ios - SpriteKit/Swift-二进制运算符'>'不能应用于两个'CGVector'操作数

在我的游戏中，我需要比较碰撞时的两种速度。两种速度均为CGVector(dx:，dy :)格式。但是Swift 3不允许我使用'>'和'

func didBegin(_ contact: SKPhysicsContact) {
    var firstBody = SKPhysicsBody()
    var secondBody = SKPhysicsBody()
    let ballNode = self.childNode(withName: ballName)
    let defaultSpeedX:CGFloat = 100
    let defaultSpeedY:CGFloat = -100
    let maxSpeed = CGVector(dx: defaultSpeedX * 3, dy: defaultSpeedY * 3)
    let minSpeed = CGVector(dx: defaultSpeedX / 2 , dy: defaultSpeedY / 2)

    if contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask {
        firstBody = contact.bodyA
        secondBody = contact.bodyB
    } else {
        firstBody = contact.bodyB
        secondBody = contact.bodyA
    }

    if firstBody.categoryBitMask == ballBitmask && secondBody.categoryBitMask == drainBitmask {
        endGame()

    } else if firstBody.categoryBitMask == ballBitmask && secondBody.categoryBitMask == target1Bitmask {
        score += 20
        self.vc.scoreLabel.text = "Score: \(score)"
        let currentSpeedX = ballNode?.physicsBody?.velocity.dx
        let currentSpeedY = ballNode?.physicsBody?.velocity.dy
        let speedDouble = CGVector(dx: currentSpeedX! * 2, dy: currentSpeedY! * 2)

        if ballNode?.physicsBody?.velocity == maxSpeed {

            ballNode?.physicsBody?.velocity = maxSpeed

        } else if speedDouble < maxSpeed {

            ballNode?.physicsBody?.velocity = speedDouble

        } else if speedDouble > maxSpeed {

            ballNode?.physicsBody?.velocity = maxSpeed

        }

谢谢

最佳答案

向量的“速度”实际上是向量描述的三角形的斜边。试试这个:

extension CGVector {
    var speed: CGFloat {
        return hypot(dx, dy)
    }

    static func > (lhs: CGVector, rhs: CGVector) -> Bool {
        return lhs.speed > rhs.speed
    }

    static func < (lhs: CGVector, rhs: CGVector) -> Bool {
        return lhs.speed < rhs.speed
    }
}

let aaa = CGVector(dx: 10, dy: 10)
let bbb = CGVector(dx: 13, dy: 12)

print(aaa > bbb)

有了此扩展名后，您会发现现有代码} else if speedDouble < maxSpeed {将会编译。

它是如何工作的？嗯，作为矢量的速度由两个部分定义-水平速度dx和垂直速度dy。如果您将dx和dy想象为一个直角三角形的两侧，则向量的长度就是斜边(记住毕达哥拉斯)-这就是hypot返回的内容。

通过上面的扩展，<和>运算符现在可以比较CGVector对象的速度(您可以很高兴地重命名length)。