ios - SceneKit 子节点位置在父节点旋转期间未更改

Question

我正在尝试在 SceneKit 中重新编码相机管理。为此，我使用 UIPanGestureRecognizer 使相机围绕物体旋转(在本例中围绕场景中心)。

接下来，我得到不同的比率或长度，以确定要在连接相机的假想球体(代码中的 cameraOrbit)的轴(X、Y、Z)处添加的角度。

我的问题是我使用相机的位置来确定要添加到球体的角度。但地位是不变的。当我改变球体旋转时，子节点相机的位置永远不会更新。然后角度永远不会改变。

import SceneKit
import UIKit

class SceneManager
{
    private let scene: SCNScene
    private let view: SCNView
    private let camera: SCNNode
    private let cameraOrbit: SCNNode
    private let cameraRadius: Float

    init(view: SCNView, assetFolder: String, sceneName: String, cameraName: String, backgroundColor: UIColor) {
        self.view = view
        self.scene = SCNScene(named: (assetFolder + "/" + sceneName))!
        if (self.scene.rootNode.childNodeWithName(cameraName, recursively: true) == nil) {
            print("Fatal error: Cannot find camera in scene with name :\"", cameraName, "\"")
            exit(1)
        }
        self.camera = self.scene.rootNode.childNodeWithName(cameraName, recursively: true)! // Retrieve cameraNode created in scene file
        self.cameraOrbit = SCNNode()
        self.cameraOrbit.addChildNode(self.camera)
        self.cameraRadius = sqrt(pow((self.camera.position.x), 2) + pow(self.camera.position.y, 2)) // CameraOrbit radius for rotation camera in panHandler
        self.scene.rootNode.addChildNode(self.cameraOrbit)
        let panGesture = UIPanGestureRecognizer(target: self, action: #selector(panHandler(_:)))
        panGesture.maximumNumberOfTouches = 1
        self.view.addGestureRecognizer(panGesture)
        self.view.backgroundColor = backgroundColor
        self.view.pointOfView = self.camera
        self.view.scene = self.scene
    }

    @objc private func panHandler(sender: UIPanGestureRecognizer) {
        let alpha = cos(self.camera.position.z / self.cameraRadius) // Get angle of camera

        // --
        print(self.camera.position) // <-------- (X, Y, Z) The axes position are always the same
        // --

        var ratioX = 1 - ((CGFloat)(alpha) / (CGFloat)(M_PI)) // Get the radio with angle for apply to Z and X axes rotation
        var ratioZ = ((CGFloat)(alpha) / (CGFloat)(M_PI))
        // Change direction of rotation depending camera's position in trigonometric circle
        if (self.camera.position.z > 0 && self.camera.position.x < 0) {
            ratioZ *= -1
        } else if (self.camera.position.z < 0 && self.camera.position.x < 0) {
            ratioX *= -1
            ratioZ *= -1
        } else if (self.camera.position.z > 0 && self.camera.position.x > 0) {
            ratioX *= -1
        }
        // Set the angle rotation to add at imaginary sphere (cameraOrbit)
        let xAngleToAdd = (sender.velocityInView(sender.view!).y / 10000) * ratioX
        let yAngleToAdd = (sender.velocityInView(sender.view!).x / 10000) * (-1)
        let zAngleToAdd = (sender.velocityInView(sender.view!).y / 10000) * ratioZ
        let rotation = SCNAction.rotateByX(xAngleToAdd, y: yAngleToAdd, z: zAngleToAdd, duration: 0.5)
        self.cameraOrbit.runAction(rotation)
    }
}

如果有人有想法？谢谢

Answer 1

当您更新父节点的变换(位置、旋转、缩放)时，子节点的变换在局部坐标(相对于父节点)中保持不变，它仅在世界坐标中发生变化。

如果您想访问给定节点的世界变换，请使用 worldTransform属性(property)。