/*
 * simple.java
 * This is a simple, introductory OpenGL program.
 */

import jgl.GL;
import jgl.GLApplet;

public class simple extends GLApplet {

    public void display () {
	/* clear all pixels */
	myGL.glClear (GL.GL_COLOR_BUFFER_BIT);

	/*
	 * draw white polygon (rectangle) with corners at
	 * (0.25, 0.25, 0.0) and (0.75, 0.75, 0.0)  
	 */
	myGL.glColor3f (1.0f, 1.0f, 1.0f);
	myGL.glBegin (GL.GL_POLYGON);
	    myGL.glVertex3f (0.25f, 0.25f, 0.0f);
	    myGL.glVertex3f (0.75f, 0.25f, 0.0f);
	    myGL.glVertex3f (0.75f, 0.75f, 0.0f);
	    myGL.glVertex3f (0.25f, 0.75f, 0.0f);
	myGL.glEnd ();

	/*
	 * don't wait!  
	 * start processing buffered OpenGL routines 
	 */
	myGL.glFlush ();
    }

    private void myinit () {
	/* select clearing color */
	myGL.glClearColor (0.0f, 0.0f, 0.0f, 0.0f);

	/* initialize viewing values */
	myGL.glMatrixMode (GL.GL_PROJECTION);
	myGL.glLoadIdentity ();
	myGL.glOrtho (0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f);
    }

    /* 
     * 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.
     */
    public void init () {
	myUT.glutInitWindowSize (500, 500);
	myUT.glutInitWindowPosition (0, 0);
	myUT.glutCreateWindow (this);
	myinit ();
	myUT.glutDisplayFunc ("display");
	myUT.glutMainLoop ();
    }

}