// Mandelbrot.java  (Ver.1.00)
// Mandelbrot Fractal Drawing class
// Copyright (C) 1997 Y.Nagatani
// nagatani@eken.phys.nagoya-u.ac.jp

import java.awt.*;

public class Mandelbrot {
	
	public	double	realStart = -2.1,	realWidth = 3.0,
			imagStart = -1.5,	imagWidth = 3.0;
	public	int	xMax    = 200,		yMax   = 200;
	public	boolean	bAbsolute = true;
	public	int	nNestLevel = 64;
	public	boolean	bLowResolution = true;;
	
	Mandelbrot (int xMax, int yMax) {
		
		this.xMax = xMax;
		this.yMax = yMax;
	}
	public Mandelbrot setRegion (double realStart, double imagStart,
				     double realWidth, double imagWidth) {
		
		this.realStart = realStart;
		this.imagStart = imagStart;
		this.realWidth = realWidth;
		this.imagWidth = imagWidth;
		return	this;
	}
	public Mandelbrot setNestLevel (int nNestLevel) {
		
		this.nNestLevel = nNestLevel;
		return	this;
	}
	public Mandelbrot setAbsoluteMode () {
		
		this.bAbsolute  = true;
		return	this;
	}
	public Mandelbrot setPhaseMode () {
		
		this.bAbsolute  = false;
		return	this;
	}
	public Mandelbrot setLowResolution () {
		
		this.bLowResolution  = true;
		return	this;
	}
	public Mandelbrot setHighResolution () {
		
		this.bLowResolution  = false;
		return	this;
	}
		
	private double GetFracAbsolute (double r0, double i0) {
		
		int	n;
		double	r,	i,	r1;
		r  = r0;			/* Z(0) = c		*/
		i  = i0;
		for (n = nNestLevel ; n > 0 ; n--) {
			r1 = r0 + r*r - i*i;	/* Z(n+1) = c + z(n)^2	*/
			i  = i0 + 2.0*r*i;
			r  = r1;
			if (r*r + i*i > 4.0)	/* continue if |Z| < 4	*/
				break;
		}
		return	1.0 * n / nNestLevel;
	}
	
	private double GetFracPhase (double r0, double i0)
	{
		double	r,	i,	r1;
		r  = 0;
		i  = 0;
		for (int n = 0 ; n < nNestLevel ; n++) {
			r1 = r0 + r*r - i*i;
			i  = i0 + 2.0*r*i;
			r  = r1;
		}
		
		double	arg;
		if (Math.abs(i) < 0.0000000000001)
			arg = (r > 0 ? 0 : Math.PI);
		else
			arg = Math.atan2 (i, r);
		
		return	arg / 2.0 / Math.PI;
	}
	
	public void Put1Line (int y, Graphics g)
	{
		double	i = imagStart + imagWidth * (yMax - y) / yMax;
		for (int x = 0 ; x < xMax ; x++) {
			double	r = realStart + realWidth * x / xMax;
			
			double	f;
			if (bAbsolute)
				f = GetFracAbsolute (r, i) * 0.8;
			else
				f = GetFracPhase (r, i);
			
			g.setColor (new Color (Color.HSBtoRGB (
				(float)f, (float)1.0, (float)1.0)));
			g.drawLine (x, y, x+1, y);
			if (bLowResolution) {
				g.drawLine (x, y+1, x+1, y+1);
				x++;
			}
		}
	}
	
	int	y = 0;
	public void SubPaintInit () {
		y = 0;
	}
	
	public boolean SubPaint (Graphics g)
	{
		for (int n = 0 ; n < 5 ; n++) {
			Put1Line (y++, g);
			if (y >= yMax) {
				y = 0;
				return	false;	// completed
			}
			if (bLowResolution)
				y++;
		}
		return	true;	// uncompleted
	}
	
	public void paint (Graphics g)
	{
		this.SubPaintInit ();
		while (SubPaint (g));
	}
}