Swift 游戏场景随着时间或分数改变背景？

Question

我的应用程序中有一个背景图像，它从上到下移动并重复。我希望在 x 时间后屏幕上显示不同的图像。

这样可以吗？

什么时候最好删除初始背景以避免层数过多？

    override func didMove(to view: SKView) {

    let bgTexture = SKTexture(imageNamed: "bg1.png")
    let moveBGanimation = SKAction.move(by: CGVector(dx: 0, dy: -bgTexture.size().height), duration: 4)
    let shiftBGAnimation = SKAction.move(by: CGVector(dx: 0, dy: bgTexture.size().height), duration: 0)
    let moveBGForever = SKAction.repeatForever(SKAction.sequence([moveBGanimation, shiftBGAnimation]))

    var i: CGFloat = 0

    while i < 3 {

        bg = SKSpriteNode(texture: bgTexture)
        bg.position = CGPoint(x: self.frame.midX, y: bgTexture.size().height * i)
        bg.size.width = self.frame.width
        bg.zPosition = -2

        bg.run(moveBGForever)
        self.addChild(bg)

        i += 1


    }

    bg2Timer = Timer.scheduledTimer(timeInterval: 3, target: self, selector: #selector(self.moveBG2), userInfo: nil, repeats: false)

}

func moveBG2() {

    let bg2Texture = SKTexture(imageNamed: "bg2.png")
    let moveBG2animation = SKAction.move(by: CGVector(dx: 0, dy: -bg2Texture.size().height * 2), duration: 8)
    let shiftBG2Animation = SKAction.move(by: CGVector(dx: 0, dy: bg2Texture.size().height), duration: 0)
    let moveBG2Forever = SKAction.repeatForever(SKAction.sequence([moveBG2animation, shiftBG2Animation]))

    var j: CGFloat = 0

    while j < 3 {

        bg2 = SKSpriteNode(texture: bg2Texture)
        bg2.position = CGPoint(x: self.frame.midX, y: bg2Texture.size().height + bg2Texture.size().height * j)
        bg2.size.width = self.frame.width
        bg2.zPosition = -1.5


        bg2.run(moveBG2Forever)
        self.addChild(bg2)

        j += 1


    }



}

Answer 1

这是我想出的一个主意。

重构这段代码：

let bgTexture = SKTexture(imageNamed: "bg.png")
    let moveBGanimation = SKAction.move(by: CGVector(dx: 0, dy: -bgTexture.size().height), duration: 4)
    let shiftBGAnimation = SKAction.move(by: CGVector(dx: 0, dy: bgTexture.size().height), duration: 0)
    let moveBGForever = SKAction.repeatForever(SKAction.sequence([moveBGanimation, shiftBGAnimation]))

方法：

func runBgActions(bgTextureName: String) {
    let bgTexture = SKTexture(imageNamed: bgTextureName)
    bg.texture = bgTexture
        let moveBGanimation = SKAction.move(by: CGVector(dx: 0, dy: -bgTexture.size().height), duration: 4)
        let shiftBGAnimation = SKAction.move(by: CGVector(dx: 0, dy: bgTexture.size().height), duration: 0)
        let moveBGForever = SKAction.repeatForever(SKAction.sequence([moveBGanimation, shiftBGAnimation]))
    bg.removeAllActions()
    bg.run(moveBGForever)
}

然后，创建另一个动作并运行它在不是 bg 的节点上，也许是场景本身。

let bg1Action = SKAction.run { runBgActions(bgTextureName: "bg1") }
let bg2Action = SKAction.run { runBgActions(bgTextureName: "bg2") }
let bg3Action = SKAction.run { runBgActions(bgTextureName: "bg3") }
let waitAction = SKAction.wait(forDuration: 10)
let sequence = SKAction.sequence([bg1Action, waitAction, bg2Action, waitAction, bg3Action, waitAction])
let repeatForeverAction = SKAction.repeatForever(sequence)
self.run(repeatForeverAction) // assuming self is the scene here

另一种方法是使用 SKAction.group 同时执行等待和移动后台操作，但我发现实现起来非常违反直觉。

在看到你的代码后，这就是我能够想出的：

var bg = SKSpriteNode()

func runBgActions(bgTextureName: String) {
    let bgTexture = SKTexture(imageNamed: bgTextureName)
    bg.texture = bgTexture
    bg.position = CGPoint(x: self.frame.minX, y: self.frame.minY)
    let moveBGanimation = SKAction.move(by: CGVector(dx: 0, dy: -(bgTexture.size().height - self.frame.height)), duration: 4)
    let shiftBGAnimation = SKAction.move(by: CGVector(dx: 0, dy: bgTexture.size().height - self.frame.height), duration: 0)
    let moveBGForever = SKAction.repeatForever(SKAction.sequence([moveBGanimation, shiftBGAnimation]))
    bg.removeAllActions()
    bg.run(moveBGForever)
}

override func didMove(to view: SKView) {
    var i: CGFloat = 0

    bg = SKSpriteNode(imageNamed: "bg1") // replace this with your first background's texture name
    bg.position = CGPoint(x: self.frame.minX, y: self.frame.minY)
    bg.anchorPoint = CGPoint(x: 0, y: 0)
    bg.size.width = self.frame.width
    bg.zPosition = -2
    self.addChild(bg)

    i += 1
    let bg1Action = SKAction.run { self.runBgActions(bgTextureName: "bg1") }
    let bg2Action = SKAction.run { self.runBgActions(bgTextureName: "bg2") }
    let bg3Action = SKAction.run { self.runBgActions(bgTextureName: "bg3") }
    let waitAction = SKAction.wait(forDuration: 10)
    let sequence = SKAction.sequence([bg1Action, waitAction, bg2Action, waitAction, bg3Action, waitAction])
    let repeatForeverAction = SKAction.repeatForever(sequence)
    self.run(repeatForeverAction)
}

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