我正在使用iOS SceneKit框架构建一个360度视频查看器。
我想使用UIPanGestureRecognizer来控制相机的方向。
SCNNode有几个属性可用于指定它们的旋转: rotation
(旋转矩阵)、orientation
(四元数)、eulerAngles
(每个轴的角度)。
我所读的所有内容都说要避免使用欧拉角以避免gimbal lock。
我想出于一些原因使用四元数,这里不再赘述。
我在这个问题上遇到了困难。相机控制几乎达到了我想要的效果,但是有些问题。看起来相机正在绕 Z 轴旋转,尽管我只想影响 X 和 Y 轴。
我相信问题与我的四元数乘法逻辑有关。我已经很多年没有做过任何与四元数相关的事情了 :( 我的平移手势处理程序在此处:
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
}
}
我的代码在这里开源:https://github.com/alfiehanssen/360Player/
特别是检查pan-gesture
分支:
https://github.com/alfiehanssen/360Player/tree/pan-gesture
如果你拉下来代码,我相信你需要在设备上运行它而不是模拟器。
我在这里发布了一个演示错误的视频(请原谅视频文件的低分辨率): https://vimeo.com/174346191
非常感谢您的帮助!