我正在制作一个蛇游戏，而我却陷入了使尾巴跟随头部的地方。我听说在头上使用添加和删除，尾巴可以实现这一点，但我不知道从哪里开始。
到目前为止，这是我的代码：
Screen.java
public class Screen extends JPanel implements ActionListener, KeyListener {
public static final JLabel statusbar = new JLabel("Default");
public static final int WIDTH = 800, HEIGHT = 800;
Timer t = new Timer(100, this);
int x = 400;
int y = 400;
int size = 5; //increase size if eat
private boolean right = false, left = false, up = false, down = false;
int head = 0;
private LinkedList<BodyPart> snake = new LinkedList<BodyPart>();
private BodyPart b;
public Screen(){
initSnake();
t.start();
addKeyListener(this);
setFocusable(true);
setFocusTraversalKeysEnabled(false);
}
public void update(){
}
public void direction(){
if(right) x+=10;
if(left) x-=10;
if(up) y-=10;
if(down) y+=10;
}
public void trackOutBound(){
if(x < 0 || x > 800 || y < 0 || y > 800) {
x = 400;
y = 400;
}
}
public void initSnake(){
if(snake.size() == 0){
b = new BodyPart(x, y);
for(int i = 0; i < size; i++) {
snake.add(b);
}
System.out.println(snake);
}
}
public static void main(String[] args) {
}
@Override
public void paintComponent(Graphics g){
super.paintComponent(g);
g.setColor(new Color(10, 50, 0));
g.fillRect(0, 0, WIDTH, HEIGHT);
g.setColor(Color.BLACK);
for(int i = 0; i < WIDTH / 10; i++) {
g.drawLine(i * 10, 0, i * 10, HEIGHT);
}
for(int i = 0; i < HEIGHT / 10; i++) {
g.drawLine(0, i * 10, WIDTH, i * 10);
}
int tempx = 0, tempy = 0;
int temp = 0;
for(int i = 0; i < size; i++){
if(i == head) {
snake.get(i).x = x;
snake.get(i).y = y;
snake.get(i).draw(g);
g.setColor(Color.blue);
g.fillRect(x, y, 10, 10);
g.setColor(Color.white);
g.drawRect(x, y, 10, 10);
} else if(i > 0 && up) {
snake.get(i).x = x;
snake.get(i).y = y + temp;
snake.get(i).draw(g);
} else if(i > 0 && down) {
snake.get(i).x = x;
snake.get(i).y = y - temp;
snake.get(i).draw(g);
} else if(i > 0 && left) {
snake.get(i).x = x + temp;
snake.get(i).y = y;
snake.get(i).draw(g);
} else if(i > 0 && right) {
snake.get(i).x = x - temp;
snake.get(i).y = y;
snake.get(i).draw(g);
}
temp += 10;
}
/*
if(snake.size() == 5){
snake.add(b);
size += 1;
}
*/
}
@Override
public void actionPerformed(ActionEvent e) {
direction();
trackOutBound();
repaint();
// System.out.println(snake);
statusbar.setText("(" + x + " , " + y + ")");
}
@Override
public void keyTyped(KeyEvent e) {}
@Override
public void keyPressed(KeyEvent e) {
int key = e.getKeyCode();
if(key == KeyEvent.VK_RIGHT && !left) {
up = false;
down = false;
right = true;
}
if(key == KeyEvent.VK_LEFT && !right) {
up = false;
down = false;
left = true;
}
if(key == KeyEvent.VK_UP && !down) {
left = false;
right = false;
up = true;
}
if(key == KeyEvent.VK_DOWN && !up) {
left = false;
right = false;
down = true;
}
}
@Override
public void keyReleased(KeyEvent e) {}
}
BodyPart.java
public class BodyPart {
int x;
int y;
public BodyPart(int x, int y) {
this.x = x;
this.y = y;
}
public void draw(Graphics g) {
this.x = x;
this.y = y;
g.setColor(Color.red);
g.fillRect(x, y, 10, 10);
g.setColor(Color.white);
g.drawRect(x, y, 10, 10);
}
}
Frame.java
public class Frame extends JPanel {
private static JLabel statusbar = new JLabel("Default");
