java - 塔防 : bullet math

Question

我正在使用 Slick2D 库用 Java 制作塔防游戏。我的子弹数学有问题。现在子弹将在敌人当前的 X,Y 坐标之后射击 - 但由于当子弹到达 X,Y 时敌人已经移动，因此它会落后。除了加快子弹速度之外，您知道如何解决这个问题吗？项目符号数学位于项目符号类的底部。

public class Bullets implements GameObject {
private ArrayList<Bullet> bulletList = new ArrayList<Bullet>();
Enemy enemy = new Enemy();
BasicTower basicTower = new BasicTower();
public Shape bulletCircle = null;
public boolean collides = false;
public int bulletCount;

public Bullets() throws SlickException {
}


@Override
public Vector2f getPosition() {
    return null;
}

@Override
public void init(GameContainer gc, StateBasedGame stateBasedGame) throws SlickException {
}

@Override
public void render(GameContainer gc, StateBasedGame stateBasedGame, Graphics g) throws SlickException {
    for (int i = 0; i < bulletList.size(); i++) {
        Bullet bullet = bulletList.get(i);
        bulletCircle = new Circle(bullet.location.getX(),bullet.location.getY(),10);
        if (bulletCircle.intersects( enemy.playerRectangle )){
            bulletCount++;
            bulletList.remove( i );
            collides = true;
        }else{
            collides = false;
        }
        g.setColor( red );
        g.fill(bulletCircle);
    }


}

@Override
public void update(GameContainer gc, StateBasedGame stateBasedGame, int delta) throws SlickException {
    //Update the bullet's position.
    Input input = gc.getInput();
    //enemy.update(gc, stateBasedGame, delta);
    for (int i = 0; i < bulletList.size(); i++) {
        Bullet bullet = bulletList.get(i);
        bullet.move();
    }
}

public void addNewBullet2(float x1, float y1, float x2, float y2) {
    bulletList.add(new Bullet(x1*64+48,y1*64+48, x2, y2));
}


class Bullet {
    float startX = 0;
    float startY = 0;
    float destX = 0;
    float destY = 0;
    Point location = new Point(0, 0);
    float speed; //how fast this moves.
    float dx;
    float dy;


    public Bullet(float startX, float startY, float destX, float destY) {
        this.startX = startX;
        this.startY = startY;
        location.setLocation(startX, startY);
        this.destX = destX;
        this.destY = destY;
        recalculateVector(destX, destY);
    }

    public void recalculateVector(float destX, float destY) {
        float rad = (float) (Math.atan2(destX - startX, startY - destY));
        //Can set different speeds here, if you wanted.
        speed = 5;
        this.dx = (float) Math.sin(rad) * speed;
        this.dy = -(float) Math.cos(rad) * speed;
    }

    public void move() {
        float x = location.getX();
        float y = location.getY();
        x += dx;
        y += dy;
        location.setLocation(x, y);
    }
}

Answer 1

这里只是一个线性代数问题。您的目标是 P0 点，即您开始射击敌人时所在的位置。但相反，你需要指出子弹到达他们的时间。所以你需要敌人的速度、子弹的速度和射击者的距离来获得正确点的坐标。

但是，由于数学可能会变得棘手(例如，如果目标不沿着一条线移动)，您可以尝试让子弹跟随目标，这当然会导致曲线轨迹。