きったんの頭_ん中☆

// <applet code="Mondelbrot.class" width="600" height="400"></applet>

/**
 * Mondelbrot.java
 * @see https://mind.kittttttan.info/java/mandelbrot.html
 */

import java.applet.* ;
import java.awt.* ;

public class Mondelbrot extends Applet {
    private static int LOOP = 255;
    private static int ZOOM = 200;
    private static int WIDTH = ZOOM*3;
    private static int HEIGHT = ZOOM*2;

    public static int lim(double x, double y) {
        int c = 0;
        double nx, ny, px = 0, py = 0;
        for (int i = 0; i < LOOP; i++) {
            nx = px*px - py*py + x;
            ny = 2*px*py + y;
            if (nx*nx + ny*ny > 4.0) {
                c = i+1;
                break;
            }
            px = nx;
            py = ny;
        }
        if (c == 0) {c = LOOP;}
        return c;
    }

    public void paint(Graphics g) {
        int t;
        for (int i = 0; i < WIDTH; i++) {
            for (int j = 0; j < HEIGHT; j++) {
                t = lim((double)i/ZOOM - 2.0, (double)j/ZOOM - 1.0);
                if (t < LOOP) {
                    t <<= 4;
                    if (t > 255) {t = 255;}
                    g.setColor(new Color(0, 0, t));
                } else {
                    g.setColor(Color.black);
                }
                g.fillRect(i, j, 1, 1);
            }
        }
    }
}