Swift3 导致缩放三维模型的SCNLookat约束

在进一步测试和评估之后，似乎是SCNLookAtConstraint导致了问题。基本上，因为它删除了2指平移手势，它导致了一些奇怪的捏和滚动手势行为。有人知道如何解决这个问题吗

UPDATE: 

---

你是如何变焦照相机的？我在你的代码中看不到移动相机的任何地方。当前使用默认行为允许相机控制。它为我处理手势，但当使用1个手指旋转和2个手指挤压手势时，它允许我的对象缩小到从视图中消失的点。

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) { 
  let quaternion = sceneView.pointOfView?.orientation
  let position = sceneView?.pointOfView?.position
  print("Orientation: ((quaternion?.x),(quaternion?.y),(quaternion?.z),(quaternion?.w)) Position: ((position?.x),(position?.y),(position?.z)") 
}

func setupScene() {
    let scene = SCNScene()
    self.sceneView.scene = scene

    let camera = SCNCamera()
    let cameraNode = SCNNode()
    cameraNode.camera = camera
    cameraNode.position = SCNVector3(x: -1.0, y: 0.0, z: -1.0)
    cameraNode.boundingBox.max = SCNVector3(x: 2, y: 2, z: 2)
    cameraNode.boundingBox.min = SCNVector3(x: 0.1, y: 0.1, z: 0.1)

    let centerNode = SCNNode()
    centerNode.position = SCNVector3(x: 0.0, y: 0.0, z: 0.0)

    let light = SCNLight()
    let lightNode = SCNNode()
    light.type = .ambient
    light.color = UIColor.white
    lightNode.light = light

    scene.rootNode.addChildNode(cameraNode)
    scene.rootNode.addChildNode(centerNode)
    scene.rootNode.addChildNode(lightNode)

    cameraNode.constraints = [SCNLookAtConstraint(target: centerNode)]
    sceneView.pointOfView = cameraNode

}