/*
 * picksquare.java
 * Use of multiple names and picking are demonstrated.  
 * A 3x3 grid of squares is drawn.  When the left mouse 
 * button is pressed, all squares under the cursor position 
 * have their color changed.
 */

import java.awt.Frame;
import java.io.IOException;
import java.lang.String;
import java.lang.System;

import jgl.GL;
import jgl.GLUT;
import jgl.GLCanvas;

public class picksquare extends GLCanvas {

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

    /* Clear color value for every square on the board */
    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); 
    }

    /*
     *  The nine squares are drawn.  In selection mode, each 
     *  square is given two names:  one for the row and the 
     *  other for the column on the grid.  The color of each 
     *  square is determined by its position on the grid, and 
     *  the value in the board[][] array.
     */
    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 ();
	    }
	}
    }

    /*
     *  processHits prints out the contents of the 
     *  selection array.
     */
    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;
	}
    }

    /*
     *  pickSquares() sets up selection mode, name stack, 
     *  and projection matrix for picking.  Then the 
     *  objects are drawn.
     */
    private static final int BUFSIZE = 512;

    public void pickSquares (int button, int state, int x, int y) {
	int selectBuf [] = new int [BUFSIZE];
	int hits;
	int viewport [] = new int [4];

	if (button != GLUT.GLUT_LEFT_BUTTON || state != GLUT.GLUT_DOWN)
	    return;

	myGL.glGetIntegerv (GL.GL_VIEWPORT, viewport);

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

	myGL.glInitNames ();
	myGL.glPushName (0);

	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.glMatrixMode (GL.GL_PROJECTION);
	myGL.glPopMatrix ();
	myGL.glFlush ();

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

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

    public 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 ();
    }

    /* ARGSUSED1 */
    public void keyboard (char key, int x, int y) {
	switch (key) {
	    case 27:
		System.exit(0);
	    default:
		break;
	}
    }

    /* Main Loop */
    public void init () {
	myUT.glutInitWindowSize (100, 100);
	myUT.glutInitWindowPosition (0, 0);
	myUT.glutCreateWindow (this);
	myinit ();
	myUT.glutReshapeFunc ("myReshape");
	myUT.glutDisplayFunc ("display");
	myUT.glutMouseFunc ("pickSquares");
	myUT.glutKeyboardFunc ("keyboard");
	myUT.glutMainLoop ();
    }

    static public void main (String args[]) throws IOException {
	Frame mainFrame = new Frame ();
	mainFrame.setSize (108, 127);
	picksquare mainCanvas = new picksquare ();
	mainCanvas.init();
	mainFrame.add (mainCanvas);
	mainFrame.setVisible (true);
    }

}