swift - 如何在 SpriteKit 中创建逼真的纺车

Question

我正在尝试通过 SKAction 创建一个旋转的幸运轮 Action 。我有一个用作轮子的 SKNode，这个 SKNode 是一个分成四个部分的圆(每个部分有不同的颜色)。我还设置了一个 SKAction(重复 10 个计数)，它围绕固定点(节点的中心)旋转 SKNode。问题是 Action 运行良好但突然停止并且没有减速 - 就像一个真正的轮子。我真的不知道如何设置这个动画，我的意思是在 Action 停止之前减慢旋转速度。 到目前为止，这是我的代码:

class GameScene: SKScene {

let colors = [SKColor.yellow, SKColor.red, SKColor.blue, SKColor.purple]


override func didMove(to view: SKView) {
    createWheel()

    let sq = CGRect(x: size.width/2, y: size.height/2, width: 300, height: 300)
    let sqx = SKShapeNode(rect: sq)
    sqx.lineWidth = 2
    sqx.fillColor = .clear
    sqx.setScale(1.0)
    addChild(sqx)
    }

func createWheel() {
    let path = UIBezierPath()
    path.move(to: CGPoint(x: 0, y: 0))
    path.addLine(to: CGPoint(x: 0, y: -200))
    path.addArc(withCenter: CGPoint.zero,radius: 200,startAngle: CGFloat(0.0), endAngle: CGFloat(3.0 * Double.pi / 2),clockwise: false)
    path.addLine(to: CGPoint(x: 200, y: 0))

    let obstacle = obstacleByDuplicatingPath(path, clockwise: true)
    obstacle.position = CGPoint(x: size.width/2, y: size.height/2)
    addChild(obstacle)

    let rotateAction = SKAction.rotate(byAngle: CGFloat((3.0 * CGFloat(Double.pi / 2)) - 90), duration: 0.5)
    //obstacle.run(SKAction.repeatForever(rotateAction))
    obstacle.run(SKAction.repeat(rotateAction, count: 10))


}

func obstacleByDuplicatingPath(_ path: UIBezierPath, clockwise: Bool) -> SKNode {
    let container = SKNode()

    var rotationFactor = CGFloat(Double.pi / 2)
    if !clockwise {
        rotationFactor *= -1
    }

    for i in 0...3 {
        let section = SKShapeNode(path: path.cgPath)
        section.fillColor = colors[i]
        section.strokeColor = colors[i]
        section.zRotation = rotationFactor * CGFloat(i);

        let origin = CGPoint(x: 0.0, y: 0.0)
        switch i {
        case 0:
            section.position = CGPoint(x: (origin.x + 10), y: (origin.y - 10))
        case 1:
            section.position = CGPoint(x: (origin.x + 10), y: (origin.y + 10))
        case 2:
            section.position = CGPoint(x: (origin.x - 10), y: (origin.y + 10))
        case 3:
            section.position = CGPoint(x: (origin.x - 10), y: (origin.y - 10))
        default:
            print("bolbol")

        }

        container.addChild(section)
    }
    return container
}

编辑: 我在考虑它，我尝试通过 SKAction 来做，我设置了另一个 Action ，但这次我将它们的持续时间设置为很长。首先它运行一个持续时间为 0.5 的 Action ，然后是 2，最后是 4。我看起来很不错，但仍然不如我想要的那样流畅。 这是我的代码:

        let rotateAction = SKAction.rotate(byAngle: CGFloat(2.0 * CGFloat(M_PI)), duration: 0.5)
    let rotateAction2 = SKAction.rotate(byAngle: CGFloat(2.0 * CGFloat(M_PI)), duration: 2)
    let rotateAction3 = SKAction.rotate(byAngle: CGFloat(2.0 * CGFloat(M_PI)), duration: 4)
    let wait = SKAction.wait(forDuration: 5)
    let g1 = SKAction.repeat(rotateAction, count: 10)
    let group = SKAction.group([wait, g1, rotateAction2, rotateAction3])

你怎么看？有什么办法可以做得更好吗？？

编辑 2: 继续 @Ali Beadle 的回答，我尝试通过物理体来完成，现在的问题是当我在屏幕上拖动手指时，SKShapeNode(形状)继续旋转并且永不停止。你能检测出哪里出了问题吗？

class GameScene: SKScene {
var start: CGPoint?
var end:CGPoint?
var startTime: TimeInterval?
let shape = SKShapeNode.init(rectOf: CGSize(width: 150, height: 150))

override func didMove(to view: SKView) {

    self.physicsWorld.gravity = CGVector(dx: 0, dy: -9.8)
    let sceneBody = SKPhysicsBody.init(edgeLoopFrom: self.frame)
    sceneBody.friction = 0
    self.physicsBody = sceneBody


    shape.fillColor = SKColor.red
    shape.position = CGPoint(x: self.size.width/2, y: self.size.height/2)
    shape.physicsBody = SKPhysicsBody.init(rectangleOf: CGSize(width: 50, height: 50))
    shape.physicsBody?.affectedByGravity = false
    shape.physicsBody?.isDynamic = true
    addChild(shape)
}


override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    guard let touch = touches.first else {return}
    self.start = touch.location(in: self)
    self.startTime = touch.timestamp
}

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
    guard let touch = touches.first else {return}
    self.end = touch.location(in: self)
    var dx = ((self.end?.x)! - (self.start?.x)!)
    var dy = ((self.end?.y)! - (self.start?.y)!)

    let magnitude:CGFloat = sqrt(dx*dx+dy*dy)
    if(magnitude >= 25){
        let dt:CGFloat = CGFloat(touch.timestamp - self.startTime!)
        if dt > 0.1 {
            let speed = magnitude / dt
            dx = dx / magnitude
            dy = dy / magnitude
            print("dx: \(dx), dy: \(dy), speed: \(speed) ")

        }
    }
    let touchPosition = touch.location(in: self)
    if touchPosition.x < (self.frame.width / 2) {
        self.shape.physicsBody?.angularVelocity = 10
        self.shape.physicsBody?.applyAngularImpulse(-180)
    } else {
        self.shape.physicsBody?.angularVelocity = 10
        self.shape.physicsBody?.applyAngularImpulse(180)
    }
}}

Answer 1

我在 Spritekit 中创建了一个开源奖品纺车，它使用物理学来实现逼真的运动和挡板控制。它还允许用户拖动轮子旋转或通过插入轮子的中心产生随机旋转。

https://github.com/hsilived/SpinWheel