物体在当前面向方向的旋转和移动;Java

Question

所以我试图在java中构建一个自上而下的太空射击游戏。

我是一个新手，但我已经很好地掌握了它，完美地制作pong。我的主要问题是，我似乎不能降低旋转。

我希望能够在方向键上按向右或向左键，并有一个基本的矩形，在用户输入的方向上围绕其中心旋转。

设置好后，我希望能够按箭头键前进或后退，使其朝着当前所面向的方向移动。

到目前为止，我所尝试的一切都影响了框架中的所有内容，而不仅仅是单个对象。从as2开始，旋转和对象在java中是非常不同的。

谁能帮我解释一下我该怎么做?

package spaceroyalgame;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.geom.AffineTransform;

public class SpaceRoyalGame extends JPanel implements KeyListener {
        static double shipRotation=0, shipRotationSpeed=0, shipSpeed=0, TOPSPEED= 20;
        static int shipy=50, shipx=50, shipWidth = 10, shipHeight = 20;
        static int WorldWidth = 700, WorldHeight = 700;
        static boolean slowdown = true;
    public static void main(String[] args) throws InterruptedException {
        SpaceRoyalGame game = new SpaceRoyalGame();
        JFrame frame = new JFrame();
        frame.add(game);
        frame.setSize(WorldWidth,WorldHeight);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.addKeyListener(game);

        while(true){
            game.moveShip();
            game.repaint();
            Thread.sleep(10);
        }
    }

    public void moveShip(){
        if (shipSpeed != 0) {
            shipx += shipSpeed;
        }
        if (shipRotationSpeed != 0) {
            shipRotation += shipRotationSpeed;
        }
    }

    public void paint (Graphics g){
        super.paint(g);
        setBackground(Color.black);
        Graphics2D g2d = (Graphics2D) g;
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);
        g.setColor(Color.white);
        Rectangle ship = new Rectangle(shipx,shipy,100,50);
        g2d.rotate(Math.toRadians(shipRotation));
        g2d.draw(ship);
        g2d.fill(ship);

    }
    @Override
    public void keyPressed(KeyEvent e) {
        int keyCode = e.getKeyCode();
        slowdown = false;
        if (keyCode == KeyEvent.VK_W) {
            //System.out.println("W is pressed");
            shipSpeed = -2;
        }
        if (keyCode == KeyEvent.VK_S) {
            //System.out.println("S is pressed");
            shipSpeed = 2;
        }
        if (keyCode == KeyEvent.VK_A) {
            System.out.println("A is pressed");
            shipRotationSpeed = 1;
            shipRotation += shipRotationSpeed * (shipSpeed/TOPSPEED);
        }
        if (keyCode == KeyEvent.VK_D) {
            System.out.println("D is pressed");
            shipRotationSpeed = -1;
            shipRotation += shipRotationSpeed * (shipSpeed/TOPSPEED);
        }
    }
    @Override
    public void keyTyped(KeyEvent e) {
    }
    @Override
    public void keyReleased(KeyEvent e) {
        shipRotationSpeed = 0;
        shipSpeed = 0;
    }
}

Answer 1

尝试使用矢量。因为"A"one_answers"D"键会修改你当前的角度，所以你应该保留一个变量来跟踪角度。

从:

x += speed * cos(θ)
y += speed * sin(θ)

如果你想加速/减速:

Δx = speed * cos(θ) * Δt + 1/2 * acceleration * Δt^2
Δy = speed * * sin(θ) * Δt + 1/2 * acceleration * Δt^2

Δt是最后一帧之间的时间。

这可能值得看看物理/运动学