public void statusbar(){
statusbar = Screen.statusbar;
}
public static void main(String[] args) {
JFrame f = new JFrame();
Screen s = new Screen();
f.add(s);
f.add(statusbar, BorderLayout.SOUTH);
f.setSize(800, 800);
f.setVisible(true);
f.setLocationRelativeTo(null);
f.setResizable(false);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
现在这段代码只会使尾部翻转到水平或垂直，是否可以通过使用此代码使尾部跟随头部？或者我需要更改我的代码？
谢谢
答案 0 :(得分：3)
基本的想法是，你需要某种List包含蛇的所有点。从概念上讲，List将包含虚拟坐标，即1x1表示虚拟空间中的坐标，它在虚拟板上呈现一个位置（具有一些宽度和高度）。
然后您可以将其转换为屏幕，因此这将允许蛇的每个部分比单个像素更大。因此，如果每个部分都是5x5像素，那么屏幕上的1x1实际上就是5x5。
每次蛇移动时，都会向头部添加一个新值并从尾部移除最后一个值（假设它没有增长）。当你需要画蛇时，你只需要遍历List，画出蛇的每个点。
以下是一个简单的示例，它使用LinkedList，将新的Point推送到List，创建一个新头，并删除最后一个元素（尾部）在每个周期。
这基本上归结为......
snakeBody.removeLast();
snakeBody.push(new Point(xPos, yPos));
作为一个可运行的概念
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.util.LinkedList;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Snake {
public static void main(String[] args) {
new Snake();
}
public Snake() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public static class TestPane extends JPanel {
public enum Direction {
UP, DOWN, LEFT, RIGHT
}
private int xPos, yPos;
private Direction direction = Direction.UP;
private LinkedList<Point> snakeBody = new LinkedList<>();
public TestPane() {
xPos = 100;
yPos = 100;
for (int index = 0; index < 50; index++) {
snakeBody.add(new Point(xPos, yPos));
}
bindKeyStrokeTo("up.pressed", KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0, false), new MoveAction(Direction.UP));
bindKeyStrokeTo("down.pressed", KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0, false), new MoveAction(Direction.DOWN));
bindKeyStrokeTo("left.pressed", KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0, false), new MoveAction(Direction.LEFT));
bindKeyStrokeTo("right.pressed", KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0, false), new MoveAction(Direction.RIGHT));
Timer timer = new Timer(40, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
switch (direction) {
case UP:
yPos--;
break;
case DOWN:
yPos++;
break;
case LEFT:
xPos--;
break;
case RIGHT:
xPos++;
break;
}
if (yPos < 0) {
yPos--;
} else if (yPos > getHeight() - 1) {
yPos = getHeight() - 1;
}
if (xPos < 0) {
xPos--;
} else if (xPos > getWidth() - 1) {
xPos = getWidth() - 1;
}
snakeBody.removeLast();
snakeBody.push(new Point(xPos, yPos));
repaint();
}
});
timer.start();
}
public void bindKeyStrokeTo(String name, KeyStroke keyStroke, Action action) {
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap am = getActionMap();
im.put(keyStroke, name);
am.put(name, action);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(Color.RED);
for (Point p : snakeBody) {
g2d.drawLine(p.x, p.y, p.x, p.y);
}
g2d.dispose();
}
public class MoveAction extends AbstractAction {
private Direction moveIn;
public MoveAction(Direction direction) {
this.moveIn = direction;
}
@Override
public void actionPerformed(ActionEvent e) {
direction = this.moveIn;
}
}
}
}
现在，它没有碰撞检测或其他功能，但你可以移动蛇并且它将自行跟随
答案 1 :(得分：1)
对于蛇式运动，您可以从尾部到头部将每个BodyPart位置移动到前面BodyPart的位置。对于头部而言，前面没有任何部分，因此您必须编写决策代码，无论是简单地移动与之前的部分相同的方向还是基于输入的新方向。然后更新屏幕。