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 pickdepth 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 void myinit () {
	myGL.glClearColor (0.0f, 0.0f, 0.0f, 0.0f); 
	myGL.glDepthFunc (GL.GL_LEQUAL);
	myGL.glEnable (GL.GL_DEPTH_TEST);
	myGL.glShadeModel (GL.GL_FLAT);
	myGL.glDepthRange (0.0f, 1.0f); /* The default z mapping */
    }

    private void drawRects (int mode) {
	if (mode == GL.GL_SELECT) { 
	    myGL.glLoadName (1);
	}
	myGL.glBegin (GL.GL_QUADS);
	    myGL.glColor3f (1.0f, 1.0f, 0.0f);
	    myGL.glVertex3i (2, 0, 0);
	    myGL.glVertex3i (2, 6, 0);
	    myGL.glVertex3i (6, 6, 0);
	    myGL.glVertex3i (6, 0, 0);
	    myGL.glColor3f (0.0f, 1.0f, 1.0f);
	    myGL.glVertex3i (3, 2, -1);
	    myGL.glVertex3i (3, 8, -1);
	    myGL.glVertex3i (8, 8, -1);
	    myGL.glVertex3i (8, 2, -1);
	    myGL.glColor3f (1.0f, 0.0f, 1.0f);
	    myGL.glVertex3i (0, 2, -2);
	    myGL.glVertex3i (0, 7, -2);
	    myGL.glVertex3i (5, 7, -2);
	    myGL.glVertex3i (5, 2, -2);
	myGL.glEnd ();
    }

    private void processHits (int hits, int buffer []) {
	int i, j;
	int 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] + " "); ptr++;
	    }
	    System.out.println ();
	}
    }

    private static final int BUFSIZE = 512;

    private void pickRects (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);
	myGL.glOrtho (0.0f, 8.0f, 0.0f, 8.0f, -0.5f, 2.5f);
	drawRects (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
            pickRects (e);
            display ();
            repaint ();
            e.consume ();
        }
    }

    private void display () {
	myGL.glClear (GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT);
	drawRects (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 ();
	myGL.glOrtho (0.0f, 8.0f, 0.0f, 8.0f, -0.5f, 2.5f);
        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 ();
    }

}