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Java LibGDX 无法在启用物理体和重力的情况下移动

转载 作者：行者123 更新时间：2023-12-01 09:34:34 26 4
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我确实需要一些帮助，但我陷入了困境。我试图在一个简单的游戏中使一个 block 成为地面，另一个 block 落到它上面，然后可能弹起一点，但能够向左或向右移动盒子以从第一个 block 上掉下来。谁能帮我解决这个问题吗？

对于任何对答案感兴趣的人，感谢 PoprostuRonin 和 dermetfan 的 YouTube 视频，我能够得到我正在寻找的结果，您可以在您的项目中尝试以下代码，只需更改 Sprite 纹理即可。

private Box2DDebugRenderer debugRenderer;
private OrthographicCamera camera;
private float spriteSpeed = 500000;
private World world;
private Sprite playersprite;
private Sprite groundsprite;
private Body playerBody;
private Body groundbody;
private Vector2 movement = new Vector2();
private Array<Body> tmpBodies = new Array<Body>();

public TestState(GameStateManager gsm) {
    super(gsm);

    Gdx.input.setInputProcessor(this);

    batch = new SpriteBatch();

    debugRenderer = new Box2DDebugRenderer();
    camera = new OrthographicCamera();

    // Sprites
    playersprite = new Sprite(new Texture("badlogic.jpg"));
    groundsprite = new Sprite(new Texture("ground-tiles-01.gif"));

    // World
    world = new World(new Vector2(0, -9.8f), true);

    // Player Sprite
    // Body definition
    BodyDef bodyDef = new BodyDef();
    bodyDef.type = BodyType.DynamicBody;
    bodyDef.position.set(0, 200); //1m

    PolygonShape shape = new PolygonShape();
    shape.setAsBox(10, 10);

    // Fixture definition
    FixtureDef fixtureDef = new FixtureDef();
    fixtureDef.shape = shape;
    fixtureDef.density = 2.5f; //2.5kg
    fixtureDef.friction = 0; //0-1
    fixtureDef.restitution = .75f; //0-1

    playerBody = world.createBody(bodyDef); 
    playerBody.createFixture(fixtureDef);
    playerBody.setUserData(playersprite);
    playersprite.setSize(20, 20);
    playersprite.setOrigin(playersprite.getWidth() / 2, playersprite.getHeight() / 2);
    shape.dispose();

    // Ground Sprite
    // Body definition
    BodyDef groundbodyDef = new BodyDef();
    groundbodyDef.type = BodyType.StaticBody;
    groundbodyDef.position.set(0, 0); //1m

    PolygonShape groundshape = new PolygonShape();
    groundshape.setAsBox(groundsprite.getHeight() / 2, groundsprite.getWidth() / 2);

    // Fixture definition
    FixtureDef groundfixtureDef = new FixtureDef();
    groundfixtureDef.shape = groundshape;
    groundfixtureDef.density = 100; //2.5kg
    groundfixtureDef.friction = .25f; //0-1
    groundfixtureDef.restitution = 0; //0-1

    groundbody = world.createBody(groundbodyDef); 
    groundbody.createFixture(groundfixtureDef);
    groundbody.setUserData(groundsprite);
    groundsprite.setSize(groundsprite.getHeight(), groundsprite.getWidth());
    groundsprite.setOrigin(groundsprite.getWidth() / 2, groundsprite.getHeight() / 2);

    groundshape.dispose();
}

@Override
public void update(float delta) {
    camera.viewportWidth = Gdx.graphics.getWidth();
    camera.viewportHeight = Gdx.graphics.getHeight();
}

@Override
public void render() {
    Gdx.gl.glClearColor(50 / 255f, 213 / 255f, 237 / 255f, 1);
    Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

    debugRenderer.render(world, camera.combined);
    batch.setProjectionMatrix(camera.combined);
    world.step(Gdx.graphics.getDeltaTime(), 6, 2);

    playerBody.applyForceToCenter(movement, true);

    batch.begin();
    world.getBodies(tmpBodies);
    for (Body body : tmpBodies){
        if (body.getUserData() != null && body.getUserData() instanceof Sprite) {
            Sprite sprite = (Sprite) body.getUserData();
            sprite.setPosition(body.getPosition().x - sprite.getWidth() / 2, body.getPosition().y - sprite.getHeight() / 2);
            sprite.setRotation(body.getAngle() * MathUtils.radiansToDegrees);
            sprite.draw(batch);
        }
    }
    batch.end();

    camera.position.set(playerBody.getPosition().x, playerBody.getPosition().y, 0);
    camera.update();

}

@Override
public void dispose() {
    world.dispose();
    playersprite.getTexture().dispose();
    groundsprite.getTexture().dispose();
}

@Override
public boolean keyDown(int keycode) {
    switch (keycode) {
    case Keys.DPAD_LEFT:
        movement.x = -spriteSpeed;
        break;
    case Keys.DPAD_RIGHT:
        movement.x = spriteSpeed;
        break;
    case Keys.DPAD_UP:
        movement.y = spriteSpeed;
        break;
    case Keys.DPAD_DOWN:
        movement.y = -spriteSpeed;
    }
    return true;
}

@Override
public boolean keyUp(int keycode) {
    switch (keycode) {
    case Keys.DPAD_LEFT:
    case Keys.DPAD_RIGHT:
        movement.x = 0;
        break;
    case Keys.DPAD_UP:
    case Keys.DPAD_DOWN:
        movement.y = 0;
    }
    return true;
}

最佳答案

您的代码是有效的，问题是数字。

你的 body 质量很大，20480公斤。重力是颠倒的，因为你要求它:

world = new World(new Vector2(0, -1000f), true);

-1000，它低于 0，所以它是倒置的，大数字(在你的“星球”上是 1000，在地球上是 9.8)会导致物体不太可控。

更改值:

float spriteSpeed = 60000;
...
world = new World(new Vector2(0, 9.8F), true);
...
fixtureDef.density = 1;
fixtureDef2.density = 1;

你会注意到现在 body 是可控的(它甚至可以飞)。玩弄这些数字并学习一些基本的物理规则，以了解您在做什么。

Sprite 和 body 位置已同步，但未正确对齐。使用此代码完成第一步，使纹理与主体对齐。

sprite.setCenter(body.getPosition().x, body.getPosition().y);
groundsprite.setCenter(ground.getPosition().x, ground.getPosition().y);

但是旋转呢

groundsprite.setOriginCenter();
sprite.setOriginCenter();

groundsprite.setRotation(ground.getAngle() * MathUtils.radDeg);
sprite.setRotation(body.getAngle() * MathUtils.radDeg);

这很简单，因为您的对象是单个纹理，我们可以简单地将其对齐在中心，但随着对象变得更加复杂，需要更改代码。

关于Java LibGDX 无法在启用物理体和重力的情况下移动，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/39113809/

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