Write a programme of Cohen Sutherland Line clipping Algorithm in C.

 Cohen Sutherland Line clipping Algorithm

#include<stdio.h>

#include<stdlib.h>

#include<math.h>

#include<graphics.h>

#include<dos.h>

#include<conio.h>

typedef struct coordinate

{

    int x,y;

    char code[4];

}PT;

void drawwindow();

void drawline(PT p1,PT p2);

PT setcode(PT p);

int visibility(PT p1,PT p2);

PT resetendpt(PT p1,PT p2);

void main()

{

    int gd=DETECT,v,gm;

    PT p1,p2,p3,p4,ptemp;

   printf("\n\tEnter x1 and y1\n");

    scanf("%d %d",&p1.x,&p1.y);

    printf("\n\tEnter x2 and y2\n");

    scanf("%d %d",&p2.x,&p2.y);

   initgraph(&gd,&gm,"c:\\turboc3\\bgi");

    drawwindow();

    delay(500);

  drawline(p1,p2);

    delay(500);

    cleardevice();

   delay(500);

    p1=setcode(p1);

    p2=setcode(p2);

    v=visibility(p1,p2);

    delay(500);

   switch(v)

    {

    case 0: drawwindow();

                delay(500);

                drawline(p1,p2);

                break;

    case 1:    drawwindow();

                delay(500);

                break;

    case 2:    p3=resetendpt(p1,p2);

                p4=resetendpt(p2,p1);

                drawwindow();

                delay(500);

                drawline(p3,p4);

                break;

    }

   delay(5000);

    closegraph();

    getch();

}

void drawwindow()

{

    line(150,100,450,100);

    line(450,100,450,350);

    line(450,350,150,350);

    line(150,350,150,100);

}

void drawline(PT p1,PT p2)

{

    line(p1.x,p1.y,p2.x,p2.y);

}

PT setcode(PT p)    //for setting the 4 bit code

{

    PT ptemp;

 

    if(p.y<100)

            ptemp.code[0]='1';    //Top

    else

            ptemp.code[0]='0';

 

    if(p.y>350)

            ptemp.code[1]='1';    //Bottom

    else

            ptemp.code[1]='0';

 

    if(p.x>450)

            ptemp.code[2]='1';    //Right

    else

            ptemp.code[2]='0';

 

    if(p.x<150)

            ptemp.code[3]='1';    //Left

    else

            ptemp.code[3]='0';

 

    ptemp.x=p.x;

    ptemp.y=p.y;

   return(ptemp);

}

int visibility(PT p1,PT p2)

{

    int i,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;

    int x,y,i;

    float m,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);

}

 

 Output :-