Question

好的，所以我有一个Cgpoints数组，我将sprite节点移动到迭代数组。距离下一点的精灵距离随每个点而变化

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    <button>button</button>
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    <button>button</button>
	</li>
</ul>

我的问题是静态持续时间，具体取决于精灵以更慢/更快的速度移动的位置。无论精灵必须行驶的距离我都需要有恒定的速度。

如何根据精灵与终点的距离改变SKAction速度？

Answer 1

这需要使用距离公式。现在要保持恒定速度，您需要确定要移动的每秒点数（pps）。

基本上公式变为距离/ pps

所以，假设我们想要旅行（0,0）到（0,300）（这是300分，所以它需要我们2秒）

伪代码：

让持续时间= sqrt（（0 - 0）*（0 - 0）+（0 - 300）*（0 - 300））/（150）
持续时间= sqrt（90000）/（150）
持续时间= 300/150
持续时间= 2

然后你会将它弹出到你的移动动作中：

let action = SKAction.move(to: points[i], duration: duration)

您的Swift代码应如下所示：

let pps = 150 //define points per second
func moveGuy() {
    var actions = [SKAction]()
    var previousPoint = guy.position // let's make sprite the starting point
    for point in points
    {
      //calculate the duration using distance / pps
      //pow seems to be slow and some people have created ** operator in response, but will not show that here
      let duration = sqrt((point.x - previousPoint.x) * (point.x - previousPoint.x) + 
                     (point.y - previousPoint.y) * (point.y - previousPoint.y)) / pps

      //assign the action to the duration
      let action = SKAction.move(to: point, duration: duration)
      action.timingMode = .easeInEaseOut
      actions.append(action)
      previousPoint = point
    }   
    guy.run(actions)
}

//Since the entire path is done in moveGuy now, we no longer want to be doing it on update, so instead we do it during the mouse click event
//I do not know OSX, so I do not know how mouse down really works, this may need to be fixed
//Also I am not sure what is suppose to happen if you click mouse twice,
//You will have to handle this because it will run 2 actions at once if not done
override func mouseDown(event:NSEvent)
{
    moveGuy()
}

现在你会注意到你的精灵在每次迭代时都在跑步和减速，你可能不希望这样，所以对于你的计时模式，你可能想要这样做

//Use easeInEaseOut on our first move if we are only moving to 1 point
if points.count == 1
{
    action.timingMode = .easeInEaseOut
}
//Use easeIn on our first move unless we are only moving to 1 point
else if previousPoint == sprite.position
{
    action.timingMode = .easeIn
}
//Use easeOut on our last move unless we are only moving to 1 point
else if point == point.last
{
    action.timingMode = .easeOut
}
//Do nothing
else
{
    action.timingMode = .linear
}

Answer 2

您必须创建一个新的SKAction，其持续时间根据要移动的距离和要移动的节点的速度（以点/ s为单位）计算得出。

精灵套件：如何根据距离改变滑行持续时间？

2 个答案: