我正在尝试使用 CAReplicatorLayer 对象为我的背景视图实现这种马赛克灯光秀效果： https ://downloops.com/stock-footage/mosaic-light-show-blue-illuminated-pixel-grid-looping-background/
每个图块/CALayer 都是水平和垂直复制的单个图像。那部分我已经完成了。
在我看来，这项任务至少分为 4 个单独的部分：
- 选择一个随机瓷砖
- 为所选图块选择随机范围的颜色偏移
- 在指定的持续时间内应用该颜色偏移（以秒为单位）
- 如果随机颜色偏移超过特定阈值，则应用带有颜色偏移动画的发光效果。
但我实际上不确定这是否是正确的算法。
我当前的代码取自本教程： https ://www.swiftbysundell.com/articles/ca-gems-using-replicator-layers-in-swift/
动画不是我的强项，我实际上不知道如何在所有图块上应用连续/重复动画。这是我当前的代码：
@IBOutlet var animationView: UIView!
func cleanUpAnimationView() {
self.animationView.layer.removeAllAnimations()
self.animationView.layer.sublayers?.removeAll()
}
/// Start a background animation with a replicated pattern image in tiled formation.
func setupAnimationView(withPatternImage patternImage: UIImage, animate: Bool = true) {
// Tutorial: https://www.swiftbysundell.com/articles/ca-gems-using-replicator-layers-in-swift/
let imageSize = patternImage.size.halve
self.cleanUpAnimationView()
// Animate pattern image
let replicatorLayer = CAReplicatorLayer()
replicatorLayer.frame.size = self.animationView.frame.size
replicatorLayer.masksToBounds = true
self.animationView.layer.addSublayer(replicatorLayer)
// Give the replicator layer a sublayer to replicate
let imageLayer = CALayer()
imageLayer.contents = patternImage.cgImage
imageLayer.frame.size = imageSize
replicatorLayer.addSublayer(imageLayer)
// Tell the replicator layer how many copies (or instances) of the image needs to be rendered. But we won't see more than one since they are, per default, all rendered/stacked on top of each other.
let instanceCount = self.animationView.frame.width / imageSize.width
replicatorLayer.instanceCount = Int(ceil(instanceCount))
// Instance offsets & transforms is needed to move them
// 'CATransform3D' transform will be used on each instance: shifts them to the right & reduces the red & green color component of each instance's tint color.
// Shift each instance by the width of the image
replicatorLayer.instanceTransform = CATransform3DMakeTranslation(imageSize.width, 0, 0)
// Reduce the red & green color component of each instance, effectively making each copy more & more blue while horizontally repeating the gradient pattern
let colorOffset = -1 / Float(replicatorLayer.instanceCount)
replicatorLayer.instanceRedOffset = colorOffset
replicatorLayer.instanceGreenOffset = colorOffset
//replicatorLayer.instanceBlueOffset = colorOffset
//replicatorLayer.instanceColor = UIColor.random.cgColor
// Extend the original pattern to also repeat vertically using another tint color gradient
let verticalReplicatorLayer = CAReplicatorLayer()
verticalReplicatorLayer.frame.size = self.animationView.frame.size
verticalReplicatorLayer.masksToBounds = true
verticalReplicatorLayer.instanceBlueOffset = colorOffset
self.animationView.layer.addSublayer(verticalReplicatorLayer)
let verticalInstanceCount = self.animationView.frame.height / imageSize.height
verticalReplicatorLayer.instanceCount = Int(ceil(verticalInstanceCount))
verticalReplicatorLayer.instanceTransform = CATransform3DMakeTranslation(0, imageSize.height, 0)
verticalReplicatorLayer.addSublayer(replicatorLayer)
guard animate else { return }
// Set both the horizontal & vertical replicators to add a slight delay to all animations applied to the layer they're replicating
let delay = TimeInterval(0.1)
replicatorLayer.instanceDelay = delay
verticalReplicatorLayer.instanceDelay = delay
// This will make the image layer change color
let animColor = CABasicAnimation(keyPath: "instanceRedOffset")
animColor.duration = animationDuration
animColor.fromValue = verticalReplicatorLayer.instanceRedOffset
animColor.toValue = -1 / Float(Int.random(replicatorLayer.instanceCount-1))
animColor.autoreverses = true
animColor.repeatCount = .infinity
replicatorLayer.add(animColor, forKey: "colorshift")
let animColor1 = CABasicAnimation(keyPath: "instanceGreenOffset")
animColor1.duration = animationDuration
animColor1.fromValue = verticalReplicatorLayer.instanceGreenOffset
animColor1.toValue = -1 / Float(Int.random(replicatorLayer.instanceCount-1))
animColor1.autoreverses = true
animColor1.repeatCount = .infinity
replicatorLayer.add(animColor1, forKey: "colorshift1")
let animColor2 = CABasicAnimation(keyPath: "instanceBlueOffset")
animColor2.duration = animationDuration
animColor2.fromValue = verticalReplicatorLayer.instanceBlueOffset
animColor2.toValue = -1 / Float(Int.random(replicatorLayer.instanceCount-1))
animColor2.autoreverses = true
animColor2.repeatCount = .infinity
replicatorLayer.add(animColor2, forKey: "colorshift2")
}