4-bit region code or Cohen-Sutherland Line clipping program in C graphics.

                                 SOURCE CODE

#include<iostream.h>
#include<conio.h>
#include<graphics.h>
void main()
{
int gd=DETECT,gm;
initgraph(&gd,&gm,"");
float w[5][2];
int i;
cout<<"Enter the co-ordinates of window:-\n"    ;
int xmin,ymin,xmax,ymax;
cout<<"xmin"<<" "<<"ymin"<<":";
cin>>xmin>>ymin;
cout<<"xmax"<<" "<<"ymax"<<":";
cin>>xmax>>ymax;
line(xmin,ymin,xmax,ymin);
line(xmax,ymin,xmax,ymax);
line(xmax,ymax,xmin,ymax);
line(xmin,ymax,xmin,ymin);
float x1,x2,y1,y2,m;
float dy,dx;
float st[4][2];
int print[2][2];
int print1[2][2];
int print2[2][2];
int flag=0;
float final[4][2];
float final1[2][2];
char ch='y';
while(ch=='Y'||ch=='y')
{
cout<<"\nEnter the line co-ordinates:-\n" ;
int ln[2][2];
for(i=0;i<2;i++)
{
  cout<<"x"<<i<<" y"<<i<<":-";
  cin>>ln[i][0]>>ln[i][1];                       //FOR LINE
}
for(i=0;i<1;i++)
{
  line(ln[i][0],ln[i][1],ln[i+1][0],ln[i+1][1]);
}
int bit1[4];
for(i=0;i<1;i++)
{
   int res1;
   res1=ln[i][0]-xmin;
   if(res1<0)
     bit1[0]=1;
   else
     bit1[0]=0;
   //Region code for 1st point
int res2;
   res2=xmax-ln[i][0];
   if(res2<0)
     bit1[1]=1;
   else
     bit1[1]=0;
int res3;
   res3=ln[i][1]-ymin;
   if(res3<0)
     bit1[2]=1;
   else
     bit1[2]=0;
int res4;
   res4=ymax-ln[i][1];
   if(res4<0)
     bit1[3]=1;
   else
     bit1[3]=0;
}

int bit2[4];
for(i=1;i<2;i++)
{
   int res1;
   res1=ln[i][0]-xmin;
   if(res1<0)
     bit2[0]=1;
   else
     bit2[0]=0;
   //Region code for 2nd point
int res2;
   res2=xmax-ln[i][0];
   if(res2<0)
     bit2[1]=1;
   else
     bit2[1]=0;
int res3;
   res3=ln[i][1]-ymin;
   if(res3<0)
     bit2[2]=1;
   else
     bit2[2]=0;
int res4;
   res4=ymax-ln[i][1];
   if(res4<0)
     bit2[3]=1;
   else
     bit2[3]=0;
}
int sum1=0,sum2=0;
cout<<"\nRegion code for 1st point:-";
for(i=3;i>=0;i--)
 {                                              //Printing region code
   sum1+=bit1[i];
   cout<<bit1[i];
 }
cout<<"\nRegion code for 2nd point:-";
for(i=3;i>=0;i--)
 { sum2+=bit2[i];                               //Printing region code
   cout<<bit2[i];
 }

int rsum=0 ;
int res[4];
for(i=0;i<4;i++)
{
  res[i]=bit1[i]&bit2[i];
}
cout<<"\n\nResult of AND operation is:-";        //AND oprn on Region code
for(i=3;i>=0;i--)
{
  rsum+=res[i];
  cout<<res[i];
}
if((sum1==0)&&(sum2==0))
{
  cout<<"\nLine is completely inside the window!!";
     for(i=0;i<1;i++)
       {
       setcolor(GREEN);
line(ln[i][0],ln[i][1],ln[i+1][0],ln[i+1][1]);
       }
}
else if(rsum>0)
{
  cout<<"\nLine is completely outside the window!!";
}
else
{
    if(sum1>=1&&sum2>=1)
    {
  cout<<"\nLine is partially inside the window!!";
   dy=ln[1][1]-ln[0][1];
   dx=ln[1][0]-ln[0][0];
   m=dy/dx;

