调度队列以在 ARKit 中为 SCNNode 设置动画

Question

我在尝试定期为 ARSession 上的节点设置动画时遇到问题。我每 5 秒从 Internet 获取数据，然后使用该数据更新此节点（缩小或放大）。 我的代码如下所示：

Timer.scheduledTimer(withTimeInterval: 5, repeats: true) { timer in
    fetchDataFromServer() {
        let fetchedData = $0
        DispatchQueue.main.async {
            node1.update(fetchedData)
            node2.update(fetchedData)
            node3.update(fetchedData)
        }
        if stopCondition { timer.invalidate() }
    }
}

问题是，在调用更新时，我看到一个故障，其中相机似乎冻结了几分之一秒，并且我在控制台中看到以下消息：[Technique] World tracking performance is being affected by resource constraints [1] 更新发生正确，但如果每 5 秒我得到这些“短暂的冻结”，用户体验真的很笨拙

我也尝试过创建一个并发队列： let animationQueue = DispatchQueue(label: "animationQueue", attributes: DispatchQueue.Attributes.concurrent) 并调用animationQueue.async 而不是主队列，但问题仍然存在。 如有任何建议，我将不胜感激。

编辑：update 方法上的每个子节点看起来像这样

private func growingGeometryAnimation(newHeight height: Float) -> CAAnimation{
    // Change height
    let grow = CABasicAnimation(keyPath: "geometry.height")
    grow.toValue = height
    grow.fromValue = prevValue

    // .... and the position
    let move = CABasicAnimation(keyPath: "position.y")
    let newPosition = getNewPosition(height: height)
    move.toValue = newPosition.y + (yOffset ?? 0)

    let growGroup = CAAnimationGroup()
    growGroup.animations = [grow, move]
    growGroup.duration = 0.5
    growGroup.beginTime = CACurrentMediaTime()
    growGroup.timingFunction = CAMediaTimingFunction(
        name: kCAMediaTimingFunctionEaseInEaseOut)
    growGroup.fillMode = kCAFillModeForwards
    growGroup.isRemovedOnCompletion = false

    growGroup.delegate = self

    return growGroup
}
self.addAnimation(growingGeometryAnimation(newHeight: self.value), forKey: "bar_grow_animation")

Answer 1

要对场景进行任何更新，请使用SCNTransaction，它确保所有更改都在适当的线程上进行。

Timer.scheduledTimer(withTimeInterval: 5, repeats: true) { timer in
    fetchDataFromServer() {
        let fetchedData = $0

        SCNTransaction.begin()
        node1.update(fetchedData)
        node2.update(fetchedData)
        node3.update(fetchedData)
        SCNTransaction.commit()

        if stopCondition { timer.invalidate() }
    }
}