除非Android应用程序暂停，否则精灵不会显示-LibGDX

Question

Here is the code: http://hastebin.com/ugufakeyap.java

When I run this, the sprite "aspectRatios" is not displayed on the screen. But when I pause the program by pressing my home button and then resuming the program, it displays the sprite onto the screen. Why is this? It's really annoying.

Answer 1

you need to call camera.update(); after changing position. My best guess is that libGDX automatically updates the camera on resume.

public void create () {
    batch = new SpriteBatch();
    txt = new Texture(Gdx.files.internal("test2.png"));
    aspectRatios = new Sprite(txt);
    aspectRatios.setPosition(0,0);
    //aspectRatios.setSize(100,100);

    camera = new OrthographicCamera();
    viewport = new StretchViewport(1080,1920,camera);

    camera.position.set(camera.viewportWidth/2,camera.viewportHeight/2,0);
    camera.update();
    viewport.apply();
    //batch.setProjectionMatrix(camera.combined);
    Gdx.input.setInputProcessor(this);
}

You would normally update the batch projection matrix there as well but you do it every frame in the render method anyway.

Answer 2

Some people helped me on the libGDX irc channel . It turns out that I wasn't calling

viewport.update(width, height, centerCamera);

(Thanks to Xoppa )

And (according to ASneakyFox ): "you have to assume that the android device isnt going to be conveniently the size you want, itll call resize when the app opens up or changes orientation so you can modify your layout to be the dimensions of the screen (ie change the viewport)"

Here is the updated version of the code: http://hastebin.com/olivopocix.java