How to zoom in and out on a stage in libgdx Scene2d?

Question

I am making a 2d game using libgdx and am adding hexagon shaped actors to a group which is then added to a stage. For a normal camera you can use camera.zoom in the render method to zoom in and out along with camera.translate to pan around the world.

I have been getting the camera used by the stage using stage.getCamera() and I can still call stage.getcamera().translate however there is no stage.getCamera().zoom option.

Here is my code:

//import statements

public class HexGame implements ApplicationListener{

private Stage stage;

private Texture hexTexture;
private Group hexGroup;

private int screenWidth;
private int screenHeight;


@Override
public void create() {

    hexTexture = new Texture(Gdx.files.internal("hex.png"));

    screenHeight = Gdx.graphics.getHeight();
    screenWidth = Gdx.graphics.getWidth();

    stage = new Stage(new ScreenViewport());

    hexGroup = new HexGroup(screenWidth,screenHeight,hexTexture);

    stage.addActor(hexGroup);
}

@Override
public void dispose() {
    stage.dispose();
    hexTexture.dispose();
}

@Override
public void render() {
    Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
    stage.act(Gdx.graphics.getDeltaTime());
    stage.draw();

    handleInput();
    stage.getCamera().update();

}


private void handleInput() {

    if (Gdx.input.isKeyPressed(Input.Keys.LEFT)) {
        stage.getCamera().translate(-3, 0, 0);
    }
    if (Gdx.input.isKeyPressed(Input.Keys.RIGHT)) {
        stage.getCamera().translate(3, 0, 0);
    }
    if (Gdx.input.isKeyPressed(Input.Keys.DOWN)) {
        stage.getCamera().translate(0, -3, 0);
    }
    if (Gdx.input.isKeyPressed(Input.Keys.UP)) {
        stage.getCamera().translate(0, 3, 0);
    }

    //This is the part that doesn't work
    /*
    if (Gdx.input.isKeyPressed(Input.Keys.Z)) {
        stage.getCamera().zoom += 0.02;
    }
    */

    }



@Override
public void resize(int width, int height) {
    stage.getViewport().update(width, height);
}

@Override
public void pause() {
}

@Override
public void resume() {
}


}

Any help is appreciated, and if there is anything else wrong with my code please let me know, I'm new to libgdx. Thanks

Answer 1

Zoom is available in OrthographicCamera class and by default Stage class create a OrthographicCamera

/** Creates a stage with a {@link ScalingViewport} set to {@link Scaling#stretch}. The stage will use its own {@link Batch}
     * which will be disposed when the stage is disposed. */
    public Stage () {
        this(new ScalingViewport(Scaling.stretch, Gdx.graphics.getWidth(), Gdx.graphics.getHeight(), new OrthographicCamera()),
            new SpriteBatch());
        ownsBatch = true;
    }

So what you need is to cast your camera to OrthographicCamera:

((OrthographicCamera)stage.getCamera()).zoom += 0.02f;