/*
 * @(#)Balls.java	1.10 98/06/29
 *
 * Copyright 1998 by Sun Microsystems, Inc.,
 * 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
 * All rights reserved.
 *
 * This software is the confidential and proprietary information
 * of Sun Microsystems, Inc. ("Confidential Information").  You
 * shall not disclose such Confidential Information and shall use
 * it only in accordance with the terms of the license agreement
 * you entered into with Sun.
 */

package demos.Mix;

import java.awt.*;
import java.awt.image.*;
import java.awt.event.*;
import J2DCanvas;


/**
 * Three animated color balls bouncing.
 */
public class Balls extends J2DCanvas {

    private Ball balls[];
    private Color colors[] = { Color.red, Color.green.darker(), Color.blue };
    private long lasttime;
    private int clearNum = 1;
    private boolean active;


    public Balls() {
	setBackground(Color.white);
	balls = new Ball[colors.length];
	runnable = true;
    }


    public void drawDemo(Graphics2D g2) {

	if (newBufferedImage) {
	    for (int i = 0; i < colors.length; i++)
	        balls[i] = new Ball(colors[i], w, h);
	    lasttime = System.currentTimeMillis();
	    clearCanvas = true;
	}

	long now = System.currentTimeMillis();
	long deltaT = now - lasttime;
	active = false;
	for (int i = 0; i < balls.length; i++) {
	    balls[i].step(deltaT);
	    if (balls[i].Vy > .02 || -balls[i].Vy > .02 ||
		    balls[i].y + balls[i].bwidth < h) {
	 	active = true;
 	    }
	}
	if (!active) {
	    for (int i = 0; i < balls.length; i++) {
	        balls[i].Vx = (float)Math.random() / 4.0f - 0.125f;
	        balls[i].Vy = -(float)Math.random() / 4.0f - 0.2f;
	    }
	    clearCanvas = clearNum++%2 == 0;
	    if (clearNum > 100) clearNum = 1;
	}

	for (int i = 0; i < balls.length; i++) {
	    Ball b = balls[i];
	    if (b == null)
		continue;
	    if (b.imgs[b.index] == null)
		continue;
            g2.drawImage(b.imgs[b.index], (int) b.x, (int) b.y, this);
	}
	lasttime = now;
    }


    public static void main(String s[]) {
	final Balls demo = new Balls();
	WindowListener l = new WindowAdapter() {
	    public void windowClosing(WindowEvent e) {System.exit(0);}
	    public void windowDeiconified(WindowEvent e) { demo.start(); }
	    public void windowIconified(WindowEvent e) { demo.stop(); }
	};
	Frame f = new Frame("Java2D Demo - Balls");
	f.addWindowListener(l);
	f.add("Center", demo);
	f.pack();
	f.setSize(new Dimension(400,300));
	f.show();
	demo.start();
    }


public class Ball {
    public int bwidth, bheight;
    public float x, y;
    public float Vx = 0.1f;
    public float Vy = 0.05f;
    public int nImgs = 5;
    public BufferedImage imgs[];
    public int index = (int) (Math.random() * (nImgs-1));

    private final float inelasticity = .96f;
    private final float Ax = 0.0f;
    private final float Ay = 0.0002f;
    private final float Ar = 0.9f;
    private final int UP = 0;
    private final int DOWN = 1;
    private int indexDirection = UP;
    private int w, h;


    public Ball(Color color, int w, int h) {
	this.w = w;
	this.h = h;
        int R = w/10;
	x = (float) (Math.random() * w);
	bwidth = R*2;
	bheight = R*2;
	byte[] data = new byte[R * 2 * R * 2];
	int maxr = 0;
	for (int Y = 2 * R; --Y >= 0;) {
	    int x0 = (int) (Math.sqrt(R * R - (Y - R) * (Y - R)) + 0.5);
	    int p = Y * (R * 2) + R - x0;
	    for (int X = -x0; X < x0; X++) {
		int x = X + 15;
		int y = Y - R + 15;
		int r = (int) (Math.sqrt(x * x + y * y) + 0.5);
		if (r > maxr)
		    maxr = r;
		data[p++] = r <= 0 ? 1 : (byte) r;
	    }
	}

	imgs = new BufferedImage[nImgs];

        int bg = 255;
	byte red[] = new byte[256];
	red[0] = (byte) bg;
	byte green[] = new byte[256];
	green[0] = (byte) bg;
	byte blue[] = new byte[256];
	blue[0] = (byte) bg;

	for (int r = 0; r < imgs.length; r++) {
	    float b = 0.5f + (float) ((r+1f)/imgs.length/2f);
	    for (int i = maxr; i >= 1; --i) {
	        float d = (float) i / maxr;
	 	red[i] = (byte) blend(blend(color.getRed(), 255, d), bg, b);
	 	green[i] = (byte) blend(blend(color.getGreen(), 255, d), bg, b);
	 	blue[i] = (byte) blend(blend(color.getBlue(), 255, d), bg, b);
	    }
	    IndexColorModel icm = new IndexColorModel(8, maxr + 1,
			red, green, blue, 0);
            DataBufferByte dbb = new DataBufferByte(data, data.length);
            int bandOffsets[] = {0};
            WritableRaster wr = Raster.createInterleavedRaster(dbb,
	        R*2,R*2,R*2,1, bandOffsets,null);
            imgs[r] = new BufferedImage(icm, wr, icm.isAlphaPremultiplied(),null);
	}
    }


    private final int blend(int fg, int bg, float fgfactor) {
	return (int) (bg + (fg - bg) * fgfactor);
    }


    public void step(long deltaT) {
	boolean	collision_x = false;
	boolean	collision_y = false;

	float jitter = (float)Math.random() * .01f - .005f;

	x += Vx * deltaT + (Ax / 2.0) * deltaT * deltaT;
	y += Vy * deltaT + (Ay / 2.0) * deltaT * deltaT;
	if (x <= 0.0f) {
	    x = 0.0f;
	    Vx = -Vx * inelasticity + jitter;
	    collision_x = true;
	}
	Dimension d = getSize();
	if (x + bwidth >= w) {
	    x = w - bwidth;
	    Vx = -Vx * inelasticity + jitter;
	    collision_x = true;
	}
	if (y <= 0) {
	    y = 0;
	    Vy = -Vy * inelasticity + jitter;
	    collision_y = true;
	}
	if (y + bheight >= h) {
	    y = h - bheight;
	    Vx *= inelasticity;
	    Vy = -Vy * inelasticity + jitter;
	    collision_y = true;
	}
	Vy = Vy + Ay * deltaT;
	Vx = Vx + Ax * deltaT;

        if (indexDirection == UP)
	    index++;
        if (indexDirection == DOWN)
	    --index;
        if (index+1 == nImgs)
            indexDirection = DOWN;
        if (index == 0)
            indexDirection = UP;
    }
}  // End class Ball

}