libGDX Box2d ApplyTorque() funktioniert nicht

[temi]

Hallo zusammen,
ich experimentiere gerade etwas mit Box2d herum und möchte den Körper rotieren. Mit den auskommentierten Zeilen funktioniert es, mit applyTorque() nicht. Was mache ich falsch?

public class PhysicsModel
{
    private final World world = new World(new Vector2(0,0), true);
    private Body body;
    private final KeyboardController keyboardController;
    private float torque = 0;

    public PhysicsModel(final KeyboardController controller)
    {
        this.keyboardController = controller;

        BodyDef bodyDef = new BodyDef();
        bodyDef.type = BodyDef.BodyType.DynamicBody;
        bodyDef.position.set(0,0);

        body = world.createBody(bodyDef);

        PolygonShape shape = new PolygonShape();
        shape.setAsBox(2,1);

        FixtureDef fixtureDef = new FixtureDef();
        fixtureDef.shape = shape;
        fixtureDef.density = 1f;

        body.createFixture(shape, 0.0f);

        shape.dispose();
    }

    public World getWorld()
    {
        return world;
    }

    public void step(float delta)
    {
        if(keyboardController.isLeft())
        {
            torque += 0.1f;
            //body.setTransform(body.getPosition(), body.getAngle() + 0.01f);
        }

        if(keyboardController.isRight())
        {
            torque -= 0.1f;
            //body.setTransform(body.getPosition(), body.getAngle() - 0.01f);
        }

        if(keyboardController.isUp())
        {
            Vector2 vec = new Vector2((float)Math.cos(body.getAngle()), (float)Math.sin(body.getAngle()));

            body.applyForceToCenter(vec, true);
        }

        body.applyTorque(torque, true);

        world.step(delta, 3, 3);
    }

    @Override
    protected void finalize() throws Throwable
    {
        world.dispose();

        super.finalize();
    }
}

public class PhysicsModel
{
    private final World world = new World(new Vector2(0,0), true);
    private Body body;
    private final KeyboardController keyboardController;
    private float torque = 0;

    public PhysicsModel(final KeyboardController controller)
    {
        this.keyboardController = controller;

        BodyDef bodyDef = new BodyDef();
        bodyDef.type = BodyDef.BodyType.DynamicBody;
        bodyDef.position.set(0,0);

        body = world.createBody(bodyDef);

        PolygonShape shape = new PolygonShape();
        shape.setAsBox(2,1);

        FixtureDef fixtureDef = new FixtureDef();
        fixtureDef.shape = shape;
        fixtureDef.density = 1f;

        body.createFixture(shape, 0.0f);

        shape.dispose();
    }

    public World getWorld()
    {
        return world;
    }

    public void step(float delta)
    {
        if(keyboardController.isLeft())
        {
            torque += 0.1f;
            //body.setTransform(body.getPosition(), body.getAngle() + 0.01f);
        }

        if(keyboardController.isRight())
        {
            torque -= 0.1f;
            //body.setTransform(body.getPosition(), body.getAngle() - 0.01f);
        }

        if(keyboardController.isUp())
        {
            Vector2 vec = new Vector2((float)Math.cos(body.getAngle()), (float)Math.sin(body.getAngle()));

            body.applyForceToCenter(vec, true);
        }

        body.applyTorque(torque, true);

        world.step(delta, 3, 3);
    }

    @Override
    protected void finalize() throws Throwable
    {
        world.dispose();

        super.finalize();
    }
}

Zur Vervollständigung noch die render Methode:

    @Override
    public void render ()
    {
        physics.step(Gdx.graphics.getDeltaTime());

        Gdx.gl.glClearColor(0, 0, 0, 1);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

        debugRenderer.render(physics.getWorld(), camera.combined);
    }

 

[temi]

Ok, ich habe den Fehler gefunden. Der Code war teilweise von einem Tutorial herauskopiert und ist hier (zumindest für meinen Fall) fehlerhaft:

        FixtureDef fixtureDef = new FixtureDef();
        fixtureDef.shape = shape;
        fixtureDef.density = 1f; // Masse

        body.createFixture(shape, 0.0f); // verwendet die fixtureDef nicht und überschreibt die Masse mit Null.

Ohne Masse kein Drehmoment.