Program of cohen sutherland Line clipping Algorithm

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

int pixels[2][4];
float xn1,xn2,yn1,yn2,x3,y3,m;


void show_quadrant()
    {
    cleardevice();
    rectangle(120,40,320,240);
    rectangle(320,40,520,240);
    rectangle(120,240,320,440);
    rectangle(320,240,520,440);
    for(int i=130;i<=510;i+=10)
        {
        if(i==320)
        continue;
        outtextxy(i,237,\"+\");
        }
    for(i=50;i<=430;i+=10)
        {
        if(i==240)
        continue;
        outtextxy(317,i,\"-\");
        }
    outtextxy(310,230,\"O\");
    outtextxy(530,240,\"X\");
    outtextxy(320,450,\"-Y\");
    outtextxy(100,240,\"-X\");
    outtextxy(320,30,\"Y\");
    }

void su_co(int x1,int y1,int x2,int y2,int xmin,int ymin,int xmax,int ymax)
       {
          int i,j,fl;
          for(i=0;i<2;i++)
              for(j=0;j<4;j++)
                 pixels[i][j]=0;
          if(y1>ymax)
        pixels[0][0]=1;
          if(y1<ymin)
        pixels[0][1]=1;
          if(x1>xmax)
        pixels[0][2]=1;
          if(x1<xmin)
        pixels[0][3]=1;
          if(y2>ymax)
        pixels[1][0]=1;
          if(y2<ymin)
        pixels[1][1]=1;
          if(x2>xmax)
        pixels[1][2]=1;
          if(x2<xmin)
        pixels[1][3]=1;

          for(j=0;j<4;j++)
              {
         if(pixels[0][j]==0&&pixels[1][j]==0)
            continue;
        if(pixels[0][j]==1&&pixels[1][j]==1)
              {
                fl=3;
                break;
              }
        fl=2;
              }
          switch(fl)
        {
           case 1:
                        line(320+x1,240-y1,320+x2,240-y2);
                 break;

           case 3:
                 cout<<\"\\n\\n\\a\\\" Line Is Not Visible...:-(\";
                 break;

           case 2:
                 m=(y2-y1)/(x2-x1);
                 xn1=x1;
            yn1=y1;
                 xn2=x2;
            yn2=y2;
            if(pixels[0][0]==1)
                       {
                  xn1=x1+(ymax-y1)/m;
                  yn1=ymax;
                       }
                 if(pixels[0][1]==1)
                       {
                  xn1=x1+(ymin-y1)/m;
                  yn1=ymin;
                       }
                 if(pixels[0][2]==1)
                       {
                  yn1=y1+(xmax-x1)*m;
                  xn1=xmax;
                       }
                 if(pixels[0][3]==1)
                       {
                  yn1=y1+(xmin-x1)*m;
                  xn1=xmin;
                       }
                 if(pixels[1][0]==1)
                       {
                  xn2=x2+(ymax-y2)/m;
                  yn2=ymax;
                       }
                 if(pixels[1][1]==1)
                       {
                  xn2=x2+(ymin-y2)/m;
                  yn2=ymin;
                       }
                 if(pixels[1][2]==1)
                       {
                  yn2=y2+(xmax-x2)*m;
                  xn2=xmax;
                       }
                 if(pixels[1][3]==1)
                       {
                  yn2=y2+(xmin-x2)*m;
                  xn2=xmin;
                       }
                 line(320+xn1,240-yn1,320+xn2,240-yn2);
                 break;
        }
       }


void midpt(int x1,int y1,int x2,int y2,int xmin,int ymin,int xmax,int ymax)
       {
          int fl=1;
          int i,j;
         int ox1=x1,ox2=x2,oy1=y1,oy2=y2;
          for(i=0;i<2;i++)
         for(j=0;j<4;j++)
                 pixels[i][j]=0;

          if(y1>ymax)
        pixels[0][0]=1;
          if(y1<ymin)
        pixels[0][1]=1;
          if(x1>xmax)
        pixels[0][2]=1;
          if(x1<xmin)
        pixels[0][3]=1;
          if(y2>ymax)
        pixels[1][0]=1;
          if(y2<ymin)
        pixels[1][1]=1;
          if(x2>xmax)
        pixels[1][2]=1;
          if(x2<xmin)
        pixels[1][3]=1;

          for(j=0;j<4;j++)
              {
         if(pixels[0][j]==0&&pixels[1][j]==0)
            continue;

         if(pixels[0][j]==1&&pixels[1][j]==1)
              {
                fl=3;
                break;
              }
        fl=2;
              }
          switch(fl)
              {
           case 1:
                 line(320+x1,240-y1,320+x2,240-y2);
                 break;

           case 3:
                 cout<<\"\\n\\n\\a\\\" Line Is Not Visible...:-(\";
                 break;

