Java实现Vicsek分形绘制异常问题咨询

问题根因 #

• 迭代公式权重错误：Vicsek分形混沌游戏的正确迭代规则是新坐标 = (2*顶点坐标 + 当前点坐标)/3，你原先写的(firstDotx + 顶点x)/3权重完全颠倒，顶点仅占1/3权重，导致生成的图案不断缩小、偏移到角落；而你尝试的firstDotx*3/2计算逻辑会让坐标快速超出绘制区域，自然完全无显示。
• 成员变量状态残留：你将当前点坐标firstDotx、firstDoty设为类成员变量，第一次绘制完成后坐标已经缩到异常范围，后续重绘会直接在错误位置迭代，无法生成图案。
• 点绘制兼容问题：使用drawRect(x,y,0,0)在部分Swing渲染配置下不会显示1像素点，容易出现无绘制内容的问题。
• case4注释笔误：case4对应右上角顶点，注释写为bottom left属于笔误，不影响代码运行。

修复后代码 #

SquarePanel.java #

package fractals;

import java.awt.Color;
import javax.swing.JPanel;
import java.awt.Graphics;
import java.awt.Graphics2D;

public class SquarePanel extends JPanel {
    static final int[] xPoints = new int[]{270, 270, 810, 810};//正方形x坐标
    static final int[] yPoints = new int[]{92, 632, 632, 92};//正方形y坐标
    public final static int iterations = 100000;

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        // 每次绘制都重新初始化随机初始点，避免状态残留
        int firstDotx = 270 + (int) (Math.random() * ((810 - 270) + 1)); 
        int firstDoty = 92 + (int) (Math.random() * ((632 - 92) + 1));
        
        Graphics2D g2 = (Graphics2D) g;
        g2.setColor(Color.black);
        g2.drawPolygon(xPoints, yPoints, 4);
        g2.fillRect(firstDotx, firstDoty, 1, 1);
        
        for (int i = 0; i <= iterations; i++) {
            int midpointX;
            int midpointY;
            int Vertex = (int) (Math.random() * 5 + 1);
            switch (Vertex) { 
                case 1: //左上角
                    g2.setColor(Color.blue);
                    midpointX = (firstDotx + 2*270) / 3;
                    midpointY = (firstDoty + 2*92) / 3;
                    g2.fillRect(midpointX, midpointY, 1, 1);
                    firstDotx = midpointX;
                    firstDoty = midpointY;
                    break;
                case 2://左下角
                    g2.setColor(Color.blue);
                    midpointX = (firstDotx + 2*270) / 3;
                    midpointY = (firstDoty + 2*632) / 3;
                    g2.fillRect(midpointX, midpointY, 1, 1);
                    firstDotx = midpointX;
                    firstDoty = midpointY;
                    break;
                case 3://右下角
                    g2.setColor(Color.blue);
                    midpointX = (firstDotx + 2*810) / 3;
                    midpointY = (firstDoty + 2*632) / 3;
                    g2.fillRect(midpointX, midpointY, 1, 1);
                    firstDotx = midpointX;
                    firstDoty = midpointY;
                    break;
                case 4://右上角
                    g2.setColor(Color.blue);
                    midpointX = (firstDotx + 2*810) / 3;
                    midpointY = (firstDoty + 2*92) / 3;
                    g2.fillRect(midpointX, midpointY, 1, 1);
                    firstDotx = midpointX;
                    firstDoty = midpointY;
                    break;
                case 5://中心
                    g2.setColor(Color.red);
                    midpointX = (firstDotx + 2*540) / 3;
                    midpointY = (firstDoty + 2*384) / 3;
                    g2.fillRect(midpointX, midpointY, 1, 1);
                    firstDotx = midpointX;
                    firstDoty = midpointY;
                    break;
                default:
                    break;
            }
        }
    }
}

SqaureFrame.java（和原代码一致，无修改） #

package fractals;

import javax.swing.JButton;
import javax.swing.JFrame;
import static javax.swing.JFrame.EXIT_ON_CLOSE;

public class SqaureFrame {
    public static void main(String[] args) {
        JFrame Sframe = new JFrame("Vicsek Fractal");
        Sframe.setSize(1080, 768);
        Sframe.setLocation(300, 200);
        Sframe.setDefaultCloseOperation(EXIT_ON_CLOSE);
        SquarePanel Vicsek = new SquarePanel();
        JButton Square = new JButton("Click for the Vicsek Fractal");
        Sframe.add(Vicsek);
        Sframe.setVisible(true);
    }
}

修复后运行即可在指定正方形区域生成完整的Vicsek分形，四个角落区域为蓝色，中心区域为红色。

内容的提问来源于stack exchange，提问作者Joshycookie