SceneKit 中声明的 func hitTest 导致 Playground 崩溃

Question

我在操场上创建一个场景并使用 hitTest (func hitTest(_ point: CGPoint, options: [SCNHitTestOption : Any]? = nil) -> [SCNHitTestResult]) 函数来确定其中一个节点是否已被触摸，但只有当节点被触摸时，它才会导致操场上的模拟器崩溃。使用 xcode 的 iOS 项目上的相同代码不会发生这种情况。

func panGesture(sender: UIPanGestureRecognizer) {
    sender.view

    let translation = sender.translation(in: sender.view!)

    var newAngleX = (Float)(translation.y)*(Float)(M_PI)/180.0
    newAngleX += currentXAngle
    var newAngleY = (Float)(translation.x)*(Float)(M_PI)/180.0
    newAngleY += currentYAngle

    if (sender.numberOfTouches>0){

        var point = sender.location(in: self)

        print(point)

        let hit = self.hitTest(point, options: nil)

        let node = hit.first?.node

        node?.eulerAngles.x = newAngleX
        node?.eulerAngles.y = newAngleY

        if(sender.state == UIGestureRecognizerState.ended) {
            currentXAngle = newAngleX
            currentYAngle = newAngleY
        }

    }

}

Answer 1

这在 Playground 中运行得非常、非常、非常慢……但也许还有其他事情发生。无论如何，如果你用这个替换你的func panGesture(sender: UIPanGestureRecognizer)，它至少应该让你在 Playground 中运行它而不会崩溃。

func panGesture(sender: UIPanGestureRecognizer) {
    sender.view

    let translation = sender.translation(in: sender.view!)

    var newAngleX = (Float)(translation.y)*(Float)(M_PI)/180.0
    newAngleX += currentXAngle
    var newAngleY = (Float)(translation.x)*(Float)(M_PI)/180.0
    newAngleY += currentYAngle

    let point = sender.location(in: self)
    print(point)

    // important
    guard let hit = self.hitTest(point, options: nil) as? [SCNHitTestResult] else { return }

    // and, don't go in here if hit.count == 0, because it won't have a .first
    if (sender.numberOfTouches > 0 && hit.count > 0){

        let node = hit.first?.node

        node?.eulerAngles.x = newAngleX
        node?.eulerAngles.y = newAngleY

        if(sender.state == UIGestureRecognizerState.ended) {
            currentXAngle = newAngleX
            currentYAngle = newAngleY
        }

    }

}