如何通过在屏幕上拖动手指来更改相机位置-SWIFT XCODE

Question

我正在尝试学习ARKIT，并制作一个小型演示应用程序以绘制3D。以下是我编写的代码，到目前为止没有问题：

import UIKit
import ARKit
class ViewController: UIViewController, ARSCNViewDelegate {


    @IBOutlet weak var sceneView: ARSCNView!

    @IBOutlet weak var DRAW: UIButton!
    @IBOutlet weak var DEL: UIButton!

    let config = ARWorldTrackingConfiguration()

    override func viewDidLoad() {
        super.viewDidLoad()

        self.sceneView.session.run(config)
        self.sceneView.delegate = self
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

    func renderer(_ renderer: SCNSceneRenderer, willRenderScene scene: SCNScene, atTime time: TimeInterval) {

        guard let pointOfView = sceneView.pointOfView else {return}
        let transform = pointOfView.transform
        let cameraOrientation = SCNVector3(-transform.m31,-transform.m32,-transform.m33)
        let cameraLocation = SCNVector3(transform.m41,transform.m42,transform.m43)
        let cameraCurrentPosition = cameraOrientation + cameraLocation

        DispatchQueue.main.async {

            if (self.DRAW.isTouchInside){
                let sphereNode  = SCNNode(geometry: SCNSphere(radius: 0.02))
                    sphereNode.position = cameraCurrentPosition
                    self.sceneView.scene.rootNode.addChildNode(sphereNode)
                    sphereNode.geometry?.firstMaterial?.diffuse.contents = UIColor.red
                    print("RED Button is Pressed")
                }else if (self.DEL.isTouchInside){
                    self.sceneView.scene.rootNode.enumerateChildNodes{
                    (node, stop) in
                    node.removeFromParentNode()
                    }
                }else{
                    let pointer = SCNNode(geometry: SCNSphere(radius: 0.01))
                    pointer.name = "pointer"
                    pointer.position = cameraCurrentPosition
                    self.sceneView.scene.rootNode.enumerateChildNodes({(node,_) in
                        if node.name == "pointer"{
                            node.removeFromParentNode()
                        }
                    })
                     self.sceneView.scene.rootNode.addChildNode(pointer)
                    pointer.geometry?.firstMaterial?.diffuse.contents = UIColor.purple
                }
        }
    }

}

func +(left:SCNVector3,right:SCNVector3) -> SCNVector3 {
    return SCNVector3Make(left.x + right.x, left.y + right.y, left.z + right.z)
}

如您所见，我设置了场景并对其进行配置，我创建了一个在按下时进行绘制的按钮，一个以场景中心为中心的指针（或取景器）和一个用于删除插入的节点的按钮。

现在，我希望能够将cameraCurrentPosition移动到与中心不同的位置：如果可能的话，我希望通过触摸屏幕以手指的位置进行移动。如果可能，有人可以帮助我提供代码吗？谢谢：）

Answer 1

[通常来说，您不能以编程方式在ARSCN内移动相机，相机变换是设备相对于虚拟场景的物理位置。

话虽这么说，您可以将用户触摸屏吸引到屏幕的一种方法是使用View Controller中的touchesMoved方法。

override func func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    if let touch = touches.first {
        let translation = touch.location(in: self.view)
        let translationFromCenter = CGPoint(x: translation.x - (0.5 * self.view.frame.width), y: translation.y - (0.5 * self.view.frame.height))

        // add nodes using the main thread
        DispatchQueue.main.async {
            let sphereNode : SCNNode = SCNNode(geometry: SCNSphere(radius: 0.015))
            sphereNode.position = SCNVector3(-1*Float(translationFromCenter.x/1000), -1*Float(translationFromCenter.y/1000), 0)
            sphereNode.geometry?.firstMaterial?.diffuse.contents = UIColor.white
            sceneView.scene.rootNode.addChildNode(sphereNode)  // add point to the scene root
        }
    }
}