我正在使用iOS SceneKit框架构建360视频查看器。
我想使用UIPanGestureRecognizer来控制相机的方向。
SCNNodes有几个属性我们可以用来指定它们的旋转：rotation（旋转矩阵），orientation（四元数），eulerAngles（每个轴角度）。
我读过的所有内容都是为了避免使用欧拉角来避免使用gimbal lock。
我想使用四元数有几个原因，我不会在这里讨论。
我无法让它正常工作。相机控制几乎就是我想要的地方，但有些不对劲。尽管我试图仅影响X和Y轴，但看起来好像相机正绕着Z轴旋转。
我相信这个问题与我的四元数乘法逻辑有关。多年来我没有做过与四元数相关的任何事情:(我的平移手势处理程序在这里：
func didPan(recognizer: UIPanGestureRecognizer)
{
switch recognizer.state
{
case .Began:
self.previousPanTranslation = .zero
case .Changed:
guard let previous = self.previousPanTranslation else
{
assertionFailure("Attempt to unwrap previous pan translation failed.")
return
}
// Calculate how much translation occurred between this step and the previous step
let translation = recognizer.translationInView(recognizer.view)
let translationDelta = CGPoint(x: translation.x - previous.x, y: translation.y - previous.y)
// Use the pan translation along the x axis to adjust the camera's rotation about the y axis.
let yScalar = Float(translationDelta.x / self.view.bounds.size.width)
let yRadians = yScalar * self.dynamicType.MaxPanGestureRotation
// Use the pan translation along the y axis to adjust the camera's rotation about the x axis.
let xScalar = Float(translationDelta.y / self.view.bounds.size.height)
let xRadians = xScalar * self.dynamicType.MaxPanGestureRotation
// Use the radian values to construct quaternions
let x = GLKQuaternionMakeWithAngleAndAxis(xRadians, 1, 0, 0)
let y = GLKQuaternionMakeWithAngleAndAxis(yRadians, 0, 1, 0)
let z = GLKQuaternionMakeWithAngleAndAxis(0, 0, 0, 1)
let combination = GLKQuaternionMultiply(z, GLKQuaternionMultiply(y, x))
// Multiply the quaternions to obtain an updated orientation
let scnOrientation = self.cameraNode.orientation
let glkOrientation = GLKQuaternionMake(scnOrientation.x, scnOrientation.y, scnOrientation.z, scnOrientation.w)
let q = GLKQuaternionMultiply(combination, glkOrientation)
// And finally set the current orientation to the updated orientation
self.cameraNode.orientation = SCNQuaternion(x: q.x, y: q.y, z: q.z, w: q.w)
self.previousPanTranslation = translation
case .Ended, .Cancelled, .Failed:
self.previousPanTranslation = nil
case .Possible:
break
}
}
我的代码是开源的：https://github.com/alfiehanssen/360Player/
查看pan-gesture分支：https://github.com/alfiehanssen/360Player/tree/pan-gesture
如果你把代码拉下来，我相信你必须在设备而不是模拟器上运行它。
我在这里发布了一个视频来演示该错误（请原谅视频文件的低红色）：qazxsw poi
在此先感谢您的帮助！
我能够使用四元数来实现这一点。完整的代码在这里：https://vimeo.com/174346191。样本在这里：
ThreeSixtyPlayer
对不起，这使用 let orientation = cameraNode.orientation
// Use the pan translation along the x axis to adjust the camera's rotation about the y axis (side to side navigation).
let yScalar = Float(translationDelta.x / translationBounds.size.width)
let yRadians = yScalar * maxRotation
// Use the pan translation along the y axis to adjust the camera's rotation about the x axis (up and down navigation).
let xScalar = Float(translationDelta.y / translationBounds.size.height)
let xRadians = xScalar * maxRotation
// Represent the orientation as a GLKQuaternion
var glQuaternion = GLKQuaternionMake(orientation.x, orientation.y, orientation.z, orientation.w)
// Perform up and down rotations around *CAMERA* X axis (note the order of multiplication)
let xMultiplier = GLKQuaternionMakeWithAngleAndAxis(xRadians, 1, 0, 0)
glQuaternion = GLKQuaternionMultiply(glQuaternion, xMultiplier)
// Perform side to side rotations around *WORLD* Y axis (note the order of multiplication, different from above)
let yMultiplier = GLKQuaternionMakeWithAngleAndAxis(yRadians, 0, 1, 0)
glQuaternion = GLKQuaternionMultiply(yMultiplier, glQuaternion)
cameraNode.orientation = SCNQuaternion(x: glQuaternion.x, y: glQuaternion.y, z: glQuaternion.z, w: glQuaternion.w)
而不是四元数，但适合我的使用。我将它应用到我的根最几何的几何节点容器（“rotContainer”）而不是相机，但一个简短的测试似乎表明它也适用于相机使用。
SCNVector4bbedit的解决方案与func panGesture(sender: UIPanGestureRecognizer) {
let translation = sender.translationInView(sender.view!)
let pan_x = Float(translation.x)
let pan_y = Float(-translation.y)
let anglePan = sqrt(pow(pan_x,2)+pow(pan_y,2))*(Float)(M_PI)/180.0
var rotationVector = SCNVector4()
rotationVector.x = -pan_y
rotationVector.y = pan_x
rotationVector.z = 0
rotationVector.w = anglePan
rotContainer.rotation = rotationVector
if(sender.state == UIGestureRecognizerState.Ended) {
let currentPivot = rotContainer.pivot
let changePivot = SCNMatrix4Invert(rotContainer.transform)
rotContainer.pivot = SCNMatrix4Mult(changePivot, currentPivot)
rotContainer.transform = SCNMatrix4Identity
}
}
结合得很好。按照链接答案中的建议设置摄像机，然后使用bbedit的想法旋转“轨道”节点。我修改了他的代码的Swift 4版本的代码，它确实有效：
Rotating a camera on an orbit