ios - 如何通过在屏幕上拖动手指来更改相机位置 - Swift

Question

我正在尝试学习 ARKIT 并制作一个小型演示应用程序以在 3D 中绘图。以下是我写的代码，目前没有任何问题:

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
    }

    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，我设置了场景并进行了配置，我创建了一个按下时进行绘制的按钮、一个位于场景中心的指针(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点:如果可能的话，我想通过触摸屏幕来移动它，以获取手指的位置。如果可能的话，有人可以帮我处理代码吗？

Answer 1

一般来说，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。

话虽如此，您可以将用户触摸到屏幕的一种方法是在 View Controller 中使用 touchesMoved 方法。

var touchRoots: [SCNNode] = [] // list of root nodes for each set of touches drawn

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    // get the initial touch event
    if let touch = touches.first {
        guard let pointOfView = self.sceneView.pointOfView else { return }
        let transform = pointOfView.transform // transformation matrix
        let orientation = SCNVector3(-transform.m31, -transform.m32, -transform.m33) // camera rotation
        let location = SCNVector3(transform.m41, transform.m42, transform.m43) // location of camera frustum
        let currentPostionOfCamera = orientation + location // center of frustum in world space
        DispatchQueue.main.async {
            let touchRootNode : SCNNode = SCNNode() // create an empty node to serve as our root for the incoming points
            touchRootNode.position = currentPostionOfCamera // place the root node ad the center of the camera's frustum
            touchRootNode.scale = SCNVector3(1.25, 1.25, 1.25)// touches projected in Z will appear smaller than expected - increase scale of root node to compensate
            guard let sceneView = self.sceneView else { return }
            sceneView.scene.rootNode.addChildNode(touchRootNode) // add the root node to the scene
            let constraint = SCNLookAtConstraint(target: self.sceneView.pointOfView) // force root node to always face the camera
            constraint.isGimbalLockEnabled = true // enable gimbal locking to avoid issues with rotations from LookAtConstraint
            touchRootNode.constraints = [constraint] // apply LookAtConstraint

            self.touchRoots.append(touchRootNode)
        }
    }
}

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 {
            guard let touchRootNode = self.touchRoots.last else { return }
            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
            touchRootNode.addChildNode(sphereNode)  // add point to the active root
        }
    }
}

注意:解决方案仅处理单点触摸，但扩展示例以添加多点触摸支持足够简单。/p>