Libgdx-Box2D：将Physics Body Editor加载器蒙版附加到动态纹理

Question

I have a texture of a circle, which gets drawn to a new position when a touch drag occurs. It isn't set up as a body.

I have made a physics map using Aurelien Ribon's Physics Body Editor Loader GUI to the circle's upper and lower part, and I'd like to draw that mask over the texture's position, and to its new position when a drag occurs.

How can I do this? In my create method I initialize the variables, the mask gets drawn to the texture's initial position, but when I move it the mask stays at the circle's initial position.

Here's my code:

Create() method:

 //... rest of the method ommited for clarity

    karika = gameWorld.getKarika();

    World world = new World(new Vector2(0, 0), false);


Box2DDebugRenderer renderer = new Box2DDebugRenderer();
    BodyEditorLoader karikaLoader = new BodyEditorLoader(Gdx.files.internal("data/collision-masks/karika.json"));

    BodyDef karikaDef = new BodyDef();
    karikaDef.type = BodyType.DynamicBody;
    karikaDef.position.set(karika.getPosition().x, karika.getPosition().y);
    karikaDef.angle = karika.getRotation();

    Body karikaBody = world.createBody(karikaDef);

    FixtureDef karikaFixture = new FixtureDef();
    karikaFixture.density = 0.5f;
    karikaFixture.friction = 0.8f;
    karikaFixture.restitution = 0.6f;

    karikaLoader.attachFixture(karikaBody, "karika", karikaFixture, karika.getWidth());
    Vector2 karikaBodyOrigin = karikaLoader.getOrigin("karika", karika.getWidth()).cpy();

    //rest of the method ommited for clarity

My render() method:

 //...
    batch.begin();
    batch.draw(karikaTexture, karika.getPosition().x, karika.getPosition().y, karika.getWidth() / 2, karika.getHeight() / 2, karika.getWidth(), karika.getHeight(), 1, 1, karika.getRotation(), 0, 0, karikaTexture.getWidth(), karikaTexture.getHeight(), false, false);
    batch.end();
renderer.render(world, cam.combined);
    world.step(1 / 60f, 6, 2);
    //...

The texture that is being drawn in the render method is my circle's texture. As said before, I haven't set that up as a body, only the collision mask.

What I'd like to do, is attach the mask to the texture, and keep up with it's position, for example when I drag the circle, the mask should stay on the circle.

Answer 1

Look into the DebugRenderer . It works very well, and does precisely what you're asking.

Here's how to use it.

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

And here's a more thorough tutorial .

I recommend you assign your circle's position using physics object's position rather than trying to assign the physics object to your texture's position.

In your code, it looks like you create your karikaBody using the current position of karika , but the karikaBody position is never being updated after that. So your "collision mask" (your physics body) position never changes.