   y1=ln[0][1]+(m*(xmin-ln[0][0])) ;   //left intercept
   y2=ln[0][1]+(m*(xmax-ln[0][0])) ;   //right intercept
   x1=ln[0][0]+((ymax-ln[0][1])/m);       //top intercept
   x2=ln[0][0]+((ymin-ln[0][1])/m);       //bottom intercept
  st[0][0]=xmin;                       //storing left-intercept co-ordinate
  st[0][1]=y1;
  st[1][0]=xmax;                       //storing right-intercept co-ordinate
  st[1][1]=y2;
  st[2][0]=x1;                       //storing top-intercept co-ordinate
  st[2][1]=ymax;
  st[3][0]=x2;                       //storing bottom-intercept co-ordinate
  st[3][1]=ymin;
cout<<"\nLeft,Right,Top & Bottom Co-ordinates resp.:-";
for(i=0;i<4;i++)
{
  cout<<"\n";
  cout<<"x"<<i<<" y"<<i<<":-"<<st[i][0]<<" "<<st[i][1];
}
cout<<"\nVisible portion of the line is:-" ;
  for(i=0;i<4;i++)
  {
    if(((st[i][0]>=xmin)&&(st[i][0]<=xmax))&&((st[i][1]>=ymin)&&(st[i][1]<=ymax)))
       {
       final[i][0]=st[i][0];
       final[i][1]=st[i][1];
   print1[0][0]=st[i][0];
   print1[0][1]=st[i][1];
   ++flag;
   if(flag==1)
   {
   print2[0][0]=st[i][0];
   print2[0][1]=st[i][1];
   }
       cout<<"("<<final[i][0]<<","<<final[i][1]<<")";
       }
   }
setcolor(GREEN);
line(print1[0][0],print1[0][1],print2[0][0],print2[0][1]);
//if((final[0][0]==st[0][0])&&(final[0][1]==st[0][1]))
 }  //if close

 else if(sum1==1&&sum2==0)
    {
       cout<<"\nLine is partially inside the window!!";
       dy=ln[1][1]-ln[0][1];
       dx=ln[1][0]-ln[0][0];
       m=dy/dx;
      //compairing region codes
       if(bit1[3]==0 && bit1[2]==0 && bit1[1]==0 && bit1[0]==1)
    {
    y1=ln[0][1]+(m*(xmin-ln[0][0])) ;   //left intercept
    st[0][0]=xmin;                       //storing left-intercept co-ordinate
    st[0][1]=y1;
    cout<<"\nVisible portion of the line is:";
    cout<<"("<<st[0][0]<<","<<st[0][1]<<") to ("<<ln[1][0]<<","<<ln[1][1]<<")";
    setcolor(GREEN);
    line(st[0][0],st[0][1],ln[1][0],ln[1][1]);
    goto Label1;
    }
      else if(bit1[3]==0 && bit1[2]==0 && bit1[1]==1 && bit1[0]==0)
    {
    y2=ln[0][1]+(m*(xmax-ln[0][0])) ;   //right intercept
    st[0][0]=xmax;                       //storing right-intercept co-ordinate
    st[0][1]=y2;
    cout<<"\nVisible portion of the line is:";
    cout<<"("<<st[0][0]<<","<<st[0][1]<<") to ("<<ln[1][0]<<","<<ln[1][1]<<")";
    setcolor(GREEN);
    line(st[0][0],st[0][1],ln[1][0],ln[1][1]);
    goto Label1;
    }

