Question

我已经为Android设备制作了一个小行星游戏，但是很难注意到玩家站在一个方向但是在另一个轻微移动的方向发射子弹。我查看了代码，它只在玩家加速和旋转时才会发生。不是当玩家只是在旋转时。我希望这段代码足以告诉你一些关于它的建议。

当子弹没有时，玩家正在朝正确的方向旋转。我尝试将更新功能放在不同的顺序中，但这也没有帮助。我没有看到问题是什么，因为在射击时，玩家类每次都会使用玩家的弧度创建一个子弹。所以我认为它与子弹被射击时弧度没有更新有关。

private void initForces() {
    maxSpeed = 300;
    acceleration = 200;
    friction = 10;
}

private void initRotationSpeed() {
    // Radians are used to determine the angle the player points in
    radians = MathUtils.PI / 2;

    rotationSpeed = 3;
}

public void shoot() {
    final int MAX_BULLETS = 4;
    if (bullets.size() == MAX_BULLETS || isHit()) return;
    bullets.add(new Bullet(x, y, radians));
}

   public void update(float dt) {
        if (updateCheckIfPlayerHit(dt)) {
            return;
        }

        updateCheckExtraLives();

        // Forces
        updateAcceleration(dt);
        updateRotationSpeed(dt);
        updateTurning(dt);
        updateFriction(dt);

        // Set shape
        setShape();

        // Screen wrap
        wrap();
    }

   private void updateTurning(float dt) {
        // Turning: Tilt the screen to left or right to rotate the ship
        final float ROTATION_SENSITIVITY = 3;
        if (left || Gdx.input.getAccelerometerX() > ROTATION_SENSITIVITY) {
            radians += rotationSpeed * dt;
        }
        else if (right || Gdx.input.getAccelerometerX() < -ROTATION_SENSITIVITY) {
            radians -= rotationSpeed * dt;
        }
    }

    private void updateRotationSpeed(float dt) {
        x += dx * dt;
        y += dy * dt;
    }

    private void updateAcceleration(float dt) {
        // Accelerating
        if (up || Gdx.input.isTouched() && Gdx.input.getX() > 0 && Gdx.input.getX() < Gdx.graphics.getWidth() / 2) {
            dx += MathUtils.cos(radians) * acceleration * dt;
            dy += MathUtils.sin(radians) * acceleration * dt;
        }
    }

    private void updateFriction(float dt) {
        // Friction
        float vector = (float)Math.sqrt(dx * dx + dy * dy);
        if (vector > 0) {
            dx -= (dx / vector) * friction * dt;
            dy -= (dy / vector) * friction * dt;
        }

        if (vector > maxSpeed) {
            dx = (dx / vector) * maxSpeed;
            dy = (dy / vector) * maxSpeed;
        }
    }

Bullet.java

package com.mygdx.entities;

import com.badlogic.gdx.graphics.glutils.ShapeRenderer;
import com.badlogic.gdx.math.MathUtils;

public class Bullet extends SpaceObject {

    private float lifeTime;
    private float lifeTimer;

    private boolean remove;

    Bullet(float x, float y, float radians) {
        this.x = x;
        this.y = y;
        this.radians = radians;

        float speed = 350;
        dx = MathUtils.cos(radians) * speed;
        dy = MathUtils.sin(radians) * speed;

        width = height = 2;

        lifeTimer = 0;
        lifeTime = 1;
    }

    public boolean shouldRemove() {
        return remove;
    }

    public void update(float dt) {

        updateRotationSpeed(dt);
        wrap();

        updateLifeTime(dt);
    }

    private void updateRotationSpeed(float dt) {
        x += dx * dt;
        y += dy * dt;
    }

    private void updateLifeTime(float dt) {
        // How long time the bullet is supposed to live
        lifeTimer += dt;
        if (lifeTimer > lifeTime) {
            remove = true;
        }
    }

    public void draw(ShapeRenderer shapeRenderer) {
        shapeRenderer.setColor(1, 1, 1, 1);
        shapeRenderer.begin(ShapeRenderer.ShapeType.Line);
        shapeRenderer.circle(x - width / 2, y - height / 2, width / 2);
        shapeRenderer.end();
    }

}

要与播放器一起拍摄代码：

    if (Gdx.input.justTouched() &&
                    Gdx.input.getX() > Gdx.graphics.getWidth() / 2 &&
                    Gdx.input.getX() < Gdx.graphics.getWidth()) {
        player.shoot();
    }

Answer 1

我的问题的答案是我忘记了一点数学。所以在Bullet构造函数中我没有播放器在x或y方向的速度，所以我在Player类中创建了两个静态变量，并将它们设置为等于播放器的dx和dy在更新转速功能。这两个变量都是浮点数。

private void updateRotationSpeed(float dt) {
    x += dx * dt;
    y += dy * dt;

    dxStatic = dx;
    dyStatic = dy;
}

public static float getPlayerDeltaX() {
    return dxStatic;
}

public static float getPlayerDeltaY() {
    return dyStatic;
}

在Bullet类的构造函数中，我需要添加：

Bullet(float x, float y, float radians) {
    this.x = x;
    this.y = y;
    this.radians = radians;

    float speed = 350;
    dx = speed * MathUtils.cos(radians) + Player.getPlayerDeltaX();
    dy = speed * MathUtils.sin(radians) + Player.getPlayerDeltaY();

    width = height = 2;

    lifeTimer = 0;
    lifeTime = 1;
}

所以这就是导致子弹向略有不同方向移动的原因。

编辑：或者你可以在Bullet构造函数中添加一些浮点变量并接受播放器的dx和dy，因为每次在播放器类中创建一个子弹。就我而言，它至少是。这可能是一个更好的选择。

Bullet(float x, float y, float playerDeltaX, float playerDeltaY, float radians) {
    this.x = x;
    this.y = y;
    this.radians = radians;

    float speed = 350;
    dx = speed * MathUtils.cos(radians) + playerDeltaX;
    dy = speed * MathUtils.sin(radians) + playerDeltaY;

    width = height = 2;

    lifeTimer = 0;
    lifeTime = 1;

}

小行星libGDX余弦和正弦旋转方程，以错误的角度射击子弹

1 个答案: