import java.applet.Applet;
import java.awt.Graphics;
import java.awt.event.ComponentEvent;
import java.awt.event.ComponentListener;
import java.awt.event.InputEvent;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.lang.System;

// must import jgl.GL....
import jgl.GL;
import jgl.GLU;
import jgl.GLAUX;

public class picksquare extends Applet
			implements ComponentListener, MouseListener {
    // must use GL to use jGL.....
    // and use GLU to use the glu functions....
    // remember to give GL to initialize GLU
    // and use GLAUX to use the aux functions.....
    // remember to give GL to initialize GLAUX
    GL myGL = new GL ();
    GLU myGLU = new GLU (myGL);
    GLAUX myAUX = new GLAUX (myGL);

    private int board[][] = new int[3][3]; /* amount of color for each square */

    private void myinit () {
	int i, j;
	for (i = 0; i < 3; i++) {
	    for (j = 0; j < 3; j++) {
		board [i][j] = 0;
	    }
	}
	myGL.glClearColor (0.0f, 0.0f, 0.0f, 0.0f); 
    }

    private void drawSquares (int mode) {
	int i, j;
	for (i = 0; i < 3; i++) {
	    if (mode == GL.GL_SELECT) {
		myGL.glLoadName (i);
	    }
	    for (j = 0; j < 3; j ++) {
		if (mode == GL.GL_SELECT) {
		    myGL.glPushName (j);
		}
		myGL.glColor3f ((float)(i/3.0),(float)(j/3.0),(float)(board[i][j]/3.0));
		myGL.glRecti (i, j, i+1, j+1);
		if (mode == GL.GL_SELECT) {
		    myGL.glPopName ();
		}
	    }
	}
    }

    private void processHits (int hits, int buffer []) {
	int i, j;
	int ii = 0, jj = 0, names, ptr;

	System.out.println ("hits = " + hits);
	ptr = 0;
	for (i = 0; i < hits; i++) {        /*  for each hit  */
	    names = buffer [ptr];
	    System.out.println (" number of names for hit = " + names); ptr++;
	    System.out.print ("  z1 is " + buffer [ptr] + ";"); ptr++;
	    System.out.println (" z2 is " + buffer [ptr]); ptr++;
	    System.out.print ("   the name is ");
	    for (j = 0; j < names; j++) {   /*  for each name */
		System.out.print (buffer [ptr] + " ");
		if (j == 0) { /*  set row and column */
		    ii = buffer [ptr];
		} else {
		    jj = buffer [ptr];
		}
		ptr++;
	    }
	    System.out.println ();
	    board [ii][jj] = (board [ii][jj] + 1) % 3;
	}
    }

    private static final int BUFSIZE = 512;

    private void pickSquares (MouseEvent e) {
	int selectBuf [] = new int [BUFSIZE];
	int hits;
	int viewport [] = new int [4];
	int x, y;

	x = e.getX ();
	y = e.getY ();
	myGL.glGetIntegerv (GL.GL_VIEWPORT, viewport);

	myGL.glSelectBuffer (BUFSIZE, selectBuf);
	myGL.glRenderMode (GL.GL_SELECT);

	myGL.glInitNames ();
	myGL.glPushName (-1);

	myGL.glMatrixMode (GL.GL_PROJECTION);
	myGL.glPushMatrix ();
	myGL.glLoadIdentity ();
	/*  create 5x5 pixel picking region near cursor location        */
	myGLU.gluPickMatrix((double)x,(double)(viewport[3]-y),5.0,5.0,viewport);
	myGLU.gluOrtho2D (0.0, 3.0, 0.0, 3.0);
	drawSquares (GL.GL_SELECT);
	myGL.glPopMatrix ();
	myGL.glFlush ();

	hits = myGL.glRenderMode (GL.GL_RENDER);
	processHits (hits, selectBuf);
    }

    public void mouseClicked(MouseEvent e) {}
    public void mouseEntered(MouseEvent e) {}
    public void mouseExited(MouseEvent e) {}
    public void mouseReleased(MouseEvent e) {}

    public void mousePressed(MouseEvent e) {
        // process which button by myself
        if ((e.getModifiers() & InputEvent.BUTTON1_MASK)
            == InputEvent.BUTTON1_MASK) { // left
            pickSquares (e);
            display ();
            repaint ();
            e.consume ();
        }
    } 

    private void display () {
	myGL.glClear (GL.GL_COLOR_BUFFER_BIT);
	drawSquares (GL.GL_RENDER);
	myGL.glFlush ();
    }

    public void componentMoved (ComponentEvent e) {}
    public void componentShown (ComponentEvent e) {}
    public void componentHidden (ComponentEvent e) {}

    public void componentResized (ComponentEvent e) {
        // get window width and height by myself
	myReshape (getSize ().width, getSize ().height);
        display ();
        repaint ();
    }

    private void myReshape (int w, int h) {
        myGL.glViewport (0, 0, w, h);
        myGL.glMatrixMode (GL.GL_PROJECTION);
        myGL.glLoadIdentity ();
        myGLU.gluOrtho2D (0.0, 3.0, 0.0, 3.0);
        myGL.glMatrixMode (GL.GL_MODELVIEW);
        myGL.glLoadIdentity ();
    }

    public void update (Graphics g) {
        // skip the clear screen command....
        paint (g);
    }

    public void paint (Graphics g) {
	myGL.glXSwapBuffers (g, this);
    }

    public void init () {
	myAUX.auxInitPosition (0, 0, 100, 100);
	myAUX.auxInitWindow (this);
	myinit ();

	// as call auxMouseFunc()
        addMouseListener(this);

        // as call auxReshapeFunc()
        addComponentListener (this);
	myReshape (getSize ().width, getSize ().height);

        // call display as call auxIdleFunc(display)
        display ();
    }

}