Libgdx - How to make the dialog fade but not the whole stage?

Question

When I show a Dialog with

someDialog.show(someStage);

The dialog show with default FadeIn action. And the stage fade in too. So it make my background fade along with the stage.

How can I prevent this to happen?

Edit: Here my example code:

In Screen show method:

Texture bg = new Texture(Gdx.files.internal(src));
stage = new Stage(game.getViewport(), batch);
stage.addActor(someDialog) //just normal dialog

render code:

@Override
    public void render(float delta) {
        super.render(delta);
        getBatch().begin();
        getBatch().draw(backgroundTexture, 0, 0, width, height);
        getBatch().end();
        getStage().act(delta);
        getStage().draw();
        time += delta;
    }

I show the dialog when some event trigger:

   dialog.show(getStage());

I have tried to put null as second parameter to the show method

dialog.show(getStage(), null);

and make both stage and dialog not fade in but a want to keep the effect for only dialog or at least not the background.

Answer 1

Stage doesn't clean up the SpriteBatch's color when it's done, so when the loop comes back around, the last-used color is still applied to the sprite batch. In your case, the last used color happens to be the dialog's color.

To fix this, add getBatch().setColor(Color.WHITE); before your getBatch().draw(backgroundTexture, 0, 0, width, height); line.

And I don't think your whole stage is fading. Right now, your background texture has nothing to do with the stage, except that they're both sharing use of the SpriteBatch.