Question

我可以按如下方式创建自定义SKAction：

extension SKAction {
  class func move(from: CGPoint, halfWayTo: CGPoint, duration: TimeInterval) -> SKAction {
    let midPoint = CGPoint(x: (from.x + halfWayTo.x)/2, y: (from.y + halfWayTo.y)/2 )
    return SKAction.move(to: midPoint, duration: duration)
  }
}

然后我这样使用：

//Setup
let node = SKNode()
node.position = CGPoint(x: 50, y: 50)
let destination = CGPoint(x: 100, y: 100)

//Move from node's current position half way towards the destination
let action = SKAction.move(from: node.position, halfWayTo: destination, duration: 1)
node.run(action)

但符合标准：

SKAction.move(to: destination, duration: 1)

我宁愿能够说：

let action = SKAction.move(halfWayTo: destination, duration: 1)
node.run(action)

但我不知道如何参考节点＆＃39;从自定义SKAction内部，以便我可以获得它的位置并计算中途点？

Answer 1

您使用self。

extension SKAction {
  class func move(halfWayTo: CGPoint, duration: TimeInterval) -> SKAction {
    let from = self.position
    let midPoint = CGPoint(x: (from.x + halfWayTo.x)/2, y: (from.y + halfWayTo.y)/2 )
    return SKAction.move(to: midPoint, duration: duration)
  }
}

然后打电话（如你所说）

node.move(halfWayTo: B, duration: 1)

Answer 2

我仍然不确定SKAction是否会引用它所应用的节点 - 即使它正在运行 - 或者即使它确实存在 - 我也不确定是否存在＆＃39 ;访问它的方式。如果有人知道确实如此，请告诉我。

我想到了一种方法如下：

不是扩展SKAction，而是按如下方式扩展SKNode：

extension SKNode {
  func move(halfWayTo: CGPoint, duration: TimeInterval) -> SKAction {
    let from = self.position
    let midPoint = CGPoint(x: (from.x + halfWayTo.x)/2, y: (from.y + halfWayTo.y)/2 )
    return SKAction.move(to: midPoint, duration: duration)
  }
}

然后使用如下：

//Setup
let node = SKNode()
node.position = CGPoint(x: 50, y: 50)
let destination = CGPoint(x: 100, y: 100)

//Move from node's current position half way towards the destination
let action2 = node.move(halfWayTo: destination, duration: 1)
node.run(action2)

如何从自定义SKAction Swift

2 个答案: