tw5.c

#include<stdio.h>
#include<GL/glut.h>
#define outcode int
double xmin=50,ymin=50,xmax=100,ymax=100;
double xvmin=200,yvmin=200,xvmax=300,yvmax=300;

double x0,y0,x1,y1;
const int RIGHT=8;
const int LEFT=2;
const int TOP=4;
const int BOTTOM=1;
outcode ComputeOutCode(double x,double y);
void CohenSutherland(double x0,double y0,double x1,double y1)
{
	outcode outcode0,outcode1,outcodeOut;
	int accept,done;
	accept=0;
	done=0;
	outcode0=ComputeOutCode(x0,y0);
	outcode1=ComputeOutCode(x1,y1);
	do
	{
		if(!(outcode0|outcode1))
		{
			accept=1;
			done=1;
		}
		else if(outcode0&outcode1)
			done=1;
		else
		{
			double x,y;
			outcodeOut=outcode0? outcode0:outcode1;
			if(outcodeOut&TOP)
			{
				x=x0+(x1-x0)*(ymax-y0)/(y1-y0);
				y=ymax;
			}	
			else if(outcodeOut&BOTTOM)
			{
				x=x0+(x1-x0)*(ymin-y0)/(y1-y0);
				y=ymin;
			}
			else if(outcodeOut&RIGHT)
			{
				y=y0+(y1-y0)*(xmax-x0)/(x1-x0);
				x=xmax;
			}
			else
			{
				y=y0+(y1-y0)*(xmin-x0)/(x1-x0);
				x=xmin;
				}
			if(outcodeOut==outcode0)
			{
				x0=x;
				y0=y;
				outcode0=ComputeOutCode(x0,y0);
			}
			else
			{
				x1=x;
				y1=y;
				outcode1=ComputeOutCode(x1,y1);
			}
		}
	}while(!done);
	if(accept)
	{
		double sx=(xvmax-xvmin)/(xmax-xmin);
		double sy=(yvmax-yvmin)/(ymax-ymin);
		double vx0=xvmin+(x0-xmin)*sx;
		double vy0=yvmin+(y0-ymin)*sy;
		double vx1=xvmin+(x1-xmin)*sx;
		double vy1=yvmin+(y1-ymin)*sy;
		glColor3f(1.0,0.0,0.0);
		glBegin(GL_LINE_LOOP);
			glVertex2f(xvmin,yvmin);
			glVertex2f(xvmax,yvmin);
			glVertex2f(xvmax,yvmax);
			glVertex2f(xvmin,yvmax);
		glEnd();
		glColor3f(0.0,0.0,1.0);
		glBegin(GL_LINES);
			glVertex2d(vx0,vy0);
			glVertex2d(vx1,vy1);
		glEnd();
	}
}
outcode ComputeOutCode(double x,double y)
{
	outcode code=0;
	if(y>ymax)
		code=TOP;
	else if(y<ymin)
		code=BOTTOM;
	if(x>xmax)
		code=RIGHT;
	else if(x<xmin)
		code=LEFT;
	return code;
}
void display()
{
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(1.0,0.0,0.0);
	glBegin(GL_LINES);
		glVertex2d(x0,y0);
		glVertex2d(x1,y1);
	glEnd();
	glColor3f(0.0,0.0,1.0);
	glBegin(GL_LINE_LOOP);
			glVertex2f(xmin,ymin);
			glVertex2f(xmax,ymin);
			glVertex2f(xmax,ymax);
			glVertex2f(xmin,ymax);
	glEnd();
	CohenSutherland(x0,y0,x1,y1);
	glFlush();
}		
void myinit()
{
	glClearColor(1.0,1.0,1.0,1.0);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluOrtho2D(0.0,499.0,0.0,499.0);
}
void main(int argc,char **argv)
{	printf("Enter the end points of the line: ");
	scanf("%lf%lf%lf%lf",&x0,&y0,&x1,&y1);
	glutInit(&argc,argv);
	glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
	glutInitWindowSize(500,500);
	glutInitWindowPosition(0,0);
	glutCreateWindow("Cohen-Sutherland Line Clipping");
	glutDisplayFunc(display);
	myinit();
	glutMainLoop();
}