LibGDX making viewport larger than screen

Question

I've been struggling with how to use and set up Viewports in LibGDX for quite some time. I want to be able to render everything like its on a display that is 1920x1080 and have it scale to fit the display its on, and I need some help getting to work like that.
This is what I want it to look like (taken from a computer with a 1920x1080 monitor), but when I run the same code on my laptop which is 1440x800, it looks like this. I apologize for the poor photo of a screen, I couldn't get it to take a screenshot of the game running for whatever reason, but it shows that the top of the display remains unused, and that not everything is being fit to the display. This is the main code running the show:

public class Main extends Game {
    ...
    public void create() {
        ...         
        Gdx.graphics.setFullscreenMode(Gdx.graphics.getDisplayMode());

        //last
        this.setScreen(new MainMenu(this));
    }

    public void render() {
        super.render(); //important!
    }
    ...
}

And then the MainMenu class

public class MainMenu implements Screen{
    ...

    public MainMenu(final Main game) {
        this.game = game;
        cam = new OrthographicCamera();
        cam.setToOrtho(false, 1920, 1080);

        ...
    }

    @Override
    public void render(float delta) {
        Gdx.gl.glClearColor(0.025f, .025f, 0.025f, 1);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
        cam.update();
        game.batch.setProjectionMatrix(cam.combined);

        ...

        if(Gdx.input.isKeyPressed(Keys.ESCAPE)) {
            Gdx.app.exit();
        }
    }

    ...
}

How would I implement a Viewport or something of the like to get it to look the same on the smaller screen as it does on the larger? Any help is really appreciated! If you want to see the code that I left out for brevity, its all on my GitHub. Thanks again!

Answer 1

That didn't take me long, hopefully someone will learn from me though, ha ha.

Turns out when you use the camera with fixed height and width like that, it does fill up the whole monitor, but the cameras width DOES NOT equal the value returned by Gdx.graphics.getWidth(). Because of this all my code was rendering like it was being compressed because it was referencing the width returned by Gdx.graphics, and not the camera.viewportWidth.

Lesson learned: Gdx.graphics.getWidth() can and will change depending on device and cam.veiwportWidth wont. Oops!