      else if(bit1[3]==1 && bit1[2]==0 && bit1[1]==0 && bit1[0]==0)
    {
    x1=ln[0][0]+((ymax-ln[0][1])/m);   //top intercept
     st[0][0]=x1;                       //storing top-intercept co-ordinate
     st[0][1]=ymax;
    cout<<"\nVisible portion of the line is:";
    cout<<"("<<st[0][0]<<","<<st[0][1]<<") to ("<<ln[1][0]<<","<<ln[1][1]<<")";
    setcolor(GREEN);
    line(st[0][0],st[0][1],ln[1][0],ln[1][1]);
    goto Label1;
    }
       else if(bit1[3]==0 && bit1[2]==1 && bit1[1]==0 && bit1[0]==0)
    {
    x2=ln[0][0]+((ymin-ln[0][1])/m);   //bottom intercept
     st[0][0]=x2;                       //storing bottom-intercept co-ordinate
     st[0][1]=ymin;
    cout<<"\nVisible portion of the line is:";
    cout<<"("<<st[0][0]<<","<<st[0][1]<<") to ("<<ln[1][0]<<","<<ln[1][1]<<")";
    setcolor(GREEN);
    line(st[0][0],st[0][1],ln[1][0],ln[1][1]);
    goto Label1;
    }
      }

    else if(sum1==0&&sum2==1)
    {
       cout<<"\nLine is partially inside the window!!";
       dy=ln[1][1]-ln[0][1];
       dx=ln[1][0]-ln[0][0];
       m=dy/dx;
      //compairing region codes
       if(bit2[3]==0 && bit2[2]==0 && bit2[1]==0 && bit2[0]==1)
    {
    y1=ln[0][1]+(m*(xmin-ln[0][0])) ;   //left intercept
    st[0][0]=xmin;                       //storing left-intercept co-ordinate
    st[0][1]=y1;
    cout<<"\nVisible portion of the line is:";
    cout<<"("<<st[0][0]<<","<<st[0][1]<<") to ("<<ln[0][0]<<","<<ln[0][1]<<")";
    setcolor(GREEN);
    line(st[0][0],st[0][1],ln[0][0],ln[0][1]);
    goto Label1;
    }
      else if(bit2[3]==0 && bit2[2]==0 && bit2[1]==1 && bit2[0]==0)
    {
    y2=ln[0][1]+(m*(xmax-ln[0][0])) ;   //right intercept
    st[0][0]=xmax;                       //storing right-intercept co-ordinate
    st[0][1]=y2;
    cout<<"\nVisible portion of the line is:";
    cout<<"("<<st[0][0]<<","<<st[0][1]<<") to ("<<ln[0][0]<<","<<ln[0][1]<<")";
    setcolor(GREEN);
    line(st[0][0],st[0][1],ln[0][0],ln[0][1]);
    goto Label1;
    }

      else if(bit2[3]==1 && bit2[2]==0 && bit2[1]==0 && bit2[0]==0)
    {
    x1=ln[0][0]+((ymax-ln[0][1])/m);   //top intercept
     st[0][0]=x1;                       //storing top-intercept co-ordinate
     st[0][1]=ymax;
    cout<<"\nVisible portion of the line is:";
    cout<<"("<<st[0][0]<<","<<st[0][1]<<") to ("<<ln[0][0]<<","<<ln[0][1]<<")";
    setcolor(GREEN);
    line(st[0][0],st[0][1],ln[0][0],ln[0][1]);
    goto Label1;
    }
       else if(bit2[3]==0 && bit2[2]==1 && bit2[1]==0 && bit2[0]==0)
    {
    x2=ln[0][0]+((ymin-ln[0][1])/m);   //bottom intercept
     st[0][0]=x2;                       //storing bottom-intercept co-ordinate
     st[0][1]=ymin;
    cout<<"\nVisible portion of the line is:";
    cout<<"("<<st[0][0]<<","<<st[0][1]<<") to ("<<ln[0][0]<<","<<ln[0][1]<<")";
    setcolor(GREEN);
    line(st[0][0],st[0][1],ln[0][0],ln[0][1]);
    goto Label1;
    }
      }

