Cohen Sutherland line clipping algorithm in c
The Cohen-Sutherland algorithm is a computer graphics algorithm used for line clipping. The algorithm divides a two-dimensional space into 9 regions (or a three-dimensional space into 27 regions), and then efficiently determines the lines and portions of lines that are visible in the center region of interest (the viewport).The Cohen–Sutherland algorithm can be used only on a rectangular clipping area.
IMPLEMENTATION IN C
#include<stdio.h>
#include<graphics.h>
#include<conio.h>
typedef unsigned int outcode;
enum { TOP=0x1, BOTTOM=0x2, RIGHT=0x4, LEFT=0x8 };
void lineclip(x0,y0,x1,y1,xwmin,ywmin,xwmax,ywmax )
float x0,y0,x1,y1,xwmin,ywmin,xwmax,ywmax;
{
int gd,gm;
outcode code0,code1,codeout;
int accept = 0, done=0;
code0 = calcode(x0,y0,xwmin,ywmin,xwmax,ywmax);
code1 = calcode(x1,y1,xwmin,ywmin,xwmax,ywmax);
do{
if(!(code0 | code1))
{ accept =1 ; done =1; }
else
if(code0 & code1) done = 1;
else
{
float x,y;
codeout = code0 ? code0 : code1;
if(codeout & TOP)
{
x = x0 + (x1-x0)*(ywmax-y0)/(y1-y0);
y = ywmax;
}
else
if( codeout & BOTTOM)
{
x = x0 + (x1-x0)*(ywmin-y0)/(y1-y0);
y = ywmin;
}
else
if ( codeout & RIGHT)
{
y = y0+(y1-y0)*(xwmax-x0)/(x1-x0);
x = xwmax;
}
else
{
y = y0 + (y1-y0)*(xwmin-x0)/(x1-x0);
x = xwmin;
}
if( codeout == code0)
{
x0 = x; y0 = y;
code0=calcode(x0,y0,xwmin,ywmin,xwmax,ywmax);
}
else
{
x1 = x; y1 = y;
code1 = calcode(x1,y1,xwmin,ywmin,xwmax,ywmax);
}
}
} while( done == 0);
if(accept) line(x0,y0,x1,y1);
rectangle(xwmin,ywmin,xwmax,ywmax);
getch();
}
int calcode (x,y,xwmin,ywmin,xwmax,ywmax)
float x,y,xwmin,ywmin,xwmax,ywmax;
{
int code =0;
if(y> ywmax)
code |=TOP;
else if( y<ywmin)
code |= BOTTOM;
else if(x > xwmax)
code |= RIGHT;
else if ( x< xwmin)
code |= LEFT;
return(code);
}
main()
{
float x2,y2,x1,y1,xwmin,ywmin,xwmax,ywmax;
int gd=DETECT,gm;
clrscr();
initgraph(&gd,&gm,"e:\\tc\\bgi");
printf("\n\n\tEnter the co-ordinates of Line :");
printf("\n\n\tX1 Y1 : ");
scanf("%f %f",&x1,&y1);
printf("\n\n\tX2 Y2 : ");
scanf("%f %f",&x2,&y2);
printf("\n\tEnter the co_ordinates of window :\n ");
printf("\n\txwmin , ywmin : ");
scanf("%f %f",&xwmin,&ywmin);
printf("\n\txwmax , ywmax : ");
scanf("%f %f",&xwmax,&ywmax);
clrscr();
line(x1,y1,x2,y2);
rectangle(xwmin,ywmin,xwmax,ywmax);
getch();
clrscr();
lineclip(x1,y1,x2,y2,xwmin,ywmin,xwmax,ywmax );
getch();
closegraph();
}