android - 在 libGDX 中重复滚动背景？

Question

我对 Java、libGDX 和 android 开发还很陌生，我浏览了许多教程视频，现在决定自己冒险。我知道，有风险。
无论如何，我希望有一个非常简单的游戏，并且在这个游戏中我希望背景可以无限滚动。很像 Flappy Bird 或 Doodle Jump。
就目前而言，我有一个 5760 x 1080 的大图像，我像这样水平滚动它:

public void render() {
    Gdx.gl.glClearColor(1, 1, 1, 1);
    Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
    camera.translate(10, 0);
    camera.update();

    batch.setProjectionMatrix(camera.combined);
    batch.begin();
    sprite.draw(batch);
    batch.end();
}

我相信您会知道，这会以每次渲染 10 像素的速率沿背景移动相机。问题是，图像的大小有限，所以我希望它从头开始重新启动图像。
我已经查看了如何执行此操作，但对这一切感到非常困惑，所以我想我会试着问一个具体的问题。

除了创建我的纹理和 spriteBatch 之外，实际上没有其他代码，所以正如我所说，到目前为止是一件非常简单的事情。

我怎样才能让背景图片重新加载并一直持续下去？

Answer 1

LibGDX 有这样的类:

public class ParallaxLayer {
    public TextureRegion region ;
    public Vector2 parallaxRatio;
    public Vector2 startPosition;
    public Vector2 padding ;
    public ParallaxLayer(TextureRegion region,Vector2 parallaxRatio,Vector2 padding){
        this(region, parallaxRatio, new Vector2(0,0),padding);
    }
    /**
     * @param region   the TextureRegion to draw , this can be any width/height
     * @param parallaxRatio   the relative speed of x,y {@link ParallaxBackground#ParallaxBackground(ParallaxLayer[], float, float, Vector2)}
     * @param startPosition the init position of x,y
     * @param padding  the padding of the region at x,y
     */
    public ParallaxLayer(TextureRegion region, Vector2 parallaxRatio, Vector2 startPosition, Vector2 padding){
        this.region  = region;
        this.parallaxRatio = parallaxRatio;
        this.startPosition = startPosition;
        this.padding = padding;
    }
}

并且:

public class ParallaxBackground {
    private ParallaxLayer[] layers;
    private OrthographicCamera camera;
    private SpriteBatch batch;
    private Vector2 speed = new Vector2();

    /**
     * @param layers  The  background layers
     * @param width   The screenWith
     * @param height The screenHeight
     * @param speed A Vector2 attribute to point out the x and y speed
     */
    public ParallaxBackground(ParallaxLayer[] layers,float width,float height,Vector2 speed){
        this.layers = layers;
        this.speed.set(speed);
        camera = new OrthographicCamera(width, height);
        batch = new SpriteBatch();
    }

    public void render(float delta){
        this.camera.position.add(speed.x*delta,speed.y*delta, 0);
        for(ParallaxLayer layer:layers){
            batch.setProjectionMatrix(camera.projection);
            batch.begin();
            float currentX = - camera.position.x*layer.parallaxRatio.x % ( layer.region.getRegionWidth() + layer.padding.x) ;

            if( speed.x < 0 )currentX += -( layer.region.getRegionWidth() + layer.padding.x);
            do{
                float currentY = - camera.position.y*layer.parallaxRatio.y % ( layer.region.getRegionHeight() + layer.padding.y) ;
                if( speed.y < 0 )currentY += - (layer.region.getRegionHeight()+layer.padding.y);
                do{
                    batch.draw(layer.region,
                            -this.camera.viewportWidth/2+currentX + layer.startPosition.x ,
                            -this.camera.viewportHeight/2 + currentY +layer.startPosition.y);
                    currentY += ( layer.region.getRegionHeight() + layer.padding.y );
                }while( currentY < camera.viewportHeight);
                currentX += ( layer.region.getRegionWidth()+ layer.padding.x);
            }while( currentX < camera.viewportWidth);
            batch.end();
        }
    }
}

您可以将这些类复制/粘贴到您的项目中。然后，要使用，请执行以下操作:

ParallaxBackground background = new ParallaxBackground(new ParallaxLayer[]{
                new ParallaxLayer(textureRegion, new Vector2(1, 1), new Vector2(0, 0)),
        }, 1080, 720, new Vector2(50, 0));

然后在您的render() 方法中执行background.render(delta)。

您可以向 ParallaxBackground 构造函数添加更多层以满足您的需要。