#include <GL/glut.h>
#include <GL/freeglut.h>
#include <GL/gl.h>



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(100, 100);
    glutCreateWindow("hello");
    init();
    glutDisplayFunc(display);
    glutMainLoop();
    return 0; /* ISO C requires main to return int. */
}