Swift-SKSpriteNode 速度不变

Question

根据此处帖子的说明； Swift-Making an SKNode simply "move forward" on an angle我写了这段代码，让一个角度随机化，并让我的 Sprite 在那个角度移动:

func setDegrees() {
    let ball1Degrees:UInt32 = arc4random_uniform(360)
    if ball1Degrees > 300 {
         ball2Degrees = Int(ball1Degrees) - 360
         ball3Degrees = Int(ball1Degrees) - 300
    }
    else if ball1Degrees > 240 {
         ball2Degrees = Int(ball1Degrees) + 60
         ball3Degrees = Int(ball1Degrees) - 360
    }
    else {
         ball2Degrees = Int(ball1Degrees) + 60
         ball3Degrees = Int(ball1Degrees) + 120
    }
}

func myFunction() {
    ball1.position = CGPoint(x: 0, y: 0)
    ball2.position = CGPoint(x: 0, y: 0)
    ball3.position = CGPoint(x: 0, y: 0)
    setDegrees()
    if ball1Degrees < 90 {
        ball1.physicsBody?.velocity = CGVector(dx: 1, dy: tan(Double(ball1Degrees) * (.pi / 180)))
    }
    if ball1Degrees == 90 {
        ball1.physicsBody?.velocity = CGVector(dx: 1, dy: 0)
    }
    if ball1Degrees > 90 && ball1Degrees <= 180 {
        ball1.physicsBody?.velocity = CGVector(dx: -1, dy: tan(Double(180 - ball1Degrees) * (.pi / 180)))
    }
    if ball1Degrees > 180 && ball1Degrees <= 270 {
        ball1.physicsBody?.velocity = CGVector(dx: -1, dy: -tan(Double(ball1Degrees - 180) * (.pi / 180)))
    }
    if ball1Degrees > 270 && ball1Degrees <= 0 {
        ball1.physicsBody?.velocity = CGVector(dx: 1, dy: -tan(Double(360 - ball1Degrees) * (.pi / 180)))
    }
    if ball2Degrees < 90 {
        ball2.physicsBody?.velocity = CGVector(dx: 1, dy: tan(Double(ball2Degrees) * (.pi / 180)))
    }
    if ball2Degrees == 90 {
        ball2.physicsBody?.velocity = CGVector(dx: 1, dy: 0)
    }
    if ball2Degrees > 90 && ball2Degrees <= 180 {
        ball2.physicsBody?.velocity = CGVector(dx: -1, dy: tan(Double(180 - ball2Degrees) * (.pi / 180)))
    }
    if ball2Degrees > 180 && ball2Degrees <= 270 {
        ball2.physicsBody?.velocity = CGVector(dx: -1, dy: -tan(Double(ball2Degrees - 180) * (.pi / 180)))
    }
    if ball2Degrees > 270 && ball2Degrees <= 0 {
        ball2.physicsBody?.velocity = CGVector(dx: 1, dy: -tan(Double(360 - ball2Degrees) * (.pi / 180)))
    }
    if ball3Degrees < 90 {
        ball3.physicsBody?.velocity = CGVector(dx: 1, dy: tan(Double(ball3Degrees) * (.pi / 180)))
    }
    if ball3Degrees == 90 {
        ball3.physicsBody?.velocity = CGVector(dx: 1, dy: 0)
    }
    if ball3Degrees > 90 && ball3Degrees <= 180 {
        ball3.physicsBody?.velocity = CGVector(dx: -1, dy: tan(Double(180 - ball3Degrees) * (.pi / 180)))
    }
    if ball3Degrees > 180 && ball3Degrees <= 270 {
        ball3.physicsBody?.velocity = CGVector(dx: -1, dy: -tan(Double(ball3Degrees - 180) * (.pi / 180)))
    }
    if ball3Degrees > 270 && ball3Degrees <= 0 {
        ball3.physicsBody?.velocity = CGVector(dx: 1, dy: -tan(Double(360 - ball3Degrees) * (.pi / 180)))
    } 

}

myFunction()

但是当我的游戏运行时，上面的速度变化似乎都没有被应用。重新定位到屏幕中心成功运行，甚至还有一些在这里不是特别相关的缩放 SKAction 命令，它们工作得很好。那么为什么速度没有变化呢？是不是我的计算机模拟器无法处理太多代码？还是我在某处犯了错误？如果有任何反馈，我将不胜感激。

提前致谢。

Answer 1

有几件事你做错了。但它们确实很容易修复。

首先，在我的另一个回答中，我提到了 dx : dy 的比率，而不是 dx 和 dy 的值。目前，您的节点速度非常慢，因此您看不出有什么不同。将 dx 和 dy 乘以 100:

ball1.physicsBody?.velocity = CGVector(dx: 100, dy: -tan(Double(360 - ball1Degrees) * (.pi / 180)) * 100)

另外，这个 if 语句不会被执行:

if ball1Degrees > 270 && ball1Degrees <= 0 {

我认为你应该尝试:

if ball1Degrees > 270 && ball1Degrees <= 360 {