,340);

       setcolor(15);
     Rectangle(WC.x_min,WC.y_min,WC.x_max,WC.y_max);

       LineCoordinates LC_1(150,160,120,320);
       LineCoordinates LC_2(250,150,200,200);
       LineCoordinates LC_3(160,200,490,260);
       LineCoordinates LC_4(300,300,400,380);
       LineCoordinates LC_5(550,300,450,400);
       LineCoordinates LC_6(440,110,400,370);

       setcolor(7);
     Line(LC_1.x_1,LC_1.y_1,LC_1.x_2,LC_1.y_2);
     Line(LC_2.x_1,LC_2.y_1,LC_2.x_2,LC_2.y_2);
     Line(LC_3.x_1,LC_3.y_1,LC_3.x_2,LC_3.y_2);
     Line(LC_4.x_1,LC_4.y_1,LC_4.x_2,LC_4.y_2);
     Line(LC_5.x_1,LC_5.y_1,LC_5.x_2,LC_5.y_2);
     Line(LC_6.x_1,LC_6.y_1,LC_6.x_2,LC_6.y_2);

       char Key=NULL;

       do
      {
         Key=getch( );
      }
       while(Key!='C' && Key!='c');

       settextstyle(0,0,1);
     setcolor(0);
       outtextxy(163,450,"  Press 'C' to see the Clipped Lines.  ");

    setcolor(15);
       outtextxy(165,450,"------                          -------");

     setcolor(12);
       outtextxy(213,450,"  Press any Key to exit.  ");

       setcolor(10);

       if(clip_line(WC,LC_1))
      Line(LC_1.x_1,LC_1.y_1,LC_1.x_2,LC_1.y_2);

       if(clip_line(WC,LC_2))
      Line(LC_2.x_1,LC_2.y_1,LC_2.x_2,LC_2.y_2);

       if(clip_line(WC,LC_3))
      Line(LC_3.x_1,LC_3.y_1,LC_3.x_2,LC_3.y_2);

       if(clip_line(WC,LC_4))
      Line(LC_4.x_1,LC_4.y_1,LC_4.x_2,LC_4.y_2);

       if(clip_line(WC,LC_5))
      Line(LC_5.x_1,LC_5.y_1,LC_5.x_2,LC_5.y_2);

       if(clip_line(WC,LC_6))
      Line(LC_6.x_1,LC_6.y_1,LC_6.x_2,LC_6.y_2);

       getch( );
       return 0;
    }

 /*************************************************************************///---------------------------  clip_line( )  ----------------------------///*************************************************************************/constint clip_line(const WindowCoordinates wc,LineCoordinates &lc)
    {
       RegionCode rc1,rc2,rc;

       rc1.get_region_code(wc,lc.x_1,lc.y_1);
       rc2.get_region_code(wc,lc.x_2,lc.y_2);
       rc.get_logical_AND(rc1,rc2);

       if(rc1.equal_zero( ) && rc2.equal_zero( ))
      {
         lc.x_1=(int)(lc.x_1+0.5);
         lc.y_1=(int)(lc.y_1+0.5);
         lc.x_2=(int)(lc.x_2+0.5);
         lc.y_2=(int)(lc.y_2+0.5);

         return 1;
      }

       elseif(!rc.equal_zero( ))
      return 0;

       else
      {
         calculate_intersecting_points(wc,lc);
         clip_line(wc,lc);
      }

       return 1;
    }

 /*************************************************************************///-----------------  calculate_intersecting_points( )  ------------------///*************************************************************************/void calculate_intersecting_points(const WindowCoordinates wc,
                            LineCoordinates &lc)
    {
       RegionCode rc1,rc2,rc;

       rc1.get_region_code(wc,lc.x_1,lc.y_1);
       rc2.get_region_code(wc,lc.x_2,lc.y_2);

       if(!rc1.equal_zero( ))
      {
         float m;
         float x=lc.x_1;
         float y=lc.y_1;

         int dx=(lc.x_2-lc.x_1);

         if(dx!=0)
        m=((lc.y_2-lc.y_1)/(lc.x_2-lc.x_1));

         if(rc1.bit_1==1)
        {
           x=wc.x_min;
           y=(lc.y_1+(m*(x-lc.x_1)));
        }

         elseif(rc1.bit_2==1)
        {
           x=wc.x_max;
           y=(lc.y_1+(m*(x-lc.x_1)));
        }

         elseif(rc1.bit_3==1)
        {
           y=wc.y_min;

           if(dx!=0)
              x=(lc.x_1+((y-lc.y_1)/m));
        }

         elseif(rc1.bit_4==1)
        {
           y=wc.y_max;

           if(dx!=0)
              x=(lc.x_1+((y-lc.y_1)/m));
        }

         lc.x_1=x;
         lc.y_1=y;
      }

       if(!rc2.equal_zero( ))
      {
         float m;
         float x=lc.x_2;
         float y=lc.y_2;

         int dx=(lc.x_2-lc.x_1);

         if(dx!=0)
        m=((lc.y_2-lc.y_1)/(lc.x_2-lc.x_1));

         if(rc2.bit_1==1)
        {
           x=wc.x_min;
           y=(lc.y_2+(m*(x-lc.x_2)));
        }

         elseif(rc2.bit_2==1)
        {
           x=wc.x_max;
           y=(lc.y_2+(m*(x-lc.x_2)));
        }

         elseif(rc2.bit_3==1)
        {
           y=wc.y_min;

           if(dx!=0)
              x=(lc.x_2+((y-lc.y_2)/m));
        }

         elseif(rc2.bit_4==1)
        {
           y=wc.y_max;

           if(dx!=0)
              x=(lc.x_2+((wc.y_max-lc.y_2)/m));
        }

         lc.x_2=x;
         lc.y_2=y;
      }
    }

 /*************************************************************************///---------------------------  Rectangle( )  ----------------------------///*************************************************************************/void Rectangle(constint x_1,constint y_1,constint x_2,constint y_2)
    {
       Line(x_1,y_1,x_2,y_1);
       Line(x_2,y_1,x_2,y_2);
       Line(x_2,y_2,x_1,y_2);
       Line(x_1,y_2,x_1,y_1);
    }

 /*************************************************************************///-------------------------------  Line( )  -----------------------------///*************************************************************************/void Line(constint x_1,constint y_1,constint x_2,constint 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( )
    {
       setfillstyle(1,1);
     bar(145,26,480,38);

       settextstyle(0,0,1);
     setcolor(15);
       outtextxy(5,5,"******************************************************************************");
       outtextxy(5,17,"*-**************************************************************************-*");
       outtextxy(5,29,"*---------------                                             ----------------*");
       outtextxy(5,41,"*-**************************************************************************-*");
       outtextxy(5,53,"*-**************************************************************************-*");

     setcolor(11);
       outtextxy(152,29,"Cohen-Sutherland Line Clipping Algorithm");

     setcolor(15);

       for(int count=0;count<=30;count++)
          outtextxy(5,(65+(count*12)),"*-*                                                                        *-*");

       outtextxy(5,438,"*-**************************************************************************-*");
       outtextxy(5,450,"*-------------------                                       ------------------*");
       outtextxy(5,462,"******************************************************************************");

     setcolor(12);
       outtextxy(163,450,"  Press 'C' to see the Clipped Lines.  ");
    }