SCNNode 初始化大小

初始化模型,位置为 SCNVector3(0, -1, -2), 对于大的模型, 初始化后不容易被用户找到, 所以初始化时让模型全貌的显示在屏幕前方

1lazy var node: AudioinARKitLocationNode = {
2    
3    let modelScene = SCNScene(named: scnName)!
4    let cup = modelScene.rootNode.childNodes[0]
5    let node = AudioinARKitLocationNode(location: location, node: cup)
6    node.name = scnName
7    let boundingBox = node.boundingBox
8    let distance = boundingBox.max.distance(to: boundingBox.min)
9    let base: Float = 0.8
10    if distance > base {
11        // 缩放模型, 初始化时,不超出屏幕大小
12        let scale = base / distance
13        node.scale = SCNVector3(scale, scale, scale)
14    }
15    return node
16    
17}()
18extension SCNVector3 {
19    func distance(to anotherVector: SCNVector3) -> Float {
20        return sqrt(pow(anotherVector.x - x, 2) + pow(anotherVector.z - z, 2))
21    }    
22}