           case 2:
                 xn1=x1;
            yn1=y1;
                 xn2=x2;
            yn2=y2;
                 fl=0;
                 x3=x1;
            y3=y1;
                 while(1)
                       {
     if(!(y1>ymax || y1<ymin || x1>xmax || x1<xmin) && (x3 || y3)!=0.1)
                    break;
                 x3=(x1+x2)/2;
                 y3=(y1+y2)/2;
     if(!(y3>ymax || y3<ymin || x3>xmax || x3<xmin))
                   fl=1;
                 else
                   fl=0;
                 if(fl)
                       {
                          x2=x3;
                          y2=y3;
                       }
                 else
                       {
                          x1=x3;
                          y1=y3;
                       }
                       }
                 xn1=x3;
                 yn1=y3;
                 fl=0;
                 x1=ox1;
                 x2=ox2;
                 y1=oy1;
                 y2=oy2;
                 x3=x2;
            y3=y2;
                 while(1)
                       {
     if(!(y2>ymax || y2<ymin || x2>xmax || x2<xmin) && (x3 || y3)!=0.1)
                    break;
                 x3=(x1+x2)/2;
                 y3=(y1+y2)/2;

     if(!(y3>ymax || y3<ymin || x3>xmax || x3<xmin))
                   fl=1;
                 else
                   fl=0;

                 if(fl)
                       {
                          x1=x3;
                          y1=y3;
                       }
                 else
                       {
                          x2=x3;
                          y2=y3;
                       }
                 }
             xn2=x3;
                 yn2=y3;
                 line(320+xn1,240-yn1,320+xn2,240-yn2);
                 break;
         }
       }

void show_message()
    {
    char *mess[]={\"-\",\"=\",\"[\",\" \",\"L\",\"i\",\"n\",\"e\",\" \",\"C\",\"l\",\"i\",
              \"p\",\"p\",\"i\",\"n\",\"g\",\" \",\"]\",\"=\",\"-\",};
    int xx=29,xxx=50,i,j;
    _setcursortype(_NOCURSOR);
    for(i=0,j=21;i<13,j>=11;i++,j--)
        {
        gotoxy(xx,1);
        cout<<mess[i];
        xx++;
        gotoxy(xxx,1);
        cout<<mess[j];
        xxx--;
        delay(50);
        }
    _setcursortype(_NORMALCURSOR);
    }


void main()
    {
    clrscr();
        int gd=DETECT,gm,i,j;
        int xmin,ymin,xmax,ymax,x1,y1,x2,y2;
        int choice,ed[20],num;
        show_message();
        cout<<\"\\n\\n\\t\\t\\\" Enter The Co-Ordinates Of The Clipping Window.\\\"\";
    cout<<\"\\n\\n\\t\\t\\\" Enter X(min) & Y(min) \\\":=\";
        cin>>xmin>>ymin;
    cout<<\"\\n\\t\\t\\\" Enter X(max) & Y(max) \\\":=\";
        cin>>xmax>>ymax;

        cout<<\"\\n\\t\\t\\\" Enter The Co-Ordinates Of The Line.\\\"\";
    cout<<\"\\n\\n\\t\\t\\\" Enter X(1) & Y(1) \\\":=\";
        cin>>x1>>y1;
    cout<<\"\\n\\t\\t\\\" Enter X(2) & Y(2) \\\":=\";
        cin>>x2>>y2;
        clrscr();
        show_message();
    cout<<\"\\n\\n\\n\\t\\t1:==>\\\" Sutherland-Cohen \\\"\";
    cout<<\"\\n\\n\\t\\t2:==>\\\" Mid-Point Method \\\"\";
    cout<<\"\\n\\n\\t\\t3:==>\\\" Exit \\\"\";
    cout<<\"\\n\\n\\t\\t\\\" Enter Your Choice \\\":=\";
    cin>>choice;
    switch(choice)
        {
        case 1:
            initgraph(&gd,&gm,\"..\\\\bgi\");
            clearviewport();
                show_quadrant();
                  line(320+xmin,240-ymin,320+xmin,240-ymax);
                  line(320+xmin,240-ymax,320+xmax,240-ymax);
                  line(320+xmax,240-ymax,320+xmax,240-ymin);
                  line(320+xmax,240-ymin,320+xmin,240-ymin);
            line (320+x1,240-y1,320+x2,240-y2);
                getch();
                cleardevice();
                show_quadrant();
                  line(320+xmin,240-ymin,320+xmin,240-ymax);
                  line(320+xmin,240-ymax,320+xmax,240-ymax);
                  line(320+xmax,240-ymax,320+xmax,240-ymin);
                  line(320+xmax,240-ymin,320+xmin,240-ymin);
            su_co(x1,y1,x2,y2,xmin,ymin,xmax,ymax);
            getch();
            break;

        case 2:
            initgraph(&gd,&gm,\"..\\\\bgi\");
            clearviewport();
                show_quadrant();
                  line(320+xmin,240-ymin,320+xmin,240-ymax);
                  line(320+xmin,240-ymax,320+xmax,240-ymax);
                  line(320+xmax,240-ymax,320+xmax,240-ymin);
                  line(320+xmax,240-ymin,320+xmin,240-ymin);
            line (320+x1,240-y1,320+x2,240-y2);
                getch();
                cleardevice();
                show_quadrant();
                  line(320+xmin,240-ymin,320+xmin,240-ymax);
                  line(320+xmin,240-ymax,320+xmax,240-ymax);
                  line(320+xmax,240-ymax,320+xmax,240-ymin);
                  line(320+xmax,240-ymin,320+xmin,240-ymin);
               midpt(x1,y1,x2,y2,xmin,ymin,xmax,ymax);
            getch();
            break;

        case 3:
            exit(0);

                default:
                    cout<<\"\\n\\t\\a\\\" Press A Valid Key...!!! \\\"\";
                        getch();
                        main();
                        break;
        }
    closegraph();
        }