#include <GL/glut.h> 

void display() 
{       
	glClearColor(1, 1, 1, 1);            
	glClear(GL_COLOR_BUFFER_BIT);  
	glColor3ub(255, 0, 0); 	   
	glBegin(GL_LINES);		
		glVertex2i(-80, -60);
		glVertex2i( 40,  40);
	glEnd();            
	glFlush();      
} 

int main(int argc, char** argv) 
{   
	glutInit(&argc,argv);
	glutInitWindowPosition(100, 100);
	glutInitWindowSize(640, 480);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
	glutCreateWindow("OpenGL");
	glMatrixMode(GL_PROJECTION);
	gluOrtho2D(-240, 240, -180, 180);
	glutDisplayFunc(display);
	glutMainLoop();
	return 0; 
}