LINE CLIPPING USING LIANG-BARSKY METHOD

#include<stdio.h>
#include<conio.h>
#include<graphics.h>
#include<math.h>
void main()
{
int gd = DETECT,gmode;
int i,x1,y1,x2,y2,xmin,xmax,ymin,ymax,xx1,xx2,yy1,yy2;
float t1,t2,p[4],q[4],temp;
initgraph(&gd,&gmode,"C://TurboC3/BGI");
/*x1 = 100;
y1 = 200;
x2 = 300;
y2 = 380;
*/
printf("Enter the end points of your line\n");
scanf("%d%d%d%d",&x1,&y1,&x2,&y2);
xmin = 150;
xmax = 350;
ymin = 150;
ymax = 350;
//line(x1,y1,x2,y2);
rectangle(xmin,ymin,xmax,ymax);
p[0] = -(x2-x1);
p[1] = (x2-x1);
p[2] = -(y2-y1);
p[3] = (y2-y1);

q[0] = (x1-xmin);
q[1] = (xmax-x1);
q[2] = (y1-ymin);
q[3] = (ymax-y1);

for (i = 0; i < 4; i++)
{
if (p[i] == 0)
{
printf("Line is parallel to one of the clipping boundary\n");
if (q[i]>=0)
{
if (i<2)
{
if (y1<ymin)
{
y1 = ymin;
}
if (y2>ymax)
{
y2 = ymax;
}
line(x1,y1,x2,y2);
}
if (i>1)
{
if (x1<xmin)
{
x1 = xmin;
}
if (x2>xmax)
{
x2 = xmax;
}
line(x1,y1,x2,y2);
}
}
getch();
}
}
t1 = 0;
t2 = 1;
for (i = 0; i < 4; i++)
{
temp = q[i]/p[i];
if(p[i]<0)
{
if (t1<=temp)
{
t1 = temp;
}
}
else
{
if (t2>temp)
{
t2 = temp;
}
}
}
if (t1<t2)
{
xx1 = x1 + t1*p[1];
xx2 = x1 + t2*p[1];
yy1 = y1 + t1*p[3];
yy2 = y1 + t2*p[3];
line(xx1,yy1,xx2,yy2);
}
getch();
}

OUPUT:-

Before clipping:

After clipping: