ios - Sprite Kit 背景滚动垂直

Question

我想创建一个垂直移动的滚动背景。因为我想随时停止后台，所以我不希望它在 Update: 函数中实现。

在我的代码中，背景垂直滚动，但仍然不完美。有时它会随机弹出，或者让整个场景降低 FPS。

更新 1:

正如 Christian 所说，我现在使用 Update 函数，但使用 Bool 来确定它是否应该停止。如您所见，我加快了 Scene 的速度，但 Background 移动的速度不会改变。我怎样才能更快地启动后台？

代码:

  ...
  var Scroll:Bool!
  ...
  self.runAction(SKAction.speedBy(2.0, duration: 25))
  ...

  func addBackground(){

    Background1 = SKSpriteNode(imageNamed: "Background.png")
    Background1.size = CGSize(width: self.frame.size.width, height: self.frame.size.height)
    Background1.position = CGPoint(x: self.frame.size.width / 2, y: self.frame.size.height / 2)
    Background1.zPosition = 1
    self.addChild(Background1)

    Background2 = SKSpriteNode(imageNamed: "Background.png")
    Background2.size = CGSize(width: self.frame.size.width, height: self.frame.size.height)
    Background2.position = CGPoint(x: self.frame.size.width / 2, y: Background1.position.y - Background2.size.height)
    Background2.zPosition = 1
    self.addChild(Background2)

}

override func update(currentTime: CFTimeInterval) {
    /* Called before each frame is rendered */

    if (Scroll == true){

    Background1.position = CGPointMake(Background1.position.x, Background1.position.y + 4)
    Background2.position = CGPointMake(Background2.position.x, Background2.position.y + 4)

    if(Background1.position.y > self.frame.size.height + (Background1.size.height / 2))
    {
        Background1.position = CGPointMake(self.frame.size.width / 2, Background2.position.y - Background1.size.height)
    }

    if(Background2.position.y > self.frame.size.height + (Background2.size.height / 2))
    {
        Background2.position = CGPointMake(self.frame.size.width / 2, Background1.position.y - Background2.size.height)

    }

    }
}

Answer 1

你应该把它放在 update 方法中。您可以使用 bool 值来停止更新过程。例如:

var moveBackground = true

func stopBackgroundMovement(){
    moveBackground = false
}

//In your update-method:
if moveBackground {
    //move the background
    Background.position.y += 1
}

如果你想每 x 秒调用一次更新函数，你可以使用更新方法中的 NSTimeInterval 参数。