java - Box2D Android Studio 绘制倒置形状

Question

我正在使用 Android Studio 和 LibGDX 创建一个碰撞测试游戏，我拥有游戏集所需的一切，但是我想在 Box2D 中创建一个像这样的倒三角形，显然，它不会看起来像但这张图片是给你一个例子

但是当我运行它时，它看起来像这样:

我尝试更改 Box2D 中代码的顺序，但它不会创建倒三角形，如下所示:

private Fixture createcollisionFixture(Body collisionBody) {
        Vector2[] vertices = new Vector2[3];
        vertices[0] = new Vector2(-0.5f, -0.5f);
        vertices[1] = new Vector2(0.5f, -0.5f);
        vertices[2] = new Vector2(0, 0.5f);
        PolygonShape shape = new PolygonShape();
        shape.set(vertices);
        Fixture fix = collisionBodyBody.createFixture(shape, 1);
        shape.dispose();
        return fix;
    }

我将其更改为:

private Fixture createcollision2Fixture(Body collision2Body) {
        Vector2[] vertices = new Vector2[3];
        vertices[2] = new Vector2(0, 0.5f);
        vertices[1] = new Vector2(0.5f, -0.5f);
        vertices[0] = new Vector2(-0.5f, -0.5f);
        PolygonShape shape = new PolygonShape();
        shape.set(vertices);
        Fixture fix = collision2Body.createFixture(shape, 1);
        shape.dispose();
        return fix;

    }

但它一直作为第二张图片加载，而不是像倒三角形，我该如何解决这个问题？我们将不胜感激。

Answer 1

问题不在于 Box2D，而在于您用来绘制三角形的坐标。无论您以什么顺序将它们传递给 Fixture，它们都会生成如下三角形:

如果你想旋转三角形，你必须传递另一组坐标，如下所示:

最后你的代码应该是这样的:

    ...

    Vector2[] vertices = new Vector2[3];
    vertices[2] = new Vector2(-0.5, 0.5f);
    vertices[1] = new Vector2(0.5f, 0.5f);
    vertices[0] = new Vector2(0.5f, -0.5f);

    ...