只能移动放置在场景中的最后一个对象

Question

喂！我只能移动放置在场景中的最后一个虚拟对象。当我添加另一个对象时，之前添加的对象保持静态，我无法对其执行任何操作。你能给我一个解决方案来移动、缩放、旋转我想要的对象吗？

Answer 1

鉴于您还没有发布任何代码，因此很难提供准确的答案。

但是，为了跟踪您希望使用的当前 SCNNode，当您加载模型等时，您可以将其存储为变量，例如：

var currentNode: SCNNode!

您还可以在加载模型时使用节点的 name 属性以保持对它的更具体引用。

这是一个这样做的例子：

/// Example Of Loading An SCNScene & Setting It As The Current Node
func loadModel(){

        let modelPath = "Character.scn"

        //1. Get The Reference To Our SCNScene & Get The Model Root Node
        guard let model = SCNScene(named: modelPath),
            let modelObject = model.rootNode.childNode(withName: "Root", recursively: false) else { return }

        //2. Scale It
        modelObject.scale = SCNVector3(0.4, 0.4, 0.4)

        //3. Add It To The Scene & Position It 1.5m Away From The Camera
        augmentedRealityView.scene.rootNode.addChildNode(modelObject)
        modelObject.position = SCNVector3(0, 0, -1.5)

        //4. Set It As The Current Node & Assign A Name
        currentNode = modelObject
        currentNode.name = "Character"

 }

您还可以使用 SCNHitTest 其中：

Looks for SCNGeometry objects along the ray you specify. For each intersection between the ray and and a geometry, SceneKit creates a hit-test result to provide information about both the SCNNode object containing the geometry and the location of the intersection on the geometry’s surface.

这可用于区分哪些节点被击中，例如：

/// Detects A Tap On An SCNNode
///
/// - Parameter gesture: UITapGestureRecognizer
@objc func detectTap(_ gesture: UITapGestureRecognizer){

    //1. Get The Current Touch Point
    let currentTouchPoint = gesture.location(in: self.augmentedRealityView)

    //2a. Perform An SCNHitTest To Detect If An SCNNode Has Been Touched
    guard let nodeHitTest = self.augmentedRealityView.hitTest(currentTouchPoint, options: nil).first else { return }

    if nodeHitTest.node == currentNode{
        print("The Current Node Has Been Touched")
    }

    //Or To See Which Node Has Been Touched
    if nodeHitTest.node.name == "The Model"{
        print("The Model Has Been Touched")
    }
}

另一种处理此问题的方法是将 UITapGestureRecognizer 添加到视图中，并根据结果启用交互，例如以这种方式设置 currentNode 例如：

/// Detects A Tap On An SCNNode & Sets It As The Current Node
///
/// - Parameter gesture: UITapGestureRecognizer
@objc func detectTap(_ gesture: UITapGestureRecognizer){

    //1. Get The Current Touch Point
    let currentTouchPoint = gesture.location(in: self.augmentedRealityView)

    //2a. Perform An SCNHitTest To Detect If An SCNNode Has Been Touched
    guard let nodeHitTest = self.augmentedRealityView.hitTest(currentTouchPoint, options: nil).first else { return }

    //2b. Set It As The Current Node
    currentNode = nodeHitTest.node
}

然后您可以应用逻辑来确保只有 currentNode 移动等：

/// Moves An SCNNode
///
/// - Parameter gesture: UIPanGestureRecognizer
@objc func moveNode(_ gesture: UIPanGestureRecognizer) {

    //1. Get The Current Touch Point
    let currentTouchPoint = gesture.location(in: self.augmentedRealityView)

    //2. If The Gesture State Has Begun Perform A Hit Test To Get The SCNNode At The Touch Location
    if gesture.state == .began{

        //2a. Perform An SCNHitTest To Detect If An SCNNode Has Been Touched
        guard let nodeHitTest = self.augmentedRealityView.hitTest(currentTouchPoint, options: nil).first else { return }

        //2b. Get The SCNNode Result
        if nodeHitTest.node == currentNode{

            //3a. If The Gesture State Has Changed Then Perform An ARSCNHitTest To Detect Any Existing Planes
            if gesture.state == .changed{

                //3b. Get The Next Feature Point Etc
                guard let hitTest = self.augmentedRealityView.hitTest(currentTouchPoint, types: .existingPlane).first else { return }

                //3c. Convert To World Coordinates
                let worldTransform = hitTest.worldTransform

                //3d. Set The New Position
                let newPosition = SCNVector3(worldTransform.columns.3.x, worldTransform.columns.3.y, worldTransform.columns.3.z)

                //3e. Apply To The Node
                currentNode.simdPosition = float3(newPosition.x, newPosition.y, newPosition.z)

            }

        }
    }
}

这应该足以为您指明正确的方向...

只能移动放置在场景中的最后一个对象

Can move only the last object placed in Scene

scenekit

arkit