SceneKit对象在其边界框处而不是沿着网格物体碰撞

Question

我正在使用“DAE”模型作为SCNGeometry。

试图将它用作物理体形状：

    let url = Bundle.main.url(forResource: "art.scnassets/half", withExtension: "dae")
    let sceneSource = SCNSceneSource(url: url!, options: nil)
    let tubeGeometry = (sceneSource?.entryWithIdentifier("Cube-mesh", withClass: SCNGeometry.self ))! as SCNGeometry

    tubeNode = SCNNode(geometry: tubeGeometry)
    tubeNode.position = SCNVector3(0, 1, 0)
    tubeNode.eulerAngles = SCNVector3Make(1.5, 2, 0)

    let tubeShape = SCNPhysicsShape(geometry: tubeGeometry, options: nil)
    let tubeBody = SCNPhysicsBody(type: .static, shape: tubeShape)
    tubeNode.physicsBody = tubeBody
    scene.rootNode.addChildNode(tubeNode)

不要察觉几何对象属性（边，面等）。看似立方体感知立方体。因此，球与一个不是我的物体的无形平面相撞，但必须向内倾斜，如下面的截图：

任何想法/建议为什么？请帮我解决这个问题......

提前致谢！