move a background endless in swift 4

Question

Hi i'm trying to move a background endlessly, but i have a little problem when i simulate the code.

This is my code

didMove(to view: SKView) {

    for i  in 0...1 {
        let backgroundNEW = SKSpriteNode(imageNamed: "New_Background")
        backgroundNEW.size = self.size
        backgroundNEW.anchorPoint = CGPoint(x: 0.5 , y: 0)
        backgroundNEW.position = CGPoint(x: self.size.width  ,  y: self.size.height  * CGFloat(i))
        backgroundNEW.zPosition = -1
        backgroundNEW.name = "test"
        addChild(backgroundNEW)
    }
}

and

 var lastUpdateTime : TimeInterval = 0
 var deltaFrameTime : TimeInterval = 0
 var amountToMovePerSecond : CGFloat = 200.0

override func update(_ currentTime: TimeInterval){

    if lastUpdateTime == 0{
        lastUpdateTime = currentTime
    }
    else {
        deltaFrameTime = currentTime - lastUpdateTime
        lastUpdateTime = currentTime
    }

    let amountToMoveBackground =  amountToMovePerSecond * CGFloat(deltaFrameTime)

    self.enumerateChildNodes(withName: "test") {
        backgroundNEW, stop in

        backgroundNEW.position.x -= amountToMoveBackground

        if backgroundNEW.position.x < -self.size.height{
            backgroundNEW.position.x += self.size.height*2
        }
    }
}

i got this simulation : https://gyazo.com/63ce327ce9bc0a14199f411ac187de25

my problem is the black background i dont know how i can replace it to do the background moving endless .

Answer 1

Here is my code I am using to scroll a background infinitely (assuming you are using SpriteKit?) You need two backgrounds to give it the look and feel of an infinitely scrolling background. I updated it to work for 3 backgrounds to provide an infinite scroll.

outside your didMove(toView:) method

var bg = SKSpriteNode()
var bg2 = SKSpriteNode()
var bg3 = SKSpriteNode()

var parallax = SKAction()

setting up your backgrounds inside your didMove(toView:) method

bg = SKSpriteNode(imageNamed: "texture")
bg.position = CGPoint(x: 0, y:0)
bg.zPosition = 3
bg.size = CGSize(width:Int, height:Int) //make sure to set the width to self.frame.size.width, the height can be anything

bg2 = SKSpriteNode(imageNamed: "texture")
bg2.position = CGPoint(x: self.frame.size.width, y:0)
bg2.zPosition = 3
bg2.size = CGSize(width:Int, height:Int) //make sure to set the width to self.frame.size.width, the height can be anything

bg3 = SKSpriteNode(imageNamed: "texture")
bg3.position = CGPoint(x: self.frame.size.width + bg2.position.x, y:0)
bg3.zPosition = 3
bg3.size = CGSize(width:Int, height:Int) //make sure to set the width to self.frame.size.width, the height can be anything

self.addChild(bg)
self.addChild(bg2)
self.addChild(bg3)

Now to handle the scrolling of the backgrounds

parallax = SKAction.repeatForever(SKAction.move(by: CGVector(dx: -self.frame.size.width, dy: 0), duration: 20)) 
//higher duration moves it slower, lower duration moves it faster

bg.run(parallax)
bg2.run(parallax)
bg3.run(parallax)

Finally, in the update(currentTime:) method that updates before each frame

override func update(_ currentTime: TimeInterval) {
    // Called before each frame is rendered
    if bg.position.x <= -self.frame.size.width {
        bg.position.x = self.frame.size.width * 2
        //this ensures that your backgrounds line up perfectly 
    }
    if bg2.position.x <= -self.frame.size.width {
        bg2.position.x = self.frame.size.width * 2
        //this ensures that your backgrounds line up perfectly
    }
    if bg3.position.x <= -self.frame.size.width {
        bg3.position.x = self.frame.size.width * 2
        //this ensures that your backgrounds line up perfectly
    }
}

If you have any questions, ask them so I can help you out.