今天來寫k階科赫雪花的遞歸實現，(K值需要你手動輸入)至于科赫雪花是什么請大家自行百度。
首先來思考這個程序怎么寫，當 count = 0 時就應該是一個三角形，這三個點是你一開始就確定的，以后的改變都依據這三個點發展的。當不是0的時候就需要計算相對于這個三角形的9個點，分別是每條邊上的兩個點，和它對應的三角形第三個頂點。
首先在JFrame中添加一個panel，我們需要在這個panel上畫圖。
大家再來看這個圖片，這張圖介紹了通過兩個點來計算其他三個點的過程。
現在開始在panel中畫圖：
static class showpanel extends JPanel{
int number = 0;
public void setNumber(int number) {
this.number = number;
repaint();
}
public void paintComponent(Graphics g) {
super.paintComponent(g);//畫一個簡單的panel
int side =(int)(Math.min((int)getWidth(),(int)getHeight())*0.8);
int high =(int)(side*Math.cos(Math.toRadians(30)));
Point p1 = new Point(getWidth() / 2, 10);
Point p2 = new Point(getWidth() / 2 - side / 2, 10 + high);
Point p3 = new Point(getWidth() / 2 + side / 2, 10 + high);
playKochSnowFlake(g, number, p1, p2);
playKochSnowFlake(g, number, p2, p3);
playKochSnowFlake(g, number, p3, p1);
}
現在開始寫遞歸函數。
public static void playKochSnowFlake(Graphics g,int number,Point p1,Point p2) {
if(number == 0){
g.drawLine(p1.x, p1.y,p2.x, p2.y);
}
else{
int deltaX = p2.x - p1.x;
int deltaY = p2.y - p1.y;
Point x = new Point(p1.x + deltaX / 3, p1.y + deltaY / 3);
Point y = new Point(p1.x + deltaX * 2 / 3, p1.y + deltaY * 2 / 3);
Point z = new Point(
(int)((p1.x + p2.x) / 2 + Math.sin(Math.toRadians(60)) * (p1.y - p2.y) / 3),
(int)((p1.y + p2.y) / 2 + Math.sin(Math.toRadians(60)) * (p2.x - p1.x) / 3));
playKochSnowFlake(g, number - 1, p1, x);
playKochSnowFlake(g, number - 1, x, z);
playKochSnowFlake(g, number - 1, z, y);
playKochSnowFlake(g, number - 1, y, p2);
}
}
然后在主面板中加入一個JTextField jta 它輸入的數據要傳入到number中。所以為其添加一個監聽器。 已有數據輸入就調用其中的setNumber()函數設置number變量。
jta.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
spl.setNumber(Integer.parseInt(jta.getText()));
}
});
所以總體已經完成了，剩下的就是簡答的窗體設置。
下面貼一個完整的java代碼：
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class SnowFlake extends JFrame {
private JTextField jta = new JTextField(5);
private showpanel spl = new showpanel();
static class showpanel extends JPanel{
int number = 0;
public void setNumber(int number) {
this.number = number;
repaint();
}
public void paintComponent(Graphics g) {
super.paintComponent(g);//畫一個簡單的panel
int side =(int)(Math.min((int)getWidth(),(int)getHeight())*0.8);
int high =(int)(side*Math.cos(Math.toRadians(30)));
Point p1 = new Point(getWidth() / 2, 10);
Point p2 = new Point(getWidth() / 2 - side / 2, 10 + high);
Point p3 = new Point(getWidth() / 2 + side / 2, 10 + high);
playKochSnowFlake(g, number, p1, p2);
playKochSnowFlake(g, number, p2, p3);
playKochSnowFlake(g, number, p3, p1);
}
public static void playKochSnowFlake(Graphics g,int number,Point p1,Point p2) {
if(number == 0){
g.drawLine(p1.x, p1.y,p2.x, p2.y);
}
else{
int deltaX = p2.x - p1.x;
int deltaY = p2.y - p1.y;
Point x = new Point(p1.x + deltaX / 3, p1.y + deltaY / 3);
Point y = new Point(p1.x + deltaX * 2 / 3, p1.y + deltaY * 2 / 3);
Point z = new Point(
(int)((p1.x + p2.x) / 2 + Math.sin(Math.toRadians(60)) * (p1.y - p2.y) / 3),
(int)((p1.y + p2.y) / 2 + Math.sin(Math.toRadians(60)) * (p2.x - p1.x) / 3));
playKochSnowFlake(g, number - 1, p1, x);
playKochSnowFlake(g, number - 1, x, z);
playKochSnowFlake(g, number - 1, z, y);
playKochSnowFlake(g, number - 1, y, p2);
}
}
}
public SnowFlake() {
JPanel panel = new JPanel();
panel.setLayout(new FlowLayout());
panel.add(new JLabel("Please input the number"));
panel.add(jta);
add(spl,BorderLayout.CENTER);
add(panel,BorderLayout.SOUTH);
jta.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
spl.setNumber(Integer.parseInt(jta.getText()));
}
});
}
public static void main(String args[]) {
SnowFlake snowFlake = new SnowFlake();
snowFlake.setSize(300, 300);
snowFlake.setTitle("SnowFlake");
snowFlake.setLocationRelativeTo(null);
snowFlake.setVisible(true);
}
}
效果圖：
以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持億速云。
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