Ios SceneKit沿路径设置节点动画

我有一个盒子节点

_boxNode = [SCNNode node];
_boxNode.geometry = [SCNBox boxWithWidth:1 height:1 length:1 chamferRadius:0];
_boxNode.position = SCNVector3Make(0, 0, -2);
[scene.rootNode addChildNode:_boxNode];

我有一条路

CGPathRef path = CGPathCreateWithEllipseInRect(CGRectMake(-2, -2, 4, 4), nil);

我想让我的箱子沿着我的路径旅行一次

如何在SceneKit中执行此操作

我想做一个方法

[_boxNode runAction:[SCNAction moveAlongPath:path forDuration:duration]];

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我也遇到了这个问题，我写了一个小游戏。动画效果很好。有一件事需要做。必须计算每个点之间的距离，以便缩放时间以获得平滑动画。只要把代码复制粘贴到操场上就行了。代码是Swift 3

这是我的解决方案（BezierPath扩展不是我的，在这里找到的）：

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是什么阻止你进行搜索？我以前看过类似的主题。我以前用过一个动画。SceneKit没有内置的API来沿路径移动。我的作品体积庞大，最多也过于复杂。所以我想知道是否有人有一个简单的解决方案。将CoreAnimation动画添加到节点不起作用吗？Scenekit确实需要对样条线的支持。。。手工操作的一种方法是在3D软件中构建路径，然后自己在点之间插入位置。我通常就是这样做的。看看这个答案。希望它能有所帮助：

import UIKit
import SceneKit
import PlaygroundSupport

let animationDuration = 0.1

public extension UIBezierPath {

    var elements: [PathElement] {
        var pathElements = [PathElement]()
        withUnsafeMutablePointer(to: &pathElements) { elementsPointer in
            cgPath.apply(info: elementsPointer) { (userInfo, nextElementPointer) in
                let nextElement = PathElement(element: nextElementPointer.pointee)
                let elementsPointer = userInfo!.assumingMemoryBound(to: [PathElement].self)
                elementsPointer.pointee.append(nextElement)
            }
        }
        return pathElements
    }
}

public enum PathElement {

    case moveToPoint(CGPoint)
    case addLineToPoint(CGPoint)
    case addQuadCurveToPoint(CGPoint, CGPoint)
    case addCurveToPoint(CGPoint, CGPoint, CGPoint)
    case closeSubpath

    init(element: CGPathElement) {
        switch element.type {
        case .moveToPoint: self = .moveToPoint(element.points[0])
        case .addLineToPoint: self = .addLineToPoint(element.points[0])
        case .addQuadCurveToPoint: self = .addQuadCurveToPoint(element.points[0], element.points[1])
        case .addCurveToPoint: self = .addCurveToPoint(element.points[0], element.points[1], element.points[2])
        case .closeSubpath: self = .closeSubpath
        }
    }
}

public extension SCNAction {

    class func moveAlong(path: UIBezierPath) -> SCNAction {

        let points = path.elements
        var actions = [SCNAction]()

        for point in points {

            switch point {
            case .moveToPoint(let a):
                let moveAction = SCNAction.move(to: SCNVector3(a.x, a.y, 0), duration: animationDuration)
                actions.append(moveAction)
                break

            case .addCurveToPoint(let a, let b, let c):
                let moveAction1 = SCNAction.move(to: SCNVector3(a.x, a.y, 0), duration: animationDuration)
                let moveAction2 = SCNAction.move(to: SCNVector3(b.x, b.y, 0), duration: animationDuration)
                let moveAction3 = SCNAction.move(to: SCNVector3(c.x, c.y, 0), duration: animationDuration)
                actions.append(moveAction1)
                actions.append(moveAction2)
                actions.append(moveAction3)
                break

            case .addLineToPoint(let a):
                let moveAction = SCNAction.move(to: SCNVector3(a.x, a.y, 0), duration: animationDuration)
                actions.append(moveAction)
                break

            case .addQuadCurveToPoint(let a, let b):
                let moveAction1 = SCNAction.move(to: SCNVector3(a.x, a.y, 0), duration: animationDuration)
                let moveAction2 = SCNAction.move(to: SCNVector3(b.x, b.y, 0), duration: animationDuration)
                actions.append(moveAction1)
                actions.append(moveAction2)
                break

            default:
                let moveAction = SCNAction.move(to: SCNVector3(0, 0, 0), duration: animationDuration)
                actions.append(moveAction)
                break
            }   
        }
        return SCNAction.sequence(actions)
    }
}



let scnView = SCNView(frame: CGRect(x: 0, y: 0, width: 500, height: 500))
scnView.autoenablesDefaultLighting = true

let scene = SCNScene()
scnView.scene = scene

let light = SCNLight()
light.type = .ambient
let lightNode = SCNNode()
lightNode.light = light
scene.rootNode.addChildNode(lightNode)

let camera = SCNCamera()
let cameraNode = SCNNode()
cameraNode.camera = camera
cameraNode.position = SCNVector3(0,0,10)
scene.rootNode.addChildNode(cameraNode)

let box = SCNBox(width: 1, height: 1, length: 1, chamferRadius: 0)
let boxNode = SCNNode(geometry: box)
boxNode.geometry?.firstMaterial?.diffuse.contents = UIColor.red

scene.rootNode.addChildNode(boxNode)

let path1 = UIBezierPath(roundedRect: CGRect(x: 1, y: 1, width: 2, height: 2), cornerRadius: 1)

let moveAction = SCNAction.moveAlong(path: path1)
let repeatAction = SCNAction.repeatForever(moveAction)
SCNTransaction.begin()
SCNTransaction.animationDuration = Double(path1.elements.count) * animationDuration
boxNode.runAction(repeatAction)
SCNTransaction.commit()

PlaygroundPage.current.liveView = scnView