现在我正在制作经典游戏小行星。我已经让船使用箭头键移动360度。然而，当我试图以该角度将球射出船外时，它们仅以45度的增量离开。我认为这意味着我在球类中的数学有问题：
public Ball(double ballAngle){
angle = ballAngle;
xRatio = Math.cos((angle + 90) * 3.14 / 180);
yRatio = Math.sin((angle + 90) * 3.14 / 180);
xChange = xRatio * speed;
yChange = yRatio * speed;
}
public void update(){
x = (int) Math.round(x + xChange);
y = (int) Math.round(y + yChange);
}
然而，我似乎无法找到发生的事情。我已经尝试通过逐步打印值来调试它，但仍然无法解决它。这是我的其余代码，你需要看到它。
主要游戏类：
package Asteroids;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.util.ArrayList;
@SuppressWarnings("serial")
public class Asteroids extends JPanel implements KeyListener{
public final static int BOX_WIDTH = 600;
public final static int BOX_HEIGHT = 600;
public final static int UPDATE_RATE = 300;
public final static double shipSpeed = 1;
ArrayList<Ball> balls = new ArrayList<Ball>();
int i = 0;
int ballCount = 0;
boolean spawn = false;
Ship ship = new Ship(BOX_WIDTH / 2,BOX_HEIGHT / 2);
public Asteroids(){
//Set window size
setPreferredSize(new Dimension(BOX_WIDTH,BOX_HEIGHT));
//Start game thread
Thread gameThread = new Thread() {
public void run(){
while(true){
ship.update();
for (int j=0; j<ballCount; j++){
balls.get(j).update();
}
if(spawn){
i++;
}
if(i % 100 == 0){
balls.add(new Ball(ship.getAngle()));
ballCount ++;
}
repaint();
try {Thread.sleep(1000 / UPDATE_RATE);}
catch (InterruptedException ex) {}
}
}
};
gameThread.start();
}
@Override
public void paintComponent(Graphics g) {
g.setColor(Color.black);
g.fillRect(0, 0, BOX_WIDTH, BOX_HEIGHT);
for (int j=0; j<ballCount; j++){
balls.get(j).draw(g);
}
ship.draw(g);
}
public void keyPressed(KeyEvent e){
if(e.getKeyCode() == KeyEvent.VK_LEFT){
ship.setSpeed(-shipSpeed);
}
if(e.getKeyCode() == KeyEvent.VK_RIGHT){
ship.setSpeed(shipSpeed);
}
if(e.getKeyCode() == KeyEvent.VK_SPACE){
spawn = true;
}
}
public void keyReleased(KeyEvent e) {
if(e.getKeyCode() == KeyEvent.VK_LEFT){
ship.setSpeed(0);
}
if(e.getKeyCode() == KeyEvent.VK_RIGHT){
ship.setSpeed(0);
}
if(e.getKeyCode() == KeyEvent.VK_SPACE){
spawn = false;
}
}
public void keyTyped(KeyEvent e) {}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
//Create Frame
JFrame frame = new JFrame("ASTEROIDS");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Asteroids asteroids = new Asteroids();
frame.setContentPane(asteroids);
frame.setSize(BOX_WIDTH,BOX_HEIGHT);
frame.pack();
frame.addKeyListener(asteroids);
frame.setVisible(true);
}
});
}
public int getBoxHeight(){
return BOX_HEIGHT;
}
public int getBoxWidth(){
return BOX_WIDTH;
}
}
船级：
package Asteroids;
import java.awt.Color;
import java.awt.Graphics;
import java.util.Random;
public class Ship {
Random rng = new Random();
int r = rng.nextInt(256);
int g = rng.nextInt(256);
int b = rng.nextInt(256);
Color color = new Color(r,g,b);
double speed = 0;
double angle = 0;
final static int shipLength = 20;
final static int shipAngle = 40;
static int x;
static int y;
int point1x;
int point2x;
int point3x;
int point1y;
int point2y;
int point3y;
public Ship(int xPos, int yPos){
x = xPos;
y = yPos;
point1x = x;
point2x = (int) Math.round( x - (Math.tan(shipAngle * 6.28 / 360) * shipLength));
point3x = (int) Math.round( x + (Math.tan(shipAngle * 6.28 / 360) * shipLength));
point1y = y - shipLength;
point2y = y + shipLength;
point3y = y + shipLength;
}
public void update(){
angle = angle + speed;
if(angle < 0){
angle = angle + 360;
}
else if(angle >= 360){
angle = angle - 360;
}
}
public void draw(Graphics g) {
g.setColor(color);
point1x = x - (int) Math.round( Math.sin(angle * 6.28 / 360) * shipLength);
point2x = x + (int) Math.round( Math.sin((angle + shipAngle) * 6.28 / 360) * shipLength);
point3x = x + (int) Math.round( Math.sin((angle - shipAngle) * 6.28 / 360) * shipLength);
point1y = y + (int) Math.round( Math.cos(angle * 6.28 / 360) * shipLength);
point2y = y + (int) Math.round( Math.cos((angle + 180 + shipAngle) * 6.28 / 360) * shipLength);
point3y = y + (int) Math.round( Math.cos((angle - 180 - shipAngle) * 6.28 / 360) * shipLength);
int xpoints[] = {point1x, point2x, point3x};
int ypoints[] = {point1y, point2y, point3y};
int npoints = 3;
g.fillPolygon(xpoints, ypoints, npoints);
}
public void setSpeed(double s){
speed = s;
}
public static int getX(){
return x;
}
public static int getY(){
return y;
}
public double getAngle(){
return angle;
}
}
球类：
package Asteroids;
import java.awt.Color;
import java.awt.Graphics;
public class Ball {
int x = Ship.getX();
int y = Ship.getY();
double angle;
double xRatio;
double yRatio;
double xChange;
double yChange;
final static int speed = 1;
final static int diameter = 5;
public Ball(double ballAngle){
angle = ballAngle;
xRatio = Math.cos((angle + 90) * 3.14 / 180);
yRatio = Math.sin((angle + 90) * 3.14 / 180);
xChange = xRatio * speed;
yChange = yRatio * speed;
}
public void update(){
x = (int) Math.round(x + xChange);
y = (int) Math.round(y + yChange);
}
public void draw(Graphics g) {
g.setColor(Color.white);
g.fillOval(x - diameter/2, y - diameter/2, diameter, diameter);
}
}
答案 0 :(得分：2)
我怀疑它有一个舍入错误。您将x和y存储为int基元，然后向其添加双精度数，并将其存储回int中。如果您将x和y更改为双打，然后仅在显示位置之前将它们舍入，则不应该出现此问题