     else if(sum1==2&&sum2==0)
  {
  cout<<"\n\nLine is partially inside the window!!";
dy=ln[1][1]-ln[0][1];
dx=ln[1][0]-ln[0][0];
m=dy/dx;
     if(bit1[3]==0 && bit1[2]==1 && bit1[1]==0 && bit1[0]==1)
    {
    y1=ln[0][1]+(m*(xmin-ln[0][0])) ;   //left intercept
    x2=ln[0][0]+((ymin-ln[0][1])/m);      //bottom intercept
    st[0][0]=xmin;                       //storing left-intercept co-ordinate
    st[0][1]=y1;
    st[1][0]=x2;                         //storing bottom-intercept co-ordinate
    st[1][1]=ymin;
    cout<<"\nLeft intercept:";
    cout<<st[0][0]<<","<<st[0][1];
    cout<<"\nBottom intercept:";
    cout<<st[1][0]<<","<<st[1][1];
     cout<<"\n\nVisible portion of the line is:";
    for(i=0;i<2;i++)
      {
      if(((st[i][0]>=xmin)&&(st[i][0]<=xmax))&&((st[i][1]>=ymin)&&(st[i][1]<=ymax)))
{
       final1[i][0]=st[i][0];
       final1[i][1]=st[i][1];
print[0][0]=st[i][0];
print[0][1]=st[i][1];
       cout<<"("<<final1[i][0]<<","<<final1[i][1]<<")";
}
      }
    cout<<" to ("<<ln[1][0]<<","<<ln[1][1]<<")";
       setcolor(GREEN);
       line(print[0][0],print[0][1],ln[1][0],ln[1][1]);
    goto Label1;
    }

     if(bit1[3]==0 && bit1[2]==1 && bit1[1]==1 && bit1[0]==0)
    {
    y2=ln[0][1]+(m*(xmax-ln[0][0])) ;   //right intercept
    x2=ln[0][0]+((ymin-ln[0][1])/m);      //bottom intercept
    st[0][0]=xmax;                       //storing right-intercept co-ordinate
    st[0][1]=y2;
    st[1][0]=x2;                         //storing bottom-intercept co-ordinate
    st[1][1]=ymin;
    cout<<"\nRight intercept:";
    cout<<st[0][0]<<","<<st[0][1];
    cout<<"\nBottom intercept:";
    cout<<st[1][0]<<","<<st[1][1];
     cout<<"\n\nVisible portion of the line is:";
    for(i=0;i<2;i++)
      {
      if(((st[i][0]>=xmin)&&(st[i][0]<=xmax))&&((st[i][1]>=ymin)&&(st[i][1]<=ymax)))
{
       final1[i][0]=st[i][0];
       final1[i][1]=st[i][1];
  print[0][0]=st[i][0];
print[0][1]=st[i][1];
       cout<<"("<<final1[i][0]<<","<<final1[i][1]<<")";
}
      }
    cout<<" to ("<<ln[1][0]<<","<<ln[1][1]<<")";
    setcolor(GREEN);
       line(print[0][0],print[0][1],ln[1][0],ln[1][1]);
    goto Label1;
    }

    if(bit1[3]==1 && bit1[2]==0 && bit1[1]==1 && bit1[0]==0)
    {
    y2=ln[0][1]+(m*(xmax-ln[0][0])) ;   //right intercept
    x1=ln[0][0]+((ymax-ln[0][1])/m);      //top intercept
    st[0][0]=xmax;                       //storing right-intercept co-ordinate
    st[0][1]=y2;
    st[1][0]=x1;                         //storing top-intercept co-ordinate
    st[1][1]=ymax;
    cout<<"\nRight intercept:";
    cout<<st[0][0]<<","<<st[0][1];
    cout<<"\nTop intercept:";
    cout<<st[1][0]<<","<<st[1][1];
     cout<<"\n\nVisible portion of the line is:";
    for(i=0;i<2;i++)
      {
      if(((st[i][0]>=xmin)&&(st[i][0]<=xmax))&&((st[i][1]>=ymin)&&(st[i][1]<=ymax)))
{
       final1[i][0]=st[i][0];
       final1[i][1]=st[i][1];
  print[0][0]=st[i][0];
print[0][1]=st[i][1];
       cout<<"("<<final1[i][0]<<","<<final1[i][1]<<")";
}
      }
    cout<<" to ("<<ln[1][0]<<","<<ln[1][1]<<")";
    setcolor(GREEN);
       line(print[0][0],print[0][1],ln[1][0],ln[1][1]);
    goto Label1;
    }

