CLIP_LIN.C

/* This is a program in C to demonstrate 2D clipping using Cohen-Sutherland line clipping */
#include<conio.h>
#include<stdio.h>
#include<math.h>
#include<graphics.h>

void main()
{
int rcode_begin[4]={0,0,0,0},rcode_end[4]={0,0,0,0},region_code[4];
int W_xmax,W_ymax,W_xmin,W_ymin,flag=0;
float slope;
int x,y,x1,y1,i, xc,yc;

int gd=DETECT,gm;
initgraph(&gd,&gm,"C:\\TURBOC3\\BGI");

printf("\n****** Cohen Sutherland Line Clipping algorithm ***********");
printf("\n Now, enter XMin, YMin =");
scanf("%d %d",&W_xmin,&W_ymin);
printf("\n First enter XMax, YMax =");
scanf("%d %d",&W_xmax,&W_ymax);
printf("\n Please enter intial point x and y= ");
scanf("%d %d",&x,&y);
printf("\n Now, enter final point x1 and y1= ");
scanf("%d %d",&x1,&y1);
cleardevice();
//before clipping
rectangle(W_xmin,W_ymin,W_xmax,W_ymax);
line(x,y,x1,y1);

if(y>W_ymax)
{
	rcode_begin[0]=1;	   // Top
	flag=1 ;
}
if(y<W_ymin)
{
	rcode_begin[1]=1;           // Bottom
	flag=1;
}
if(x>W_xmax)
{
	rcode_begin[2]=1;           // Right
	flag=1;
}
if(x<W_xmin)
{
	rcode_begin[3]=1;           //Left
	flag=1;
}

//end point of Line
if(y1>W_ymax)
{
	rcode_end[0]=1;           // Top
	flag=1;
}
if(y1<W_ymin)
{
	rcode_end[1]=1;           // Bottom
	flag=1;
}
if(x1>W_xmax)
{
	rcode_end[2]=1;           // Right
	flag=1;
}
if(x1<W_xmin)
{
	rcode_end[3]=1;           //Left
	flag=1;
}
if(flag==0)
{
	printf("No need of clipping as it is already in window");
}
flag=1;
for(i=0;i<4;i++)
{
	region_code[i]= rcode_begin[i] && rcode_end[i] ;
	if(region_code[i]==1)
	flag=0;
}
if(flag==0)
{
	printf("\n Line is completely outside the window");
}
else
{
	slope=(float)(y1-y)/(x1-x);
	if(rcode_begin[2]==0 && rcode_begin[3]==1)   //left
{
	y=y+(float) (W_xmin-x)*slope ;
	x=W_xmin;

}
if(rcode_begin[2]==1 && rcode_begin[3]==0)       // right
{
	y=y+(float) (W_xmax-x)*slope ;
	x=W_xmax;
}
if(rcode_begin[0]==1 && rcode_begin[1]==0)      // top
{
	x=x+(float) (W_ymax-y)/slope ;
	y=W_ymax;
}
if(rcode_begin[0]==0 && rcode_begin[1]==1)     // bottom
{
	x=x+(float) (W_ymin-y)/slope ;
	y=W_ymin;
}
// end points
if(rcode_end[2]==0 && rcode_end[3]==1)   //left
{
	y1=y1+(float) (W_xmin-x1)*slope ;
	x1=W_xmin;
}
if(rcode_end[2]==1 && rcode_end[3]==0)       // right
{
	y1=y1+(float) (W_xmax-x1)*slope ;
	x1=W_xmax;
}
if(rcode_end[0]==1 && rcode_end[1]==0)      // top
{
	x1=x1+(float) (W_ymax-y1)/slope ;
	y1=W_ymax;
}
if(rcode_end[0]==0 && rcode_end[1]==1)     // bottom
{
	x1=x1+(float) (W_ymin-y1)/slope ;
	y1=W_ymin;
}
}
outtext("Before Clipping");
getch();
clearviewport();
//after clipping
outtext("After clipping");
rectangle(W_xmin,W_ymin,W_xmax,W_ymax);
setcolor(RED);
line(x,y,x1,y1);
getch();
closegraph();
}