/*
 *  doublebuffer.java
 *  This is a simple double buffered program.
 *  Pressing the left mouse button rotates the rectangle.
 *  Pressing the middle mouse button stops the rotation.
 */

import jgl.GL;
import jgl.GLUT;
import jgl.GLApplet;

// "double" is a reserved word in Java
public class doublebuffer extends GLApplet {

    private float spin = 0;

    public void display () {
	myGL.glClear (GL.GL_COLOR_BUFFER_BIT);
	myGL.glPushMatrix ();
	myGL.glRotatef (spin, 0.0f, 0.0f, 1.0f);
	myGL.glColor3f (1.0f, 1.0f, 1.0f);
	myGL.glRectf (-25.0f, -25.0f, 25.0f, 25.0f);
	myGL.glPopMatrix ();

	myGL.glFlush ();
    }

    public void spinDisplay () {
    	spin += 2.0f;
	if (spin > 360.0f) 
	    spin = spin - 360.0f;
	myUT.glutPostRedisplay ();
    }

    private void myinit () {
	myGL.glClearColor (0.0f, 0.0f, 0.0f, 0.0f);
	myGL.glShadeModel (GL.GL_FLAT);
    }

    public void myReshape (int w, int h) {
    	myGL.glViewport (0, 0, w, h);
	myGL.glMatrixMode (GL.GL_PROJECTION);
	myGL.glLoadIdentity ();
	myGL.glOrtho (-50.0f, 50.0f, -50.0f, 50.0f, -1.0f,  1.0f);
	myGL.glMatrixMode (GL.GL_MODELVIEW);
	myGL.glLoadIdentity ();
    }

    /* ARGSUSED2 */
    public void mouse (int button, int state, int x, int y) {
	if (button == GLUT.GLUT_LEFT_BUTTON) {
	    if (state == GLUT.GLUT_DOWN) {
		myUT.glutIdleFunc ("spinDisplay");
	    }
	} else if (button == GLUT.GLUT_MIDDLE_BUTTON) {
	    if (state == GLUT.GLUT_DOWN) {
		myUT.glutIdleFunc (null);
	    }
	}
    }

    /* 
     *  Request double buffer display mode.
     *  Register mouse input callback functions
     */
    public void init () {
	myUT.glutInitWindowSize (500, 500);
	myUT.glutInitWindowPosition (0, 0);
	myUT.glutCreateWindow (this);
	myinit ();
	myUT.glutDisplayFunc ("display");
	myUT.glutReshapeFunc ("myReshape");
	myUT.glutMouseFunc ("mouse");
	myUT.glutMainLoop ();
    }

}