[英]Java “Asteroids” Like Game - Slowing Down Ship
因此,我有一個Java搖擺應用程序,其中有一個太空船,該宇宙飛船獲取旋轉角度,然后在該方向上加速(繞其軸旋轉並移動到船頭所在的位置)。 我遇到的麻煩是,當船舶指向與先前方向相反的方向時,它會減速。
如果您查看圖像,您會發現當我嘗試通過完全相反的方向旋轉來補償我的速度時,速度會增加,而我需要做的就是在飛船駛過的情況下降低速度補償以前的速度。
例1:
import java.util.Set;
/**
* Created by griffin on 12/7/2015.
*/
public class Example1 extends JPanel {
public enum Input {
ROTATE_LEFT,
ROTATE_RIGHT,
UP,
DOWN
}
private final int B_WIDTH = 640;
private final int B_HEIGHT = 480;
private Set<Input> inputs;
Ship player = new Ship(320, 240);
public Example1() {
initExample1();
}
private void initExample1() {
inputs = new HashSet<>(25);
setFocusable(true);
setBackground(Color.BLACK);
setPreferredSize(new Dimension(B_WIDTH, B_HEIGHT));
addKeyBinding("rotate-left", KeyEvent.VK_A, Input.ROTATE_LEFT);
addKeyBinding("rotate-right", KeyEvent.VK_D, Input.ROTATE_RIGHT);
addKeyBinding("up", KeyEvent.VK_W, Input.UP);
addKeyBinding("down", KeyEvent.VK_S, Input.DOWN);
Timer timer = new Timer(40, new ActionListener() {
@Override
public void actionPerformed(ActionEvent actionEvent) {
if (inputs.contains(Input.ROTATE_LEFT)) {
player.angle -= 5;
}
if (inputs.contains(Input.UP)) {
player.thrust = true;
player.moveForwards();
}
else
player.moveForwards();
if (inputs.contains(Input.ROTATE_RIGHT)) {
player.angle += 5;
}
player.checkAngle();
player.screenWrap();
repaint();
}
});
timer.start();
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(Color.WHITE);
g2d.drawString("Speed " + (int) player.speed, 15, 15);
AffineTransform old = AffineTransform.getTranslateInstance(player.x, player.y);
old.rotate(Math.toRadians(player.angle), player.getWidth() / 2, player.getHeight() / 2);
g2d.setTransform(old);
g2d.drawImage(player.ship, 0, 0, this);
Toolkit.getDefaultToolkit().sync();
}
private void addKeyBinding(String name, int keyCode, Input input) {
InputMap inputMap = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap actionMap = getActionMap();
inputMap.put(KeyStroke.getKeyStroke(keyCode, 0, false), name + ".pressed");
actionMap.put(name + ".pressed", new InputAction(input, true));
inputMap.put(KeyStroke.getKeyStroke(keyCode, 0, true), name + ".released");
actionMap.put(name + ".released", new InputAction(input, false));
}
private class InputAction extends AbstractAction {
private Input input;
private boolean pressed;
public InputAction(Input input, boolean pressed) {
this.input = input;
this.pressed = pressed;
}
@Override
public void actionPerformed(ActionEvent e) {
if (pressed) {
inputs.add(input);
} else {
inputs.remove(input);
}
}
}
}
船:
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
/**
* Created by griffin on 12/7/2015.
*/
public class Ship {
float directionX, directionY;
boolean thrust = false;
int x, y;
float speed = 1;
int angle = 0, vAngle = 0;
BufferedImage ship;
private String path = "rocketc.png";
public Ship(int x, int y) {
this.x = x;
this.y = y;
getImage();
}
private void getImage() {
try {
ship = ImageIO.read(new File(path));
} catch (Exception e) {
e.printStackTrace();
}
}
public int getWidth() {
return ship.getWidth();
}
public int getHeight() {
return ship.getHeight();
}
public void moveForwards() {
directionX = (float) (Math.cos(Math.toRadians(vAngle))) * speed;
directionY = (float) (Math.sin(Math.toRadians(vAngle))) * speed;
if (thrust) {
speed++;
vAngle = angle;
thrust = false;
}
x -= directionX;
y -= directionY;
}
public void checkAngle () {
if (angle > 360) {
angle = 0;
}
if (angle < 0) {
angle = 360;
}
}
public void screenWrap () {
if (x > 640) {
x = 0;
}
if (x < 0) {
x = 640;
}
if (y > 480) {
y = 0;
}
if (y < 0) {
y = 480;
}
}
}
您可能現在已經知道了這一點,但是在檢查是否按下向上鍵時,尚未將player.thrust
設置回false
。
if (inputs.contains(Input.UP)) {
player.thrust = true;
player.moveForwards();
}
else{
player.thrust = false; // added this line
player.moveForwards();
}
另外,如果要拖動(即,不按向上鍵時減速),則可以在Ship.moveForwards()
中Ship.moveForwards()
speed
:
if (thrust) {
speed++;
vAngle = angle;
thrust = false;
}
else{ // added this block
speed--;
}
您可以用不同的值來增加/減少speed
,以得到不同的加速度/阻力。
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