      if(bit1[3]==1 && bit1[2]==0 && bit1[1]==0 && bit1[0]==1)
    {
    y1=ln[0][1]+(m*(xmin-ln[0][0])) ;   //left intercept
    x1=ln[0][0]+((ymax-ln[0][1])/m);      //top intercept
    st[0][0]=xmin;                       //storing left-intercept co-ordinate
    st[0][1]=y1;
    st[1][0]=x1;                         //storing top-intercept co-ordinate
    st[1][1]=ymax;
    cout<<"\nLeft intercept:";
    cout<<st[0][0]<<","<<st[0][1];
    cout<<"\nTop intercept:";
    cout<<st[1][0]<<","<<st[1][1];
     cout<<"\n\nVisible portion of the line is:";
    for(i=0;i<2;i++)
      {
      if(((st[i][0]>=xmin)&&(st[i][0]<=xmax))&&((st[i][1]>=ymin)&&(st[i][1]<=ymax)))
{
       final1[i][0]=st[i][0];
       final1[i][1]=st[i][1];
   print[0][0]=st[i][0];
print[0][1]=st[i][1];
       cout<<"("<<final1[i][0]<<","<<final1[i][1]<<")";
}
      }
    cout<<" to ("<<ln[1][0]<<","<<ln[1][1]<<")";
    setcolor(GREEN);
       line(print[0][0],print[0][1],ln[1][0],ln[1][1]);
    goto Label1;
    }
    }
    else if(sum1==0&&sum2==2)
  {
  cout<<"\n\nLine is partially inside the window!!";
dy=ln[1][1]-ln[0][1];
dx=ln[1][0]-ln[0][0];
m=dy/dx;
     if(bit2[3]==0 && bit2[2]==1 && bit2[1]==0 && bit2[0]==1)
    {
    y1=ln[0][1]+(m*(xmin-ln[0][0])) ;   //left intercept
    x2=ln[0][0]+((ymin-ln[0][1])/m);      //bottom intercept
    st[0][0]=xmin;                       //storing left-intercept co-ordinate
    st[0][1]=y1;
    st[1][0]=x2;                         //storing bottom-intercept co-ordinate
    st[1][1]=ymin;
    cout<<"\nLeft intercept:";
    cout<<st[0][0]<<","<<st[0][1];
    cout<<"\nBottom intercept:";
    cout<<st[1][0]<<","<<st[1][1];
     cout<<"\n\nVisible portion of the line is:";
    for(i=0;i<2;i++)
      {
      if(((st[i][0]>=xmin)&&(st[i][0]<=xmax))&&((st[i][1]>=ymin)&&(st[i][1]<=ymax)))
{
       final1[i][0]=st[i][0];
       final1[i][1]=st[i][1];
   print[0][0]=st[i][0];
print[0][1]=st[i][1];
       cout<<"("<<final1[i][0]<<","<<final1[i][1]<<")";
}
      }
    cout<<" to ("<<ln[0][0]<<","<<ln[0][1]<<")";
    setcolor(GREEN);
       line(print[0][0],print[0][1],ln[0][0],ln[0][1]);
    goto Label1;
    }

