ios - Swift Infinite Scroller FPS 代码效率低下

Question

我在制作无限滚动条时遇到问题。 Google 结果显示我一定是使用了低效代码，因为我在模拟器和 iPhone 5(物理设备)上得到了大约 14-15 FPS，我得到了相同的结果。我将不胜感激有关使我的代码更高效的一些提示。也许合并功能？缩小图像并缩放它们？当前背景图像为 1136x750。平台大约为 200x75。

import SpriteKit

class GameScene: SKScene, SKPhysicsContactDelegate {
    let screenSize: CGRect = UIScreen.mainScreen().bounds
    let backgroundVelocity : CGFloat = 6.0


    override func didMoveToView(view: SKView) {
        /* Setup your scene here */
        self.backgroundColor = SKColor.whiteColor()
        self.initializingScrollingBackground()
        self.startPlatforms()


        // Making self delegate of physics world
        self.physicsWorld.gravity = CGVectorMake(0, 0)
        self.physicsWorld.contactDelegate = self
    }


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

        self.moveBackground()
        self.movePlatforms()
    }

    func startPlatforms(){
        for var n = 0; n < 1000; ++n {
        let plat = SKSpriteNode(imageNamed: "platform")
        plat.position = CGPoint(x: n * (Int(plat.size.width)+125), y: 90)
        plat.anchorPoint = CGPointZero
        plat.name = "platform"
        self.addChild(plat)

        }

    }
    func movePlatforms() {
        self.enumerateChildNodesWithName("platform", usingBlock: { (node, stop) -> Void in
            if let plat = node as? SKSpriteNode {
                plat.position = CGPoint(x: plat.position.x - self.backgroundVelocity, y: plat.position.y)
                if(plat.position.x <= -200 ){
                        node.removeFromParent()

                }
            }
        })
    }


    func initializingScrollingBackground() {
        for var index = 0; index < 2; ++index {
            let bg = SKSpriteNode(imageNamed: "bg")
            bg.position = CGPoint(x: index * Int(bg.size.width), y: -55)
            bg.anchorPoint = CGPointZero
            bg.name = "background"
            self.addChild(bg)
        }

    }

    func moveBackground() {
        self.enumerateChildNodesWithName("background", usingBlock: { (node, stop) -> Void in
            if let bg = node as? SKSpriteNode {
                bg.position = CGPoint(x: bg.position.x - self.backgroundVelocity, y: bg.position.y)

                // Checks if bg node is completely scrolled off the screen, if yes, then puts it at the end of the other node.
                if bg.position.x <= -bg.size.width {
                    bg.position = CGPointMake(bg.position.x + bg.size.width * 2, bg.position.y)
                }
            }
        })
    }

}

Answer 1

编写游戏时要记住的一个基本事实:

Every code you want to run from the update method (so every frame) must be fast.

现在，让我们看看您的代码。

1。分组节点

如果你有一堆节点一起移动，而不是手动移动每个节点，你应该添加一个公共(public)的 parent给他们，然后只移动 parent .

所以这个

func startPlatforms(){
    for var n = 0; n < 1000; ++n {
        let plat = SKSpriteNode(imageNamed: "platform")
        plat.position = CGPoint(x: n * (Int(plat.size.width)+125), y: 90)
        plat.anchorPoint = CGPointZero
        plat.name = "platform"
        self.addChild(plat)
    }
}

变成这样

private let platformParent = SKNode()
func createPlatforms() {
    self.addChild(platformParent)
    for n in 0...999 {
        let plat = SKSpriteNode(imageNamed: "platform")
        plat.position = CGPoint(x: n * (Int(plat.size.width)+125), y: 90)
        plat.anchorPoint = CGPointZero
        plat.name = "platform"
        platformParent.addChild(plat)
    }
}

2。使用 SKAction 移动

现在你不需要移动每个平台，你可以运行一个SKAction只移动 parent 。 children会自动跟随他。

所以这个

func movePlatforms() {
    self.enumerateChildNodesWithName("platform", usingBlock: { (node, stop) -> Void in
        if let plat = node as? SKSpriteNode {
            plat.position = CGPoint(x: plat.position.x - self.backgroundVelocity, y: plat.position.y)
            if(plat.position.x <= -200 ){
                node.removeFromParent()

            }
        }
    })
}

变成这样

// to be called only once!
func beginMovingParentPlatform() {
    let moveToLeft = SKAction.moveToX(-200, duration: 5) // please change the 2 params (-200 and 5) as you need
    self.platformParent.runAction(moveToLeft) {
        self.removeAllChildren()
    }
}

当然还有这个

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

    self.moveBackground()
    self.movePlatforms()
}

变成这样

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

    self.moveBackground()
    // self.movePlatforms()
}

现在您的代码应该会更快。

您可以将相同的逻辑应用于 moveBackground .

记住，不要手动移动节点。使用 SKActions ，它们比您(或我)可以编写的代码更优化。