#include <GL/glut.h>

void mydisplay(){
	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(); 
}

int main(int argc, char** argv){
	glutCreateWindow("simple");     
	glutDisplayFunc(mydisplay);    
	glutMainLoop();
}