#include <GL/glut.h>

// g++ -o p main.cpp -lGL -lglut
// ./p

void display(void)
{
    /* clear all pixels */
    glClear(GL_COLOR_BUFFER_BIT);
    /* draw white polygon (rectangle) with corners at
      (0.25, 0.25, 0.0) and (0.75, 0.75, 0.0) */
    glColor3f(1.0, 1.0, 1.0);
    glBegin(GL_POLYGON);
		glVertex3f(0.25, 0.25, 0.0);
		glVertex3f(0.75, 0.25, 0.0);
		glVertex3f(0.75, 0.75, 0.0);
		glVertex3f(0.25, 0.75, 0.0);
    glEnd();
    /* don't wait!
       start processing buffered OpenGL routines */
    glFlush ();
}

void init(void)
{
    /* select clearing (background) color */
    glClearColor(0.0, 0.0, 0.0, 0.0);
    /* initialize viewing values */
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
}
/* Declare initial window size, position, and display mode
   (single buffer and RGBA). Open window with "hello"
   in its title bar. Call initialization routines.
   Register callback function to display graphics.
   Enter main loop and process events. */
int main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(250, 250);
    glutInitWindowPosition(670, 330);
    glutCreateWindow("hello");
    init();
    glutDisplayFunc(display);
    glutMainLoop();
	
    return 0; /* ISO C requires main to return int. */
}