Program to implement Cohen-Sutherland Line Clipping Algorithm.

/*program to implement Cohen-Sutherland Line Clipping Algorithm*/

#include stdio.h
#include conio.h
#include graphics.h
#include dos.h
#include math.h
#include stdlib.h

typedef struct coordinates
{
int x;
int y;
char code[4];
}pt;

pt p1,p2,ptemp;

void drawwindow();
void drawline(pt p1,pt p2, int c1);
pt setcode(pt p);
int visibility(pt p1,pt p2);
pt resetendpt(pt p1,pt p2);

void main()
{
int gd=DETECT,gm,v;

detectgraph(&gd,&gm);
initgraph(&gd,&gm,"c:\\tc\\bgi");
cleardevice();
printf("\nEnter the endpoint 1\t");
scanf("%d %d",&p1.x,&p1.y);
printf("\nEnter the endpoint 2\t");
scanf("%d %d",&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();
drawwindow();
drawline(p1,p2,15);
break;
}
case 1:
{
cleardevice();
drawwindow();
break;
}
case 2:
{
cleardevice();
p1=resetendpt(p1,p2);
p2=resetendpt(p2,p1);
drawwindow();
drawline(p1,p2,15);
break;
}
}
getch();
closegraph();
}

void drawwindow()
{
setcolor(RED);
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, int c1)
{
setcolor(c1);
line(p1.x,p1.y,p2.x,p2.y);
}

pt setcode(pt p)
{
pt ptemp;
if(p.y>350)
ptemp.code[0]='1';
else
ptemp.code[0]='0';
if(p.y<100) 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 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=(float)(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);
}