/*
 *  texture3d.java
 *  This program demonstrates using a three-dimensional texture.
 *  It creates a 3D texture and then renders two rectangles
 *  with different texture coordinates to obtain different
 *  "slices" of the 3D texture.
 */

import jgl.GL;
import jgl.GLApplet;

public class texture3d extends GLApplet {

    private static final int iWidth = 16;
    private static final int iHeight = 16;
    private static final int iDepth = 16;

    private byte image [][][][] =
    		   new byte [iDepth][iHeight][iWidth][3];
    private int texName [] = new int [1];

    /*  Create a 16x16x16x3 array with different color values in
     *  each array element [r, g, b].  Values range from 0 to 255.
     */
    private void makeImage () {
    	int s, t, r;

	for (s = 0; s < 16; s++) {
	    for (t = 0; t < 16; t++) {
		for (r = 0; r < 16; r++) {
		    image [r][s][t][0] = (byte)(s * 17);
		    image [r][s][t][1] = (byte)(t * 17);
		    image [r][s][t][2] = (byte)(r * 17);
		}
	    }
	}
    }

    /*  Initialize state: the 3D texture object and its image.
     */
    private void myinit () {
	myGL.glClearColor (0.0f, 0.0f, 0.0f, 0.0f);
	myGL.glShadeModel (GL.GL_FLAT);
	myGL.glEnable (GL.GL_DEPTH_TEST);

	makeImage ();
	myGL.glPixelStorei (GL.GL_UNPACK_ALIGNMENT, 1);

	myGL.glGenTextures (1, texName);
	myGL.glBindTexture (GL.GL_TEXTURE_3D, texName [0]);

	myGL.glTexParameterf (GL.GL_TEXTURE_3D, GL.GL_TEXTURE_WRAP_S, GL.GL_CLAMP);
	myGL.glTexParameterf (GL.GL_TEXTURE_3D, GL.GL_TEXTURE_WRAP_T, GL.GL_CLAMP);
	myGL.glTexParameterf (GL.GL_TEXTURE_3D, GL.GL_TEXTURE_WRAP_R, GL.GL_CLAMP);

	myGL.glTexParameterf (GL.GL_TEXTURE_3D, GL.GL_TEXTURE_MAG_FILTER, GL.GL_NEAREST);
	myGL.glTexParameterf (GL.GL_TEXTURE_3D, GL.GL_TEXTURE_MIN_FILTER, GL.GL_NEAREST);
	myGL.glTexImage3D (GL.GL_TEXTURE_3D, 0, GL.GL_RGB, iWidth, iHeight,
	    iDepth, 0, GL.GL_RGB, GL.GL_UNSIGNED_BYTE, image);
	myGL.glEnable (GL.GL_TEXTURE_3D);
    }

    public void display () {
	myGL.glClear (GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT);
	myGL.glBegin (GL.GL_QUADS);
	myGL.glTexCoord3f (0.0f, 0.0f, 0.0f); myGL.glVertex3f (-2.25f, -1.0f, 0.0f);
	myGL.glTexCoord3f (0.0f, 1.0f, 0.0f); myGL.glVertex3f (-2.25f, 1.0f, 0.0f);
	myGL.glTexCoord3f (1.0f, 1.0f, 1.0f); myGL.glVertex3f (-0.25f, 1.0f, 0.0f);
	myGL.glTexCoord3f (1.0f, 0.0f, 1.0f); myGL.glVertex3f (-0.25f, -1.0f, 0.0f);

	myGL.glTexCoord3f (0.0f, 0.0f, 1.0f); myGL.glVertex3f (0.25f, -1.0f, 0.0f);
	myGL.glTexCoord3f (0.0f, 1.0f, 1.0f); myGL.glVertex3f (0.25f, 1.0f, 0.0f);
	myGL.glTexCoord3f (1.0f, 1.0f, 0.0f); myGL.glVertex3f (2.25f, 1.0f, 0.0f);
	myGL.glTexCoord3f (1.0f, 0.0f, 0.0f); myGL.glVertex3f (2.25f, -1.0f, 0.0f);
	myGL.glEnd ();
	myGL.glFlush ();
    }

    public void myReshape (int w, int h) {
        myGL.glViewport (0, 0, w, h);
        myGL.glMatrixMode (GL.GL_PROJECTION);
        myGL.glLoadIdentity ();
	myGLU.gluPerspective (60.0, 1.0 * (double)w/(double)h, 1.0, 30.0);
        myGL.glMatrixMode (GL.GL_MODELVIEW);
        myGL.glLoadIdentity ();
	myGL.glTranslatef (0.0f, 0.0f, -4.0f);
    }

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

}