Macos 在OS X上使用NSPangestureRecogener拖动SKNode时闪烁

今天，我决定尝试一些新的闪亮（受iOS启发）的东西添加到OSX：手势识别器和精灵工具包。我已经在SKView中设置了一个NSPangestureRecogener，并使用它来拖动添加到场景中的节点。但是，当快速拖动节点时，我看到一个奇怪的闪烁

代码非常简单，在AppDelegate中设置所有内容

func applicationDidFinishLaunching(aNotification: NSNotification) {
    // Insert code here to initialize your application

    // Add and scene to the view and create a root node
    hostingView.presentScene(SKScene(size: CGSize(width: 1500.0, height: 1500.0)))
    rootNode = SKNode()

    // A a red circle
    let node = SKShapeNode(circleOfRadius: 50.0)
    node.lineWidth = 5.0
    node.strokeColor = NSColor.whiteColor()
    node.fillColor = NSColor.redColor()
    node.userInteractionEnabled = true
    rootNode?.addChild(node)
    hostingView.scene?.addChild(rootNode!)

}

然后实现手势识别器的动作方法

@IBAction func panAction(sender: AnyObject) {

    // Get the location in the view from the pan gesture recogniser
    let viewPoint = (sender as NSPanGestureRecognizer).locationInView(hostingView)

    // Convert from view -> scene -> root node coordinates
    if let scene = hostingView.scene {

        let scenePoint = hostingView.convertPoint(viewPoint, toScene:scene)

        if let root = self.rootNode {

                let rootNodePoint = scene.convertPoint(scenePoint, toNode: root)
                let node = root.nodeAtPoint(rootNodePoint)
                node.position = rootNodePoint
                println("Drag to point:", NSStringFromPoint(scenePoint))
                return
            }
        }

    println("Node was nil.")
}

---

如果要运行此项目，

当鼠标快速拖动并退出节点边界时，

nodeAtPoint:

正在返回背景节点。这导致了闪烁（谢谢@sangony）

解决方案是使用该值区分第一次触发时（

nsgestureRecognitizerStateStart

），更新时（

nsgestureRecognitizerStateChanged

），以及释放鼠标时（

nsgestureRecognitizerStateEnded

）。通过检查这些值，即使鼠标移动到节点边界之外，也可以缓存并更新正确的节点

更新的操作方法是

@IBAction func panAction(sender: AnyObject) {

    // Get the location in the view from the pan gesture recogniser
    let recognizer = (sender as NSPanGestureRecognizer)
    let viewPoint = recognizer.locationInView(hostingView)


    if let scene = hostingView.scene {

        // Convert from view -> scene
        let scenePoint = hostingView.convertPoint(viewPoint, toScene:scene)


        if let root = self.rootNode {

            // Convert from scene -> rootNode
            let rootNodePoint = scene.convertPoint(scenePoint, toNode: root)

            // Use the recogniser state, this keeps track of the correct node
            // even if the mouse has moved outside of the node bounds during
            // the drag operation.
            switch recognizer.state {
            case .Began:

                // Cache the clicked node
                let node = root.nodeAtPoint(rootNodePoint)
                if node != root {
                    node.position = rootNodePoint
                    draggedNode = node
                    return
                }

            case .Changed:

                // Update the cached node position
                if let draggedNode = self.draggedNode {
                    draggedNode.position = rootNodePoint
                }

            case .Ended:

                // Finally update the position and clear the cache
                if let draggedNode = self.draggedNode {
                    draggedNode.position = rootNodePoint
                    self.draggedNode = nil
                }

            default:
                return

            }
        }
    }
}

---

您是否尝试过直接将shapeNode添加到视图中，而不是首先将其添加到SKNode中？有趣的是，我认为您已经了解了一些内容。现在的问题不同了，当您这样做时，当鼠标移动到节点边界之外时，圆停止拖动。因此，之前的情况是，当鼠标快速移动时，我们将圆形节点拖动到根节点。