SpriteBatch fade transition

package net.dermetfan.someLibgdxTests.screens;

import net.dermetfan.someLibgdxTests.tween.ColorAccessor;
import aurelienribon.tweenengine.BaseTween;
import aurelienribon.tweenengine.Tween;
import aurelienribon.tweenengine.TweenCallback;
import aurelienribon.tweenengine.TweenManager;

import com.badlogic.gdx.Game;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.Screen;
import com.badlogic.gdx.graphics.Color;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.graphics.Pixmap;
import com.badlogic.gdx.graphics.Pixmap.Format;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;

public class TransitionTest implements Screen {

    private SpriteBatch batch;
    private OrthographicCamera cam;
    private TweenManager tweenManager;

    private boolean transition;
    private Texture transitionTexture;
    private Color transitionColor;

    @Override
    public void render(float delta) {
        Gdx.gl.glClearColor(1, 0, 0, 1);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
        batch.begin();

        batch.setProjectionMatrix(cam.combined);

        // draw your stuff here

        // draw the black over all of it
        if(transition) {
            tweenManager.update(delta);
            batch.setColor(transitionColor);
            batch.draw(transitionTexture, cam.position.x - cam.viewportWidth / 2, cam.position.y - cam.viewportHeight / 2, cam.viewportWidth, cam.viewportHeight);
        }

        batch.end();
    }

    private void startTransition() {
        transition = true;
        Tween.to(transitionColor, ColorAccessor.A, 1).target(1).setCallback(new TweenCallback() {

            @Override
            public void onEvent(int type, BaseTween<?> source) {
                ((Game) Gdx.app.getApplicationListener()).setScreen(new Menu());
            }

        }).start(tweenManager);
    }

    @Override
    public void resize(int width, int height) {
        startTransition();
    }

    @Override
    public void show() {
        batch = new SpriteBatch();
        cam = new OrthographicCamera(Gdx.graphics.getWidth(), Gdx.graphics.getHeight());

        // you could also just load a black texture the normal way
        Pixmap pixmap = new Pixmap(1, 1, Format.RGB565);
        pixmap.setColor(Color.BLACK);
        pixmap.fill();
        transitionTexture = new Texture(pixmap);
        pixmap.dispose();

        transitionColor = new Color(0, 0, 0, 0);

        tweenManager = new TweenManager();
        Tween.registerAccessor(Color.class, new ColorAccessor());
    }

    @Override
    public void hide() {
        dispose();
    }

    @Override
    public void pause() {
    }

    @Override
    public void resume() {
    }

    @Override
    public void dispose() {
        batch.dispose();
        transitionTexture.dispose();
    }

}