     if(bit2[3]==0 && bit2[2]==1 && bit2[1]==1 && bit2[0]==0)
    {
    y2=ln[0][1]+(m*(xmax-ln[0][0])) ;   //right intercept
    x2=ln[0][0]+((ymin-ln[0][1])/m);      //bottom intercept
    st[0][0]=xmax;                       //storing right-intercept co-ordinate
    st[0][1]=y2;
    st[1][0]=x2;                         //storing bottom-intercept co-ordinate
    st[1][1]=ymin;
    cout<<"\nRight intercept:";
    cout<<st[0][0]<<","<<st[0][1];
    cout<<"\nBottom intercept:";
    cout<<st[1][0]<<","<<st[1][1];
     cout<<"\n\nVisible portion of the line is:";
    for(i=0;i<2;i++)
      {
      if(((st[i][0]>=xmin)&&(st[i][0]<=xmax))&&((st[i][1]>=ymin)&&(st[i][1]<=ymax)))
{
       final1[i][0]=st[i][0];
       final1[i][1]=st[i][1];
   print[0][0]=st[i][0];
print[0][1]=st[i][1];
       cout<<"("<<final1[i][0]<<","<<final1[i][1]<<")";
}
      }
    cout<<" to ("<<ln[0][0]<<","<<ln[0][1]<<")";
    setcolor(GREEN);
       line(print[0][0],print[0][1],ln[0][0],ln[0][1]);
    goto Label1;
    }

    if(bit2[3]==1 && bit2[2]==0 && bit2[1]==1 && bit2[0]==0)
    {
    y2=ln[0][1]+(m*(xmax-ln[0][0])) ;   //right intercept
    x1=ln[0][0]+((ymax-ln[0][1])/m);      //top intercept
    st[0][0]=xmax;                       //storing right-intercept co-ordinate
    st[0][1]=y2;
    st[1][0]=x1;                         //storing top-intercept co-ordinate
    st[1][1]=ymax;
    cout<<"\nRight intercept:";
    cout<<st[0][0]<<","<<st[0][1];
    cout<<"\nTop intercept:";
    cout<<st[1][0]<<","<<st[1][1];
     cout<<"\n\nVisible portion of the line is:";
    for(i=0;i<2;i++)
      {
      if(((st[i][0]>=xmin)&&(st[i][0]<=xmax))&&((st[i][1]>=ymin)&&(st[i][1]<=ymax)))
{
       final1[i][0]=st[i][0];
       final1[i][1]=st[i][1];
   print[0][0]=st[i][0];
print[0][1]=st[i][1];
       cout<<"("<<final1[i][0]<<","<<final1[i][1]<<")";
}
      }
    cout<<" to ("<<ln[0][0]<<","<<ln[0][1]<<")";
    setcolor(GREEN);
       line(print[0][0],print[0][1],ln[0][0],ln[0][1]);
    goto Label1;
    }

      if(bit2[3]==1 && bit2[2]==0 && bit2[1]==0 && bit2[0]==1)
    {
    y1=ln[0][1]+(m*(xmin-ln[0][0])) ;   //left intercept
    x1=ln[0][0]+((ymax-ln[0][1])/m);      //top intercept
    st[0][0]=xmin;                       //storing left-intercept co-ordinate
    st[0][1]=y1;
    st[1][0]=x1;                         //storing top-intercept co-ordinate
    st[1][1]=ymax;
    cout<<"\nLeft intercept:";
    cout<<st[0][0]<<","<<st[0][1];
    cout<<"\nTop intercept:";
    cout<<st[1][0]<<","<<st[1][1];
     cout<<"\n\nVisible portion of the line is:";
    for(i=0;i<2;i++)
      {
      if(((st[i][0]>=xmin)&&(st[i][0]<=xmax))&&((st[i][1]>=ymin)&&(st[i][1]<=ymax)))
{
       final1[i][0]=st[i][0];
       final1[i][1]=st[i][1];
    print[0][0]=st[i][0];
print[0][1]=st[i][1];
       cout<<"("<<final1[i][0]<<","<<final1[i][1]<<")";
}
      }
    cout<<" to ("<<ln[0][0]<<","<<ln[0][1]<<")";
       setcolor(GREEN);
       line(print[0][0],print[0][1],ln[0][0],ln[0][1]);
    goto Label1;
    }
    }
}   //else close
Label1:
cout<<"\n\nDo You Wanna Continue(Y/N):-";
cin>>ch;
}  //while close
closegraph();
}                             

                                           OUTPUT