#include <glut.h>         /* glut.h includes gl.h and glu.h*/

void display(void)
{
	 glClear(GL_COLOR_BUFFER_BIT); 
	glBegin(GL_POLYGON);
	 	glVertex2f(-0.5, -0.5);
	 	glVertex2f(0.5, 0.5);
	 	glVertex2f(-0.5, 0.5);
	 	glVertex2f(0.5, -0.5);
	glEnd();
	glFlush(); 
}

void init()
{
	glClearColor (0.0, 0.0, 0.0, 0.0); 
 	glColor3f(1.0, 1.0, 1.0); 
	glMatrixMode (GL_PROJECTION);
	glLoadIdentity ();
	glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0); 
}

int main(int argc, char** argv)
{
 	glutInit(&argc,argv); 
	glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);  
	glutInitWindowSize(500,500);
	glutInitWindowPosition(0,0); 
	glutCreateWindow("simple"); 
	glutDisplayFunc(display);
	init();
	glutMainLoop();
}