如何找到两个CG点之间的距离？

Question

当我们在UIScrollView中用两个手指进行多点触控时,我们得到两个CG点.我想找到它们之间的距离.然后我们再次进行捏(内部或外部),然后我们将再次得到两个点.然后在找到这两点之间的距离之后,我想决定是否捏入或捏出.如果我已经收入,肯定新的距离会更小,反之亦然.

但是不知道如何找到2点之间距离的准确测量值来进行比较？有人对此有所了解吗？

Answer 1

您可以使用hypot()或hypotf()函数来计算斜边.给出两点p1并且p2:

CGFloat distance = hypotf(p1.x - p2.x, p1.y - p2.y);

就是这样.

Answer 2

p1和之间的距离p2:

CGFloat xDist = (p2.x - p1.x);
CGFloat yDist = (p2.y - p1.y);
CGFloat distance = sqrt(xDist * xDist + yDist * yDist);

放入一个功能:

func distance(_ a: CGPoint, _ b: CGPoint) -> CGFloat {
    let xDist = a.x - b.x
    let yDist = a.y - b.y
    return CGFloat(sqrt(xDist * xDist + yDist * yDist))
}

背景:毕达哥拉斯定理

如果您只需要计算点之间的距离是增加还是减少,您可以省略sqrt(),这会使它更快一些.

Answer 3

对于快速用户

extension CGPoint {
    func distance(to point: CGPoint) -> CGFloat {
        return sqrt(pow(x - point.x, 2) + pow(y - point.y, 2))
    }
}

Answer 4

使用Swift 4,您可以选择以下5个Playground代码中的一个,以获得两个CGPoint实例之间的距离.

1.使用达尔文sqrt(_:)功能

import CoreGraphics

func distance(from lhs: CGPoint, to rhs: CGPoint) -> CGFloat {
    let xDistance = lhs.x - rhs.x
    let yDistance = lhs.y - rhs.y
    return sqrt(xDistance * xDistance + yDistance * yDistance)
}

let point1 = CGPoint(x: -10, y: -100)
let point2 = CGPoint(x: 30, y: 600)

distance(from: point1, to: point2) // 701.141925718324

2.使用CGFloat squareRoot()方法

import CoreGraphics

func distance(from lhs: CGPoint, to rhs: CGPoint) -> CGFloat {
    let xDistance = lhs.x - rhs.x
    let yDistance = lhs.y - rhs.y
    return (xDistance * xDistance + yDistance * yDistance).squareRoot()
}

let point1 = CGPoint(x: -10, y: -100)
let point2 = CGPoint(x: 30, y: 600)

distance(from: point1, to: point2) // 701.141925718324

3.使用CGFloat squareRoot()方法和核心图形pow(_:_:)功能

import CoreGraphics

func distance(from lhs: CGPoint, to rhs: CGPoint) -> CGFloat {
    return (pow(lhs.x - rhs.x, 2) + pow(lhs.y - rhs.y, 2)).squareRoot()
}

let point1 = CGPoint(x: -10, y: -100)
let point2 = CGPoint(x: 30, y: 600)

distance(from: point1, to: point2) // 701.141925718324

4.使用核心图形hypot(_:_:)功能

import CoreGraphics

func distance(from lhs: CGPoint, to rhs: CGPoint) -> CGFloat {
    return hypot(lhs.x - rhs.x, lhs.y - rhs.y)
}

let point1 = CGPoint(x: -10, y: -100)
let point2 = CGPoint(x: 30, y: 600)

distance(from: point1, to: point2) // 701.141925718324

5.使用Core Graphics hypot(_:_:)功能和CGFloat distance(to:)方法

import CoreGraphics

func distance(from lhs: CGPoint, to rhs: CGPoint) -> CGFloat {
    return hypot(lhs.x.distance(to: rhs.x), lhs.y.distance(to: rhs.y))
}

let point1 = CGPoint(x: -10, y: -100)
let point2 = CGPoint(x: 30, y: 600)

distance(from: point1, to: point2) // 701.141925718324

Answer 5

-(float)distanceFrom:(CGPoint)point1 to:(CGPoint)point2
{
CGFloat xDist = (point2.x - point1.x);
CGFloat yDist = (point2.y - point1.y);
return sqrt((xDist * xDist) + (yDist * yDist));
}

如果您使用的是cocos2d

float distance = ccpDistance(point1, point2);