计算圆弧边缘上两点之间的角度Swift SpriteKit [英] calculating angle between two points on edge of circle Swift SpriteKit

问题描述

在Swift中如何计算圆弧边缘上两个点之间的度。

How would you calculate the degrees between two points on the edge of a circle in Swift.

推荐答案

给出点 p1 ， p2 在中心为 center ，
的圆上，您需要计算先求差向量：

Given points p1, p2 on a circle with center center, you would compute the difference vectors first:

let v1 = CGVector(dx: p1.x - center.x, dy: p1.y - center.y)
let v2 = CGVector(dx: p2.x - center.x, dy: p2.y - center.y)

然后

let angle = atan2(v2.dy, v2.dx) - atan2(v1.dy, v1.dx)

是这些向量之间的（弧度）弧度，并且

is the (directed) angle between those vectors in radians, and

var deg = angle * CGFloat(180.0 / M_PI)

角度（度）。计算值的范围可以是-360 .. 360，因此您
可能希望将其规格化为0 <== deg <

the angle in degrees. The computed value can be in the range -360 .. 360, so you might want to normalize it to the range 0 <= deg < 360 with

if deg < 0 { deg += 360.0 }

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