Box2d libgdx,有点混淆像素到米的东西

时间:2013-01-08 05:34:15

标签: java box2d libgdx

所以我理解这个概念。想法是box2d或多或少以米为单位工作,所以你需要从像素转换到它。说得通。我正在关注box2d here的教程/介绍。它提到进行转换并为您提供一些示例使用量。现在,这一切都很好,但我发现当我使用这些技术时,调试器框似乎没有呈现它们应该的位置。然而,碰撞确实按预期工作。

在我的GameScreen课程中,这是我如何初始化地面:

ground = new BodyDef();
// set the position half way up the ground
ground.position.set(0,16 * GameScreen.WORLD_TO_BOX);
groundBody = world.createBody(ground);
groundShape = new PolygonShape();
// make the height 16px so it doubles to 32
groundShape.setAsBox(Gdx.graphics.getWidth() * GameScreen.WORLD_TO_BOX, 16.0f * GameScreen.WORLD_TO_BOX);
groundBody.createFixture(groundShape, 0.0f);

我在该屏幕中的渲染方法如下:

public void render(float delta) {
    Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
    camera.update();
    stateTime += Gdx.graphics.getDeltaTime();

    batch.begin();
    batch.draw(background, 0, Gdx.graphics.getHeight() - 512, 512, 512);
    batch.draw(trailingBackground, 512, Gdx.graphics.getHeight() - 512);
    int heightToCover = Gdx.graphics.getHeight() - 512;
    int widthToCover = Gdx.graphics.getWidth();
    for(int w = 0; w < widthToCover; w += 32) {
        for(int h = 0; h < heightToCover; h += 32) {
            batch.draw(lightBackgroundTile, w, h, 32, 32);
        }
    }
    player.update();
    player.render(stateTime, batch);
    batch.end();
    levels.get(currentLevel).render(camera);

    // physics updates
    world.step(1/60f, 6, 2);
    debugRenderer.render(world, camera.combined);
}

这是播放器类的构造函数,因此您可以看到如何设置其碰撞box2d对象。我还粘贴了上面渲染循环中调用的update方法来调整sprite位置。

public Player(int x, int y, World world) {
    super();
    playerTexture = new Texture(Gdx.files.internal("assets/hero.png"));
    init(x, y, 128, 128, playerTexture, false, world);

    bodyDef = new BodyDef();
    bodyDef.type = BodyType.DynamicBody;
    bodyDef.position.set(x * GameScreen.WORLD_TO_BOX, y * GameScreen.WORLD_TO_BOX);
    body = getWorld().createBody(bodyDef);
    collisionBox = new PolygonShape();
    collisionBox.setAsBox(32 * GameScreen.WORLD_TO_BOX, 64 * GameScreen.WORLD_TO_BOX, new Vector2(64 * GameScreen.WORLD_TO_BOX, 64 * GameScreen.WORLD_TO_BOX), 0.0f);

    FixtureDef fixtureDef = new FixtureDef();
    fixtureDef.shape = collisionBox;
    fixtureDef.density = 10f; 
    fixtureDef.friction = 0.4f;
    fixtureDef.restitution = 0f;

    body.createFixture(fixtureDef);
    collisionBox.dispose();

    addFrame(0, 0, 128, 128);
}

public void update() {
    this.setX((int) ((body.getPosition().x) * GameScreen.BOX_TO_WORLD));
    this.setY((int) ((body.getPosition().y) * GameScreen.BOX_TO_WORLD));
}

现在,当我在各种计算,大小等中删除这些静态浮点数的乘法时,碰撞保持正确并显示调试器框。但是将原始像素传递给box2d感觉不对。这里有什么我不知道为什么调试盒没有按原样出现?

1 个答案:

答案 0 :(得分:1)

我喜欢你在做但可能会有所不同。

可能有点矫枉过正,但这是我的jucl端口

jucl/Android - pastebin

然后我只有实用程序类,即:

public class Pixel {

    public static float toMeter(float pixels) {
        return (float)LengthConversions.Pixel2SIf(pixels);
    }

    public static Vector2 toMeter(Vector2 vecPixel) {
        return new Vector2(Pixel.toMeter(vecPixel.x), Pixel.toMeter(vecPixel.y));
    }
}

public class Meter {

    public static final float METERS_PER_PIXEL = (float) LengthConversions.SI_PIXEL;

    public static float toPixel(float meter) {
        return (float)LengthConversions.SI2Pixelf(meter);
    }
}

在我的初始化中:

int graphicsWidth = Gdx.graphics.getWidth();
int graphicsHeight = Gdx.graphics.getHeight();

CAMERA_WIDTH_METERS = Pixel.toMeter(graphicsWidth);
CAMERA_HEIGHT_METERS = Pixel.toMeter(graphicsHeight);

然后在我的游戏类中(比如你的Player类)。在我的情况下,这是一个弹球游戏,所以我有Flipper,Ball,Bumper等。我有一个@Override render()方法,我将精灵与物理体同步。

这是一个示例文件..它很乱,但可能会有所帮助。

Pinball Engine Class file