swift - 如何在 Swift 中以编程方式旋转 USDZ 文件中的 3D 模型？

Question

我的应用目前正在检测一张明信片图片。检测到后，我将狗的 3D 模型放在它上面。问题是，该模型目前让狗的背部坐在卡片上，而不是它的脚。

有没有办法以编程方式旋转模型，使脚站在明信片上？

class ViewController: UIViewController, ARSCNViewDelegate {
    
    @IBOutlet var sceneView: ARSCNView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        sceneView.delegate = self
    }
    
//MARK-: WHERE I CONFIGURE MY APP TO DETECT AN IMAGE

    override func viewWillAppear(_ animated: Bool) {
            super.viewWillAppear(animated)
            
            let configuration = ARImageTrackingConfiguration()
            
            guard let trackedImages = ARReferenceImage.referenceImages(inGroupNamed: "Photos", bundle: Bundle.main) else {
                print("No images available")
                return
            }
            
            configuration.trackingImages = trackedImages
            configuration.maximumNumberOfTrackedImages = 7
            
            sceneView.session.run(configuration)
    }
    
//MARK-: WHERE I PLACE A PLANE/DOG MODEL (named: shipScene) OVER THE DETECTED IMAGE

     func renderer(_ renderer: SCNSceneRenderer, nodeFor anchor: ARAnchor) -> SCNNode? {
            
            let node = SCNNode()
            
            if let imageAnchor = anchor as? ARImageAnchor {
                let plane = SCNPlane(width: imageAnchor.referenceImage.physicalSize.width, height: imageAnchor.referenceImage.physicalSize.height)

                plane.firstMaterial?.diffuse.contents = UIColor(white: 1, alpha: 0.8)

                let planeNode = SCNNode(geometry: plane)
                planeNode.eulerAngles.x = -.pi / 2

                guard let url = Bundle.main.url(forResource: "shipScene", withExtension: "usdz") else { fatalError() }
                let mdlAsset = MDLAsset(url: url)
                let dogScene = SCNScene(mdlAsset: mdlAsset)
                let dogNode = shipScene.rootNode.childNodes.first!

                shipNode.position = SCNVector3Zero
                shipNode.position.z = 0.15
                
                planeNode.addChildNode(shipNode)
                node.addChildNode(planeNode)
            }
            
            return node
    }
    
}

我想我可以使用一个演绎版

shipNode.position.x

移动模型，但任何尝试都只是移动模型(而不是旋转它)。

Answer 1

首先，您必须从场景中检索模型节点。请注意节点名称与场景名称不同!您可以在 Scene graph 层次结构中找到您的节点。

let model = scene.rootNode.childNode(withName: "myModel", recursively: true)!

然后您可以使用 rotation 属性旋转它:

model.rotation.y = -CGFloat.pi / 2

或使用 eulerAngles 属性:

model.eulerAngles = SCNVector3(0, -CGFloat.pi/2, 0)

或使用orientation属性:

model.orientation = SCNVector4(0, 1, 0, -CGFloat.pi/2)

注意节点的枢轴点 在哪里。旋转应该围绕枢轴点。