SpriteKit中具有深度的背景动画

Question

我正在使用 Swift 和 SpriteKit 构建我的第一个游戏，并且想要添加背景。游戏发生在太空中，所以我想让背景中的星星以不同的速度移动。目前，我希望通过让较大的星星在屏幕上的移动速度比较小的星星更快来获得 3D 外观。有没有一种有效的方法来做到这一点，而不是像这样创建一个 SKNode 子类并将其作为子类添加到DidMoveToView 的开头？看起来这种方法非常密集，但我想我会在一遍又一遍地回收同一个图像之前尝试一下。

class BackGroundAnimation:SKNode{

let theView:SKView
init(aView:SKView){

    theView = aView

    super.init()

    animate()
}


func animate(){


    for _ in 1...200{

        let randomSize = random(1, max: 3)
        var randomPosx = random(1,max: 1000)
        randomPosx = randomPosx/1000.0
        var randomPosy = random(1,max: 1000)
        randomPosy = randomPosy/1000.0

        let star:SKSpriteNode = SKSpriteNode(texture:starTexture)
        star.setScale(randomSize/60.0)



        star.position = CGPoint(x:(theView.scene?.size.width)! * randomPosx,y:(theView.scene?.size.width)! * randomPosy)//    (self.scene.size.width)*randomPosx, y:(self.scene.size.height) * randomPosy)

        //star.position = CGPoint(x: 200,y: 200)

        star.physicsBody = SKPhysicsBody(circleOfRadius: star.size.width/2 )
        star.physicsBody?.collisionBitMask = 0
        star.physicsBody?.categoryBitMask = 0
        star.physicsBody?.contactTestBitMask = 0

        star.physicsBody?.linearDamping = 0
        star.physicsBody?.velocity = CGVector(dx:1 * randomSize, dy:0)
        star.name = "star"

        //addChild(star)
        self.addChild(star)
        self.moveToParent(self.scene!)


    }


}




required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

}

任何帮助都会很棒。

Answer 1

为 Swift 4 / iOS 11

更新了 @JozemiteApps 解决方案

在你的班级的任何地方添加这个函数。

//Creates a new star field
func starfieldEmitterNode(speed speed: CGFloat, lifetime: CGFloat, scale: CGFloat, birthRate: CGFloat, color: SKColor) -> SKEmitterNode {
    let star = SKLabelNode(fontNamed: "Helvetica")
    star.fontSize = 80.0
    star.text = "✦"
    let textureView = SKView()
    let texture = textureView.texture(from: star)
    texture!.filteringMode = .nearest

    let emitterNode = SKEmitterNode()
    emitterNode.particleTexture = texture
    emitterNode.particleBirthRate = birthRate
    emitterNode.particleColor = color
    emitterNode.particleLifetime = lifetime
    emitterNode.particleSpeed = speed
    emitterNode.particleScale = scale
    emitterNode.particleColorBlendFactor = 1
    emitterNode.position = CGPoint(x: frame.midX, y: frame.maxY)
    emitterNode.particlePositionRange = CGVector(dx: frame.maxX, dy: 0)
    emitterNode.particleSpeedRange = 16.0

    //Rotates the stars
    emitterNode.particleAction = SKAction.repeatForever(SKAction.sequence([
        SKAction.rotate(byAngle: CGFloat(-Double.pi/4), duration: 1),
        SKAction.rotate(byAngle: CGFloat(Double.pi/4), duration: 1)]))

    //Causes the stars to twinkle
    let twinkles = 20
    let colorSequence = SKKeyframeSequence(capacity: twinkles*2)
    let twinkleTime = 1.0 / CGFloat(twinkles)
    for i in 0..<twinkles {
        colorSequence.addKeyframeValue(SKColor.white,time: CGFloat(i) * 2 * twinkleTime / 2)
        colorSequence.addKeyframeValue(SKColor.yellow, time: (CGFloat(i) * 2 + 1) * twinkleTime / 2)
    }
    emitterNode.particleColorSequence = colorSequence

    emitterNode.advanceSimulationTime(TimeInterval(lifetime))
    return emitterNode
}

然后也添加这个功能。这是创建星星层的函数。只需调用这个函数，例如在 didMoveToView 中。

func createStarLayers() {
        //A layer of a star field
        let starfieldNode = SKNode()
        starfieldNode.name = "starfieldNode"
        starfieldNode.addChild(starfieldEmitterNode(speed: -48, lifetime: size.height / 23, scale: 0.2, birthRate: 1, color: SKColor.lightGray))
        addChild(starfieldNode)

