ios - 如何与其父 SKShapeNode 一起旋转 SKLabelNode？

Question

当按下屏幕时，使用以下代码创建的球:

var n = 1
func addBall(_ x:CGFloat){
    let numShape =  SKShapeNode(circleOfRadius: 30)
    numShape.name  = "ball"
    numShape.position = CGPoint(x: x, y: frame.maxY-40)
    numShape.physicsBody = SKPhysicsBody(circleOfRadius: 30)
    numShape.fillColor = SKColor.white
    numShape.physicsBody?.density = 0.1
    numShape.physicsBody?.affectedByGravity = true
    numShape.physicsBody?.friction = 0;
    numShape.physicsBody?.restitution = 0.6
    numShape.physicsBody?.allowsRotation = true
    numShape.physicsBody?.isDynamic = true

    let numLabel = SKLabelNode(fontNamed: "Helvetica")
    numLabel.text = "\(n)"
    numLabel.name = "\(n)"
    numLabel.fontColor = .red
    numLabel.position = CGPoint(x: 0, y: 0)
    numLabel.verticalAlignmentMode = .center

    numShape.addChild(numLabel)
    self.addChild(numShape)

    n += 1
}

球可以旋转，但它们的子节点 numlabel 不随它们一起旋转。我尝试像下面这样更新他们的 zRotation:

   override func update(_ currentTime: TimeInterval) {
        self.enumerateChildNodes(withName: "ball") {
            node, stop in
            if (node is SKShapeNode) {
                let ball = node as! SKShapeNode
                let num = ball.children[0]
                num.zRotation = ball.zRotation
            }
        }

    }

他们仍然拒绝轮换。如果我像 num.zRotation = 2 那样直接更改 zRotation，它们就会起作用。

如何让它们与 SKShapeNode 一起旋转？

谢谢。

Answer 1

您需要将摩擦力设置为 0 以外的数字。

另外，关于形状节点的性能:

查看 50 个形状底部的绘制计数:

for _ in 1...50 {
  let x = arc4random_uniform(UInt32(frame.maxX));
  let xx = CGFloat(x) - size.width/4

  let y = arc4random_uniform(UInt32(frame.maxY))
  let yy = CGFloat(y) - size.width/4

  let shape = SKShapeNode(circleOfRadius: 50)
  shape.strokeColor = .blue
  shape.lineWidth = 1
  shape.position = CGPoint(x: xx, y: yy)
  addChild(shape)
}

---

但现在将其与这张只有 2 次绘制且仅进行几行重构的图像进行比较:

func addFiftySprites() {

  let shape = SKShapeNode(circleOfRadius: 50)
  shape.strokeColor = .blue
  shape.lineWidth = 1

  let texture = SKView().texture(from: shape)

  for _ in 1...50 {
    let x = arc4random_uniform(UInt32(frame.maxX));
    let xx = CGFloat(x) - size.width/4

    let y = arc4random_uniform(UInt32(frame.maxY))
    let yy = CGFloat(y) - size.width/4

    let sprite = SKSpriteNode(texture: texture)
    sprite.position = CGPoint(x: xx, y: yy)

    addChild(sprite)
  }
}

---

这里的魔法是使用 let texture = SKView().texture(from: <SKNode>)将形状转换为 Sprite :) let sprite = SKSpriteNode(texture: texture)