从Bezier路径计算点 [英] Compute points from Bezier Path

问题描述

假设我有一个随机的贝塞尔曲线，如下所示:

Let's say I have a random bezier path, like this:

let bezierPath = UIBezierPath()
bezierPath.move(to: CGPoint(x: 3, y: 0.84))
bezierPath.addCurve(to: CGPoint(x: 11, y: 8.84), controlPoint1: CGPoint(x: 3, y: 1.84), controlPoint2: CGPoint(x: 9, y: 4.59))
// [...]
bezierPath.addCurve(to: CGPoint(x: 3, y: 0.84), controlPoint1: CGPoint(x: 7, y: 4.84), controlPoint2: CGPoint(x: 3, y: -0.16))
bezierPath.close()

我想创建一个为给定百分比计算CGPoint的函数，其中bezierPath的第一个点为0％，最后一个点为100％:

I would like to create a function that compute a CGPoint for a given percentage, where 0% is the first point and 100% the last point of the bezierPath:

extension UIBezierPath {
    func getPointFor(percentage: Float) -> CGPoint {
        //Computation logic
        return result
    }
}

我发现了此帖子但是解决方案不允许我获得所有点(例如，位于路径的15.5％处).

I have found this post but the solution doesn't allow me to get all points (position at 15.5% of the path for example).

有没有办法做到这一点?

Is there a way to do this?

推荐答案

我找到了用Objective-C编写的解决方案.您可以在此处找到源代码.

I have found a solution written in objective-c. You can find the source code here.

我通过使用桥接来设法使用它标头:

#ifndef bridging_header_h
#define bridging_header_h

#import "UIBezierPath+Length.h"

#endif /* bridge_header_h */

您可以使用以下两个功能:

And you can use the two functions like this:

print("length=\(bezierPath.length())")
for i in 0...100 {
    let percent:CGFloat = CGFloat(i) / 100.0
    print("point at [\(percent)]=\(bezierPath.point(atPercentOfLength: percent))")
}

输出:

length=143.316117804497
point at [0.0]=(3.0, 0.839999973773956)
point at [0.01]=(3.26246070861816, 1.29733419418335)
point at [0.02]=(3.97137236595154, 1.91627132892609)
point at [0.03]=(5.00902938842773, 2.69386911392212)
[...]
point at [0.99]=(3.27210903167725, 0.765813827514648)
point at [1.0]=(3.0, 0.839999973773956)

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