SceneKit - SCNText 居中不正确 [英] SceneKit - SCNText centering incorrectly

问题描述

我尝试在下面的代码中将文本字符串 (SCNText) 放入一个框 (SCNBox) 内.框的大小看起来正确，但文本不在框的右中心.任何想法或解决方案?谢谢

I have tried to make a text string (SCNText) fit inside a box (SCNBox) in the code below. The size of the box looks correct but the text is not in the right center of the box. Any idea or solution? Thanks

let geoText = SCNText(string: "Hello", extrusionDepth: 1.0)
geoText.font = UIFont (name: "Arial", size: 8)
geoText.firstMaterial!.diffuse.contents = UIColor.red
let textNode = SCNNode(geometry: geoText)

let (minVec, maxVec) = textNode.boundingBox
scnScene.rootNode.addChildNode(textNode)

let w = CGFloat(maxVec.x - minVec.x)
let h = CGFloat(maxVec.y - minVec.y)
let d = CGFloat(maxVec.z - minVec.z)

let geoBox = SCNBox(width: w, height: h, length: d, chamferRadius: 0)
geoBox.firstMaterial!.diffuse.contents = UIColor.green.withAlphaComponent(0.5)
scnScene.rootNode.addChildNode(boxNode)

已我仅添加了带有 debugOptions showBoundingBoxes 的字符串的新图像(无 SCNBox 节点)以查看其边界框

Edited: I have added a new image of the string only (no SCNBox node) with debugOptions showBoundingBoxes to see its bounding box

解决方案 1:

根据 vdugnist 的回答，我为任何想要测试的人创建了一个游乐场代码:

From vdugnist's answer, I create a playground code for anyone who wants to test:

import UIKit
import SceneKit
import PlaygroundSupport

var sceneView = SCNView(frame: CGRect(x: 0, y: 0, width: 600, height: 600))
var scene = SCNScene()
sceneView.scene = scene
PlaygroundPage.current.liveView = sceneView

let geoText = SCNText(string: "Hello", extrusionDepth: 1.0)
geoText.font = UIFont (name: "Arial", size: 12)
geoText.firstMaterial!.diffuse.contents = UIColor.red
let textNode = SCNNode(geometry: geoText)

let (minVec, maxVec) = textNode.boundingBox
textNode.position = SCNVector3(x: (minVec.x - maxVec.x) / 2, y: minVec.y - maxVec.y, z: 0)
textNode.pivot = SCNMatrix4MakeTranslation((maxVec.x - minVec.x) / 2, 0, 0)
scene.rootNode.addChildNode(textNode)

let w = CGFloat(maxVec.x - minVec.x)
let h = CGFloat(maxVec.y - minVec.y)
let d = CGFloat(maxVec.z - minVec.z)

let geoBox = SCNBox(width: w, height: h, length: d, chamferRadius: 0)
geoBox.firstMaterial!.diffuse.contents =   UIColor.green.withAlphaComponent(0.5)
let boxNode = SCNNode(geometry: geoBox)
boxNode.position = SCNVector3Make((maxVec.x - minVec.x) / 2 + minVec.x, (maxVec.y - minVec.y) / 2 + minVec.y, 0);
textNode.addChildNode(boxNode)

解决方案 2:

我需要将文本移动到位置零 (0, 0, 0) 而不是同时移动文本和周围框，因此我继续更改解决方案 1 中文本的枢轴.现在代码如下:

I need to move the text to position zero (0, 0, 0) instead of moving both text and the around box, thus I continue to change the pivot of the text from Solution 1. Now the code is as the following:

import UIKit
import SceneKit
import PlaygroundSupport


var sceneView = SCNView(frame: CGRect(x: 0, y: 0, width: 600, height: 600))
var scene = SCNScene()
sceneView.scene = scene
PlaygroundPage.current.liveView = sceneView


let geoText = SCNText(string: "Hello", extrusionDepth: 1.0)
geoText.font = UIFont (name: "Arial", size: 12)
geoText.firstMaterial!.diffuse.contents = UIColor.red
let textNode = SCNNode(geometry: geoText)

let (minVec, maxVec) = textNode.boundingBox
textNode.pivot = SCNMatrix4MakeTranslation((maxVec.x - minVec.x) / 2 + minVec.x, (maxVec.y - minVec.y) / 2 + minVec.y, 0)
scene.rootNode.addChildNode(textNode)

let w = CGFloat(maxVec.x - minVec.x)
let h = CGFloat(maxVec.y - minVec.y)
let d = CGFloat(maxVec.z - minVec.z)

let geoBox = SCNBox(width: w, height: h, length: d, chamferRadius: 0)
geoBox.firstMaterial!.diffuse.contents = UIColor.green.withAlphaComponent(0.6)
let boxNode = SCNNode(geometry: geoBox)
scene.rootNode.addChildNode(boxNode)

推荐答案

SCNText 与其他几何图形的不同之处在于 SCNText 原点位于左下角.在其他几何图形中，它是底部中心.

The difference of SCNText from other geometries is that SCNText origin point positioned at bottom left corner. In other geometries, it is a bottom center.

要修复父节点中的文本位置，您可以将其 pivotPoint.x 设置为宽度的一半:

To fix text position in parent node you can set its pivotPoint.x to half of width:

SCNVector3 min, max;
[textNode getBoundingBoxMin:&min max:&max];
textNode.pivot = SCNMatrix4MakeTranslation((max.x - min.x) / 2, 0, 0);

要固定子节点的位置，您应该将它们的位置设置为宽度的一半加上最小:

To fix subnodes position, you should set their position to half of width plus min:

SCNVector3 min, max;
[textNode getBoundingBoxMin:&min max:&max];
subnode.position = SCNVector3Make((max.x - min.x) / 2 + min.x, (max.y - min.y) / 2 + min.y, 0);

这篇关于SceneKit - SCNText 居中不正确的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！