SCNNode childNodes的总高度 [英] Total height of SCNNode childNodes

问题描述

我目前正在使用以下内容获取 SCNNode 中所有子节点的总高度。是否有更高效/更好/更短/更快速的方式来做到这一点？

I'm currently using the following to get the total height of all of the child nodes in a SCNNode. Is there a more efficient/better/shorter/more swift-like way to do this?

CGFloat(columnNode.childNodes.reduce(CGFloat()) {
    let geometry = $1.geometry! as SCNBox
    return $0 + geometry.height
})

推荐答案

是的，这也是一种能让你得到更正确答案的方法。求和所有子节点几何的高度...

Yes, and a way that'll get you a more correct answer, too. Summing the height of all the child nodes' geometries...

• 仅在几何为 SCNBox <时才有效/ code>


• 不考虑子节点的变换（如果它们被移动，旋转或缩放会怎样？）


• 不考虑父节点的变换（如果你想在场景空间中高度怎么办？）

你想要的是< a href =https://developer.apple.com/reference/scenekit/scnboundingvolume =nofollow> SCNBoundingVolume 协议，适用于所有节点和几何，并描述包含所有节点（及其子节点）内容的最小矩形或球形空间。

What you want is the SCNBoundingVolume protocol, which applies to all nodes and geometries, and describes the smallest rectangular or spherical space containing all of a node's (and its subnodes') content.

在Swift 3中，这非常简单：

In Swift 3, this is super easy:

let (min, max) = columnNode.boundingBox

此后， min 和 max 是较低的坐标 - 最小的po的左前角和右上角包含 columnNode 内所有内容的ssible框，无论内容是如何排列的（以及涉及的几何类型）。这些坐标在与 columnNode.position 相同的系统中表示，因此如果您要查找的高度位于该空间的y轴方向，则只需减去这两个向量的y坐标：

After this, min and max are the coordinates of the lower-rear-left and upper-front-right corners of the smallest possible box containing everything inside columnNode, no matter how that content is arranged (and what kind of geometry is involved). These coordinates are expressed in the same system as columnNode.position, so if the "height" you're looking for is in the y-axis direction of that space, just subtract the y-coordinates of those two vectors:

let height = max.y - min.y

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在Swift 2中，它的语法有点奇怪，但效果很好够了：

---

In Swift 2, the syntax for it is a little weird, but it works well enough:

var min = SCNVector3Zero
var max = SCNVector3Zero
columnNode.getBoundingBoxMin(&min, max: &max)

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