Computer Graphics (CG) :Write C++ program to implement Cohen Southerland line clipping algorithm.

 

Computer Graphics Assignment 2

Write C++ program to implement Cohen Southerland line clipping algorithm.

Code :

#include<iostream>

#include<stdlib.h>

#include<math.h>

#include<graphics.h>

#include<dos.h>

using namespace std;

class Coordinate

{

public:

int x,y;

char code[4];

};

class Lineclip

{

public:

Coordinate PT;

void drawwindow();

void drawline(Coordinate p1,Coordinate p2);

Coordinate setcode(Coordinate p);

int visibility(Coordinate p1,Coordinate p2);

Coordinate resetendpt(Coordinate p1,Coordinate p2);

};

int main()

{

Lineclip lc;

int gd = DETECT,v,gm;

Coordinate p1,p2,p3,p4,ptemp;

cout<<"\n Enter x1 and y1\n";

cin>>p1.x>>p1.y;

cout<<"\n Enter x2 and y2\n";

cin>>p2.x>>p2.y;

initgraph(&gd,&gm,"");

lc.drawwindow();

delay(2000);

lc.drawline (p1,p2);

delay(2000);

cleardevice();

delay(2000);

p1=lc.setcode(p1);

p2=lc.setcode(p2);

v=lc.visibility(p1,p2);

delay(2000);

switch(v)

{

case 0: lc.drawwindow();

delay(2000);

lc.drawline(p1,p2);

break;

    case 1:lc.drawwindow();

        delay(2000);

        break;

    case 2:p3=lc.resetendpt(p1,p2);

         p4=lc.resetendpt(p2,p1);

         lc.drawwindow();

         delay(2000);

         lc.drawline(p3,p4);

         break;

    }

     delay(2000);

     closegraph();

 }

 

 

 void Lineclip::drawwindow()

 {

  line(150,100,450,100);

  line(450,100,450,350);

  line(450,350,150,350);

  line(150,350,150,100);

 

 }

 

 void Lineclip::drawline(Coordinate p1,Coordinate p2)

 {

  line(p1.x,p1.y,p2.x,p2.y);

 }

Coordinate Lineclip::setcode(Coordinate p)

{

Coordinate 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)

ptemp.code[3]='1';

else

ptemp.code[3]='0';

ptemp.x=p.x;

ptemp.y=p.y;

return(ptemp);

};

int Lineclip:: visibility(Coordinate p1,Coordinate p2)

{

int i,flag=0;

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

{

if(p1.code[i]!='0' || (p2.code[i]=='1'))

  flag='0';

}

if(flag==0)

return(0);

 

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

{

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

flag='0';

}

if(flag==0)

return(1);

return(2);

}

Coordinate Lineclip::resetendpt(Coordinate p1,Coordinate p2)

{

Coordinate 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[1]=='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);

}

Input :

X1 , Y1:

100

200

X2, Y2 :

500

100

Output :