iOS ARKit 手势拖动、旋转、缩放3D模型

基于官方ARKit文档里的示例代码

Swift4.2核心手势代码如下

    override public func viewDidLoad() {
        super.viewDidLoad()
        
        sceneView.addGestureRecognizer(UIPinchGestureRecognizer.init(target: self, action: #selector(pinchDo)))//缩放
        sceneView.addGestureRecognizer(UIPanGestureRecognizer.init(target: self, action: #selector(panGuestDo)))
        sceneView.addGestureRecognizer(UITapGestureRecognizer.init(target: self, action: #selector(tapGuestDo)))
    }

    @objc func pinchDo(_ pinch: UIPinchGestureRecognizer) {//捏合缩放
        guard let curObj = objM.lastUsedObject else { return }
        
        
        if pinch.state == .began {//每次捏合手势开始重新获取
            beginPinchScale = pinch.scale//手势开始时获取当前模型的scale
            beginObjScale = curObj.scale.x//手势开始时获取手势的比例scale
        }
        
        if pinch.state == .changed {
            //计算, 当前手势scale除以手势开始时的scale, 以开始时模型的scale为基准相乘, 实现圆润的放大缩小效果
            var scale = beginObjScale*Float(pinch.scale/beginPinchScale)
            scale = scale<0.5 ? 0.5 : scale
            scale = scale>2 ? 2 : scale
            curObj.scale = SCNVector3.init(scale, scale, scale)
        }
    }
    
    @objc func panGuestDo(_ GG: UIPanGestureRecognizer) {//拖动手势
        guard let curObj = objM.lastUsedObject else { return }

        let location = GG.location(in: sceneView)
        let velocityPoint = GG.velocity(in: sceneView)

        switch GG.state {
        case .changed:
            if let touchedObj = virtualObject(at: location, inSceV: sceneView) {//位移
                objM.translate(touchedObj, in: sceneView, basedOn: location, instantly: true)//位移方法
                objM.lastUsedObject = touchedObj//自定义模型管理类
            }else{//旋转
                let xx = Float(velocityPoint.x/5000)//支持空白处水平x轴滑动旋转
                let yy = Float(velocityPoint.y/5000)//支持空白处垂直y轴滑动旋转
                curObj.eulerAngles.y += abs(xx) > abs(yy) ? xx : -yy
            }
        case .ended:
            return
        default:
            return
        }
    }

    var beginObjScale: Float = 1
    var beginPinchScale: CGFloat = 1
    @IBOutlet var sceneView: ARSCNView!