AR对象在RealityKit中无法正确锚定或调整大小

如何解决AR对象在RealityKit中无法正确锚定或调整大小

我有一个AR场景，其中有两个对象，一头棕色母牛，一头黑色母牛。它们都应该在场景中显示，并且相隔一定距离。我最初只有一头棕色的母牛，那头母牛太大了。我改变了一些我不记得的东西，现在我的场景是从奶牛的内部出来的，我无法离开奶牛的尸体。当我这样做时，它似乎在移动。我认为问题是因为[最小界限]为正数，但我不确定。我还为母牛设置了z轴。如何在产卵时使母牛稍微矮一点并在离我约5-7码的地方？

  import UIKit
  import RealityKit
  import ARKit

class ViewController: UIViewController {

@IBOutlet var arView: ARView!

override func viewDidLoad() {
    super.viewDidLoad()
 
    arView.session.delegate = self
    
    showModel()
    overlayCoachingView()
    setupARView()
    
    arView.addGestureRecognizer(UITapGestureRecognizer(target: self,action: 
#selector(handleTap(recognizer:))))
    
}

func showModel(){
    
    let anchorEntity = AnchorEntity(plane: .horizontal,minimumBounds:[0.7,0.7])
    
    let entity = try! Entity.loadModel(named: "COW_ANIMATIONS")
    entity.setParent(anchorEntity)
    
    arView.scene.addAnchor(anchorEntity)
    

}
func overlayCoachingView () {
    
    let coachingView = ARCoachingOverlayView(frame: CGRect(x: 0,y: 0,width: 
arView.frame.width,height: arView.frame.height))
    
    coachingView.session = arView.session
    coachingView.activatesAutomatically = true
    coachingView.goal = .horizontalPlane
    
    view.addSubview(coachingView)
    
}
    
    // Load the "Box" scene from the "Experience" Reality File
   // let boxAnchor = try! Experience.loadBox()
    
    // Add the box anchor to the scene
    //arView.scene.anchors.append(boxAnchor)

func setupARView(){
    arView.automaticallyConfigureSession = false
    let configuration = ARWorldTrackingConfiguration()
    configuration.planeDetection = [.horizontal,.vertical]
    configuration.environmentTexturing = .automatic
    arView.session.run(configuration)
}

//object placement

@objc
func handleTap(recognizer: UITapGestureRecognizer){
    let location = recognizer.location(in:arView)
    
    let results = arView.raycast(from: location,allowing: .estimatedPlane,alignment: .horizontal)
    
    if let firstResult = results.first {
        let anchor = ARAnchor(name: "COW_ANIMATIONS",transform: firstResult.worldTransform)
        arView.session.add(anchor: anchor)
    } else {
        print("Object placement failed - couldn't find surface.")
        
        //cow animations
        let robot = try! ModelEntity.load(named: "COW_ANIMATIONS")
        let anchor = AnchorEntity()
        anchor.children.append(robot)
        arView.scene.anchors.append(anchor)

        robot.playAnimation(robot.availableAnimations[0].repeat(duration: .infinity),transitionDuration: 0.5,startsPaused: false)
        
        //start cow animation
        let brownCow = try! ModelEntity.load(named: "COW_ANIMATIONS")
        let blackCow = try! ModelEntity.load(named: "Cow")

        brownCow.position.x = -1.0
        blackCow.position.x = 1.0

        
        brownCow.setParent(anchor)
        blackCow.setParent(anchor)
        arView.scene.anchors.append(anchor)

        let cowAnimationResource = brownCow.availableAnimations[0]
        let horseAnimationResource = blackCow.availableAnimations[0]

        brownCow.playAnimation(cowAnimationResource.repeat(duration: .infinity),transitionDuration: 1.25,startsPaused: false)

        blackCow.playAnimation(horseAnimationResource.repeat(duration: .infinity),transitionDuration: 0.75,startsPaused: false)
        
        //end cow animations

 
    func placeObject(named entityName: String,for anchor: ARAnchor)  {
      let entity = try! ModelEntity.loadModel(named: entityName)
    
      entity.generateCollisionShapes(recursive: true)
      arView.installGestures([.rotation,.translation],for: entity)
    
    
      let anchorEntity = AnchorEntity(anchor: anchor)
      anchorEntity.addChild(entity)
      arView.scene.addAnchor(anchorEntity)
    
    
   }
   }
extension ViewController: ARSessionDelegate {
func session( session: ARSession,didAdd anchors: [ARAnchor]) {
for anchor in anchors {
    if let anchorName = anchor.name,anchorName == "COW_ANIMATIONS" {
        placeObject(named: anchorName,for: anchor)
    }  }
}
}

解决方法

第一步

在RealityKit中，如果将模型与其个人锚点绑定在一起（如果一个锚点仅持有一个模型），则有两种缩放方法：

cowEntity.scale = [0.7,0.7,0.7]
// or
cowAnchor.scale = SIMD3<Float>([1,1,1] * 0.7)

，您至少有两种方法可以沿任何轴（例如，沿Z轴）定位母牛模型：

cowEntity.position = SIMD3<Float>(0,-2)
// or
cowAnchor.position.z = -2.0

因此，如您所见，在转换cowAnchor时，其所有子代也将进行此转换。

第二步

您需要在3D创作应用程序中适当放置模型的pivot point。目前，RealityKit还没有像simdPivot实例属性在SceneKit中那样可以固定轴心位置的工具。