如何使用平移手势使用四元数在SceneKit中旋转相机

Question

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.

SCNNode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说避免使用欧拉角来避免万向节锁定.

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/

pan-gesture特别查看分支: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演示该错误的视频(请原谅视频文件的低位):https://vimeo.com/174346191

在此先感谢您的帮助!

Answer 1

我能够使用四元数来实现这一点.完整的代码在这里:ThreeSixtyPlayer.样本在这里:

    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)