如何减小每个圆象限的大小以产生间隙

Question

下面是我的圈子象限的图像，后面是代码。如何减少每个弧线，每边10个点/像素，以便弧线之间有间隙？起初我在每侧减少它们this.$messages = [];但是左边没有产生直线间隙，而是一部分刚刚切掉，这不是我想要的。我需要每个弧都有直边（水平和垂直）而不是对角线。

CGFloat(Double.pi/36)

Answer 1

下面是一些代码，当粘贴到iOS Playground时，会生成一张我认为符合您描述的图片。

为了使两侧与有间隙的地方的轴保持平行，你必须做一些数学计算才能弄清楚这些点是什么。然后，您必须绘制所需形状的轮廓，而不是依赖绘图系统添加的笔触宽度。如果您熟悉三角函数，数学并不太复杂，但您的问题表明您可能没问题。

import UIKit
import SpriteKit
import PlaygroundSupport

let radius = CGFloat(100)

let sceneSize = CGSize(width: 640, height: 480)
let sceneView = SKView(frame: CGRect(origin: CGPoint.zero, size: sceneSize))

let scene = SKScene(size: sceneSize)
scene.backgroundColor = UIColor.black

let topRightPath = arcSegment(center: CGPoint.zero, radius: radius, strokeWidth: 18, gapWidth: 18)

let topRightPathNode = SKShapeNode(path: topRightPath)
topRightPathNode.fillColor = SKColor.white
topRightPathNode.lineWidth = 0
topRightPathNode.position = CGPoint(x: 320, y: 240)
scene.addChild(topRightPathNode)


var reflectOnY = CGAffineTransform(scaleX: 1.0, y: -1.0)
let bottomRightPath = topRightPath.copy(using: &reflectOnY)!
let bottomRightPathNode = SKShapeNode(path: bottomRightPath)
bottomRightPathNode.fillColor = SKColor.orange
bottomRightPathNode.lineWidth = 0
bottomRightPathNode.position = CGPoint(x: 320, y: 240)
scene.addChild(bottomRightPathNode)


var reflectOnX = CGAffineTransform(scaleX: -1.0, y: 1.0)
let bottomLeftPath = bottomRightPath.copy(using: &reflectOnX)!
let bottomLeftPathNode = SKShapeNode(path: bottomLeftPath)
bottomLeftPathNode.fillColor = SKColor.green
bottomLeftPathNode.lineWidth = 0
bottomLeftPathNode.position = CGPoint(x: 320, y: 240)
scene.addChild(bottomLeftPathNode)


let topLeftPath = bottomLeftPath.copy(using: &reflectOnY)!
let topLeftPathNode = SKShapeNode(path: topLeftPath)
topLeftPathNode.fillColor = SKColor.blue
topLeftPathNode.lineWidth = 0
topLeftPathNode.position = CGPoint(x: 320, y:240)
scene.addChild(topLeftPathNode)

sceneView.presentScene(scene)

PlaygroundPage.current.liveView = sceneView
PlaygroundPage.current.needsIndefiniteExecution = true

func arcSegment(center : CGPoint,
                radius: CGFloat,
                strokeWidth: CGFloat,
                gapWidth: CGFloat) -> CGPath
{
    let halfStrokeWidth = strokeWidth / 2.0
    let outerRadius = radius + halfStrokeWidth
    let innerRadius = radius - halfStrokeWidth
    let halfGap = gapWidth / 2.0

    let outerStartAngle = CGFloat(atan2(sqrt(outerRadius * outerRadius - halfGap * halfGap), halfGap))
    let outerEndAngle = CGFloat(atan2(halfGap, sqrt(outerRadius * outerRadius - halfGap * halfGap)))

    let innerStartAngle = CGFloat(atan2(halfGap, sqrt(innerRadius * innerRadius - halfGap * halfGap)))
    let innerEndAngle = CGFloat(atan2(sqrt(innerRadius * innerRadius - halfGap * halfGap), halfGap))

    let path = CGMutablePath()

    path.addArc(center: center, radius: outerRadius, startAngle: outerStartAngle, endAngle: outerEndAngle, clockwise: true)
    // Quartz 2D will assume a "moveTo" here
    path.addArc(center: center, radius: innerRadius, startAngle: innerStartAngle, endAngle: innerEndAngle, clockwise: false)
    path.closeSubpath()


    return path
}