Libgdx How to set viewport position?

Question

I know that in libgdx a stage uses a viewport which defines the camera. I want to render a stage just on a small square on my screen. I tried using a customized viewport but I only managed to set it's size. I also tried using setPosition(int screenX, int screenY) method, but it seems that the viewport is always centered on the middle of the screen no matter what I try. Does anyone know how to set a viewport's position on the screen?

Answer 1

Your problem in my opinion is not in setting viewport position but in updating it - you've got to center your camera when viewport updating

    stage = new Stage();
    viewport = new ExtendViewport(WIDTH, HEIGHT);
    viewport.setScreenPosition(500, 500); //I'm setting viewport's position

    ...

    @Override
    public void render(float delta) 
    {
        ...

        viewport.update(currentWindowWidth, currentWindowHeight, true); //here I'm updateing it with setting camera center

        ...
    }

Compare

void update(int screenWidth, int screenHeight, boolean centerCamera)

and

void update(int screenWidth, int screenHeight)

which calls the update version above with false as default