使用 CGMutablePath 创建路径会创建到错误 CGPoint 的行 [英] Creating path using CGMutablePath creates line to wrong CGPoint

问题描述

我打算用二维箭头在屏幕上显示 AR 对象的信息.所以我使用 projectPoint 来获取屏幕中对象的相应位置.我有这个函数可以返回将节点的 3D 位置转换为 2D 和 CGPoint 以显示信息文本.

I was planning to display information of AR object in screen with arrow in 2D. So I used projectPoint to get corresponding position of object in screen. I have this function to return convert 3D position of node to 2D and CGPoint to display info text in.

func getPoint(sceneView: ARSCNView) -> (CGPoint, CGPoint){
    let projectedPoint = sceneView.projectPoint(node.worldPosition)
    return (point, CGPoint(x: CGFloat(projectedPoint.x), y: CGFloat(projectedPoint.y)) )
}

这是使用 SpriteKit 画线:

let (f,s) = parts[3].getPoint(sceneView: sceneView) 
line.removeFromParent()
let path = CGMutablePath()
path.move(to: f)
path.addLine(to: s)
line = SKShapeNode(path: path)
spriteScene.addChild(line)

这就是我得到的

我期望在节点(蓝色网格)中修复另一端的行.
我缺少什么吗?还是 projectPoint 以其他方式工作?

What I expect is another end of line to be fixed in node (blue mesh).
Is there something I am missing? Or does projectPoint works some other way?

edit:似乎 projectPoint 正在返回正确的值，但是在创建路径时 path.addLine(to: s) 这个点正在移动到不同的位置.

edit: It seems projectPoint is returning correct value but while creating path path.addLine(to: s) this point is shifting to different position.

推荐答案

path.addLine(to: s) s 这里的 y 已经颠倒了，所以这样做了

path.addLine(to: s) s here had reversed y so this did the trick

let frame = self.sceneView.frame
let sInversed = CGPoint(x: from.x, y: frame.height - s.y)

path.addLine(to: sInversed)

SKScene 的来源在屏幕的左下角而不是左上角.

Here origin of SKScene was in bottom left of screen instead of top left.

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