ios - 如何用SKKeyframeSequence绘制渐变 : as per Apple docs

Question

SKKeyframeSequence 上的 Apple 文档具有旨在创建渐变的简短示例代码:

let colorSequence = SKKeyframeSequence(keyframeValues: [SKColor.green,
                                                        SKColor.yellow,
                                                        SKColor.red,
                                                        SKColor.blue],
                                       times: [0, 0.25, 0.5, 1])
colorSequence.interpolationMode = .linear
stride(from: 0, to: 1, by: 0.001).forEach {
    let color = colorSequence.sample(atTime: CGFloat($0)) as! SKColor
}

当与某种绘图系统结合使用时，据说输出如下: 如何从演示代码中的颜色序列采样中得出这一点？

ps 我不知道如何用 SpriteKit 对象绘制它，因此没有尝试代码。我不是要代码，只是关于如何使用这个颜色“数组”来创建可用作 SpriteKit 中的纹理的渐变的答案。

Answer 1

由于某些原因颜色不同，但这是我使用他们的源代码得出的结果:

PG 设置:

import SpriteKit
import PlaygroundSupport

let sceneView = SKView(frame: CGRect(origin: CGPoint.zero, size: CGSize(width: 1000, height: 450)))
let scene     = SKScene(size: CGSize(width: 1000, height: 450))

LOADSCENE: do {
  scene.backgroundColor = .white
  scene.anchorPoint = CGPoint(x: 0, y: 0.5)
  scene.physicsWorld.gravity = CGVector.zero
  sceneView.presentScene(scene)

  PlaygroundPage.current.liveView = sceneView
}

解决方法:

// Utility func:
func drawLine(from point1: CGPoint, to point2: CGPoint, color: SKColor) {
  let linePath = CGMutablePath()
  linePath.move(to: point1)
  linePath.addLine(to: point2)

  let newLine = SKShapeNode(path: linePath)
  newLine.strokeColor = color
  newLine.lineWidth = 1
  newLine.zPosition = 10
  scene.addChild(newLine)
  newLine.position.x = point1.x

}

// Holds our soon-to-be-generated colors:
var colors = [SKColor]()

LOADCOLORS: do {
  let colorSequence = SKKeyframeSequence(keyframeValues: [SKColor.green,
                                                          SKColor.yellow,
                                                          SKColor.red,
                                                          SKColor.blue],
                                         times: [0, 0.25, 0.5, 1])

  colorSequence.interpolationMode = .linear
  stride(from: 0, to: 1, by: 0.001).forEach {
    colors.append(colorSequence.sample(atTime: CGFloat($0)) as! SKColor)
  }
}

DRAWGRAD: do {
  for i in 1...999 {
    let p1 = CGPoint(x: CGFloat(i), y: scene.frame.minY)
    let p2 = CGPoint(x: CGFloat(i), y: scene.frame.maxY)
    drawLine(from: p1, to: p2, color: colors[i])
  }

  print("Give me my 25 cookie points, please and TY")
}

然后您应该能够将其作为纹理获取:

let texture = sceneView.texture(from: scene)

出于某种原因，在我的 2.6ghz 的 gen2 i5 上渲染这花了大约一百万年的时间。将不得不对此进行调查，除非它只是一个 PG 错误......