如何创建 libgdx 主菜单屏幕 [关闭]

Question

我是 java 和 libgdx 的新手，我想创建一个主菜单屏幕，有人能给我一个简单的例子吗？

Answer 1

您的要求非常广泛，它涉及许多元素，例如创建按钮、皮肤、设置表格等。无论如何，您应该为此使用 Screens，添加舞台并将演员添加到舞台。最终，您需要将侦听器添加到您的按钮演员以切换屏幕。这是我为您制作的：

public class TestScreen implements Screen{

    private SpriteBatch batch;
    protected Stage stage;
    private Viewport viewport;
    private OrthographicCamera camera;
    private TextureAtlas atlas;
    protected Skin skin;

    public TestScreen()
    {
        atlas = new TextureAtlas("skin.atlas");
        skin = new Skin(Gdx.files.internal("skin.json"), atlas);

        batch = new SpriteBatch();
        camera = new OrthographicCamera();
        viewport = new FitViewport(Constants.WorldWidth, Constants.WorldHeight, camera);
        viewport.apply();

        camera.position.set(camera.viewportWidth / 2, camera.viewportHeight / 2, 0);
        camera.update();

        stage = new Stage(viewport, batch);    
    }


    @Override
    public void show() {
        //Stage should controll input:
        Gdx.input.setInputProcessor(stage);

        //Create Table
        Table mainTable = new Table();
        //Set table to fill stage
        mainTable.setFillParent(true);
        //Set alignment of contents in the table.
        mainTable.top();

        //Create buttons
        TextButton playButton = new TextButton("Play", skin);
        TextButton optionsButton = new TextButton("Options", skin);
        TextButton exitButton = new TextButton("Exit", skin);

        //Add listeners to buttons
        playButton.addListener(new ClickListener(){
            @Override
            public void clicked(InputEvent event, float x, float y) {
                ((Game)Gdx.app.getApplicationListener()).setScreen(new PlayScreen());
            }
        });
        exitButton.addListener(new ClickListener(){
            @Override
            public void clicked(InputEvent event, float x, float y) {
                Gdx.app.exit();
            }
        });

        //Add buttons to table
        mainTable.add(playButton);
        mainTable.row();
        mainTable.add(optionsButton);
        mainTable.row();
        mainTable.add(exitButton);

        //Add table to stage
        stage.addActor(mainTable);
    }

    @Override
    public void render(float delta) {
        Gdx.gl.glClearColor(.1f, .12f, .16f, 1);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

        stage.act();
        stage.draw();
    }

    @Override
    public void resize(int width, int height) {
        viewport.update(width, height);
        camera.position.set(camera.viewportWidth / 2, camera.viewportHeight / 2, 0);
        camera.update();
    }

    @Override
    public void pause() {

    }

    @Override
    public void resume() {

    }

    @Override
    public void hide() {

    }

    @Override
    public void dispose() {
        skin.dispose();
        atlas.dispose();
    }
}

我称之为的方式是稍微改变初始类。

//Let the class extend from game
public class MyGame extends Game()
{
    //Delete everything in it and leave a create() with a single line
    @Override
    public void create() {
    setScreen(new MenuScreen());
    }
}

当然，要使上述代码正常工作，您需要设置Skin 和Atlas 来绘制按钮。但是，您可以只添加图像和字体并手动创建按钮。无论如何，我只是在 answered a question 那里深入创建 Skin 和 Atlas。

编辑 尽管已经询问了菜单类的示例，但用户询问者实际上只需要知道如何在屏幕之间切换。有点尴尬，但幸运的是，编写上面的代码只花了几分钟；）。

您始终可以使用Gdx.app.getApplicationListener 从任何地方访问ApplicationListener。您可以将此投射到Game 以访问setScreen。

((Game)Gdx.app.getApplicationListener()).setScreen(new GameScreen());

或者您可以手动传递初始 Game 对象或 applicationListener。确保新屏幕接受游戏对象。

public class MenuScreen
{
    private Game gameObject;
    public MenuScreen(Game gameObject)
    {
        this.gameObject = gameObject;
    }
    private void someMethod()
    {
         //Switches to a new MenuScreen... 
         //useless in most cases but you get the idea
         gameObject.setScreen(new MenuScreen(gameObject);
    }
}