Program for implementation of Cohen –Sutherland Line clipping algorithm.

#include <conio.h>

#include <iostream.h>

#include <graphics.h>

typedefstruct coordinate

                {

                intx,y;

                char code[4];

                }PT;

voiddrawwindow();

voiddrawline (PT p1,PT p2,int cl);

PT setcode(PT p);

int visibility (PT p1,PT p2);

PT resetendpt (PT p1,PT p2);

main()

                {

                intgd=DETECT, gm,v;

                PT p1,p2,ptemp;

                initgraph(&gd,&gm,"C:\\TurboC3\\bgi");

                cleardevice();

                cout<<"\n\n\t\tENTER END-POINT 1 (x,y): ";

                cin>>p1.x>>p1.y;

                cout<<"\n\n\t\tENTER END-POINT 2 (x,y): ";

                cin>>p2.x>>p2.y;

                cleardevice();

                drawwindow();

                getch();

                drawline(p1,p2,15);

                getch();

                p1=setcode(p1);

                p2=setcode(p2);

                v=visibility(p1,p2);

                switch(v)

                                {

                                case 0:

                                                cleardevice();    /* Line conpletely visible */

                                                drawwindow();

                                                drawline(p1,p2,15);

                                                break;

                                case 1:

                                                cleardevice();    /* Line completely invisible */

                                                drawwindow();

                                                break;

                                case 2: cleardevice();      /* line partly visible */

                                                p1=resetendpt (p1,p2);

                                                p2=resetendpt(p2,p1);

                                                drawwindow();

                                                drawline(p1,p2,15);

                                                break;

                                }

                getch();

                closegraph();

                return(0);

                }

voiddrawwindow()

                {

                setcolor(RED);

                line(150,100,450,100);

                line(450,100,450,350);

                line(450,350,150,350);

                line(150,350,150,100);

                }

voiddrawline (PT p1,PT p2,int cl)

                {

                setcolor(cl);

                line(p1.x,p1.y,p2.x,p2.y);

                }

PT setcode(PT p)

                {

                PT ptemp;

                if(p.y<100)

                                ptemp.code[0]='1';

                else

                                ptemp.code[0]='0';

                if(p.y>350)

                                ptemp.code[1]='1';

                else

                                ptemp.code[1]='0';

                if (p.x>450)

                                ptemp.code[2]='1';

                else

                                ptemp.code[2]='0';

                if (p.x<150) /* LEFT */

                                ptemp.code[3]='1';

                else

                                ptemp.code[3]='0';

                ptemp.x=p.x;

                ptemp.y=p.y;

                return(ptemp);

                }

int visibility (PT p1,PT p2)

                {

                inti,flag=0;

                for(i=0;i<4;i++)

                                {

                                if((p1.code[i]!='0')||(p2.code[i]!='0'))

                                flag=1;

                                }

                if(flag==0)

                                return(0);

                for(i=0;i<4;i++)

                                {

                                if((p1.code[i]==p2.code[i]) &&(p1.code[i]=='1'))

                                flag=0;

                                }

                if(flag==0)

                                return(1);

                return(2);

                }

PT resetendpt (PT p1,PT p2)

                {

                PT temp;

                intx,y,i;

                floatm,k;

                if( p1.code[3]=='1')

                                x=150;

                if(p1.code[2]=='1')

                                x=450;

                if((p1.code[3]=='1')||(p1.code[2]=='1'))

                                {

                                m=(float) (p2.y-p1.y)/(p2.x-p1.x);

                                k=(p1.y+(m*(x-p1.x)));

                                temp.y=k;

                                temp.x=x;

                                for(i=0;i<4;i++)

                                                temp.code[i]=p1.code[i];

                                if(temp.y<=350&&temp.y>=100)

                                                return(temp);

                                }

                if(p1.code[0]=='1')

                                y=100;

                if(p1.code [1]=='1')

                                y=350;

                if((p1.code[0]=='1')||(p1.code[1]=='1'))

                                {

                                m=(float)(p2.y-p1.y)/(p2.x-p1.x);

                                k=(float)p1.x+(float)(y-p1.y)/m;

                                temp.x=k;

                                temp.y=y;

                                for(i=0;i<4;i++)

                                                temp.code[i]=p1.code[i];

                                return(temp);

                                }

                else

                                return(p1);

                }