        //A second layer of stars
        var emitterNode = starfieldEmitterNode(speed: -32, lifetime: size.height / 10, scale: 0.14, birthRate: 2, color: SKColor.gray)
        emitterNode.zPosition = -10
        starfieldNode.addChild(emitterNode)

        //A third layer
        emitterNode = starfieldEmitterNode(speed: -20, lifetime: size.height / 5, scale: 0.1, birthRate: 5, color: SKColor.darkGray)
        starfieldNode.addChild(emitterNode)
    }

Answer 2

不使用粒子的方法是创建图层，然后移动各个图层

所以创建一个背景 SKNode，用你的背景精灵填充它

创建一个前景 SKNode，用你的前景精灵填充它

添加背景作为前景的子级，给它的 zPosition 至少为 -1

然后你移动前景，无论你移动前景，你都会向相反的方向移动背景，通常是它的较小百分比（我喜欢使用一半）。如果您的前景向左移动 10 像素，则您将背景向右移动 5 像素

由于您的所有节点都在这些层内，因此当您移动层时所有节点都会移动

Answer 3

正如我在评论中提到的，您可以使用粒子创建漂亮的视差背景。

在你的班级的任何地方添加这个函数。

//Creates a new star field
func starfieldEmitterNode(speed speed: CGFloat, lifetime: CGFloat, scale: CGFloat, birthRate: CGFloat, color: SKColor) -> SKEmitterNode {
    let star = SKLabelNode(fontNamed: "Helvetica")
    star.fontSize = 80.0
    star.text = "✦"
    let textureView = SKView()
    let texture = textureView.textureFromNode(star)
    texture!.filteringMode = .Nearest

    let emitterNode = SKEmitterNode()
    emitterNode.particleTexture = texture
    emitterNode.particleBirthRate = birthRate
    emitterNode.particleColor = color
    emitterNode.particleLifetime = lifetime
    emitterNode.particleSpeed = speed
    emitterNode.particleScale = scale
    emitterNode.particleColorBlendFactor = 1
    emitterNode.position = CGPoint(x: CGRectGetMidX(frame), y: CGRectGetMaxY(frame))
    emitterNode.particlePositionRange = CGVector(dx: CGRectGetMaxX(frame), dy: 0)
    emitterNode.particleSpeedRange = 16.0

    //Rotates the stars
    emitterNode.particleAction = SKAction.repeatActionForever(SKAction.sequence([
        SKAction.rotateByAngle(CGFloat(-M_PI_4), duration: 1),
        SKAction.rotateByAngle(CGFloat(M_PI_4), duration: 1)]))

    //Causes the stars to twinkle
    let twinkles = 20
    let colorSequence = SKKeyframeSequence(capacity: twinkles*2)
    let twinkleTime = 1.0 / CGFloat(twinkles)
    for i in 0..<twinkles {
        colorSequence.addKeyframeValue(SKColor.whiteColor(),time: CGFloat(i) * 2 * twinkleTime / 2)
        colorSequence.addKeyframeValue(SKColor.yellowColor(), time: (CGFloat(i) * 2 + 1) * twinkleTime / 2)
    }
    emitterNode.particleColorSequence = colorSequence

    emitterNode.advanceSimulationTime(NSTimeInterval(lifetime))
    return emitterNode
}

然后也添加这个功能。这是创建星星层的函数。只需调用这个函数，例如在 didMoveToView 中。

func createStarLayers() {
    //A layer of a star field
    let starfieldNode = SKNode()
    starfieldNode.name = "starfieldNode"
    starfieldNode.addChild(starfieldEmitterNode(speed: -48, lifetime: size.height / 23, scale: 0.2, birthRate: 1, color: SKColor.lightGrayColor()))
    addChild(starfieldNode)

    //A second layer of stars
    var emitterNode = starfieldEmitterNode(speed: -32, lifetime: size.height / 10, scale: 0.14, birthRate: 2, color: SKColor.grayColor())
    emitterNode.zPosition = -10
    starfieldNode.addChild(emitterNode)

    //A third layer
    emitterNode = starfieldEmitterNode(speed: -20, lifetime: size.height / 5, scale: 0.1, birthRate: 5, color: SKColor.darkGrayColor())
    starfieldNode.addChild(emitterNode)
}

这就是它的样子。