Libgdx box2d应用dyanamic_body.applyForceToCenter()不工作。

Question

我在box2dworld中创建了1个动态和1个静态体，我想通过制作一个斜坡使动态体在水平方向上移动，但它根本不起作用。这是我的代码。

public class Box2dBodyTest implements ApplicationListener
{
    World world;
    Box2DDebugRenderer debugRenderer;
    private OrthographicCamera camera;

    @Override
    public void create() 
    {
        camera = new OrthographicCamera();
        camera.setToOrtho(false);

        world = new World(new Vector2(0, -10), true); 

        debugRenderer = new Box2DDebugRenderer();

        createDynamicBody();

        createStaticBody();
    }

    private void createDynamicBody()
    {
        BodyDef bodyDef = new BodyDef();
        // We set our body to dynamic, for something like ground which doesn't move we would set it to StaticBody
        bodyDef.type = BodyType.DynamicBody;
        // Set our body's starting position in the world
        bodyDef.position.set(100, 300);

        // Create our body in the world using our body definition
        Body body = world.createBody(bodyDef);

        // Create a circle shape and set its radius to 6
        CircleShape circle = new CircleShape();
        circle.setRadius(6f);

        // Create a fixture definition to apply our shape to
        FixtureDef fixtureDef = new FixtureDef();
        fixtureDef.shape = circle;
        fixtureDef.density = 0.5f; 
        fixtureDef.friction = 0.4f;
        fixtureDef.restitution = 0.6f; // Make it bounce a little bit

        // Create our fixture and attach it to the body
        Fixture fixture = body.createFixture(fixtureDef);

        body.applyForceToCenter(10.0f, 0.0f, true);

        // Remember to dispose of any shapes after you're done with them!
        // BodyDef and FixtureDef don't need disposing, but shapes do.
        circle.dispose();
    }


    private void createStaticBody()
    {
        // Create our body definition
        BodyDef groundBodyDef = new BodyDef();  
        // Set its world position
        groundBodyDef.position.set(new Vector2(0, 10));  

        // Create a body from the defintion and add it to the world
        Body groundBody = world.createBody(groundBodyDef);  

        // Create a polygon shape
        PolygonShape groundBox = new PolygonShape();  
        // Set the polygon shape as a box which is twice the size of our view port and 20 high
        // (setAsBox takes half-width and half-height as arguments)
        groundBox.setAsBox(camera.viewportWidth, 10.0f);
        // Create a fixture from our polygon shape and add it to our ground body  
        groundBody.createFixture(groundBox, 0.0f); 
        // Clean up after ourselves
        groundBox.dispose();
    }


    @Override
    public void render()
    {
        Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);

        camera.update();

        world.step(1/60f, 6, 2);

        debugRenderer.render(world, camera.combined);
    }
}

我已经搜索了很多，并尝试我最好的解决这个问题，通过box2d教程等，但没有得到解决。请大家帮帮我。先谢谢你了。

Answer 1

我建议你在处理Box2d的时候使用现实的尺寸。Box2d假设的比例是每米一个像素，这对大多数程序员来说不是很实用。当你定义你的圆形夹具时，你设置半径为6.0f，这意味着 Box2d创建一个直径为12米或39英尺的圆。 . 这是巨大的。我建议你看看 本视频. 当我为同样的问题而苦恼时，它真的帮助了我。