OpenVR 下，獲取裝置位置的方法有兩個：WaitGetPoses 和 GetDeviceToAbsoluteTrackingPose。 WaitGetPoses： 會阻塞程式執行，直到底層獲取到新的裝置姿態位置才可以返回。 GetDeviceToAbsoluteTrackingPose： 則時通過傳遞預計算裝置的位置，來預測新的裝置位置。

兩個函式都可以獲取到裝置位置，但作用不同。WaitGetPoses：不僅獲取裝置位置，同時也負責同步、重新整理等工作，如果不呼叫該函式，即使submit了左右眼的紋理資料，Vive也無法現實提交的資料。而GetDeviceToAbsoluteTrackingPose，是通過傳遞時間引數，進行預計算，當前裝置的預測位置，這樣更能對當前的渲染系統提供準確的裝置資訊。

• WaitGetPoses:更新裝置的姿態資訊

  /** Scene applications should call this function to get poses to render with (and optionally poses predicted an additional frame out to use for gameplay).
  * This function will block until "running start" milliseconds before the start of the frame, and should be called at the last moment before needing to
  * start rendering.
  *
  * Return codes:
  *   - IsNotSceneApplication (make sure to call VR_Init with VRApplicaiton_Scene)
  *   - DoNotHaveFocus (some other app has taken focus - this will throttle the call to 10hz to reduce the impact on that app)
  */
  virtual EVRCompositorError WaitGetPoses( VR_ARRAY_COUNT(unRenderPoseArrayCount) TrackedDevicePose_t* pRenderPoseArray, uint32_t unRenderPoseArrayCount,
  VR_ARRAY_COUNT(unGamePoseArrayCount) TrackedDevicePose_t* pGamePoseArray, uint32_t unGamePoseArrayCount ) = 0;
   
  

• GetDeviceToAbsoluteTrackingPose

  /** The pose that the tracker thinks that the HMD will be in at the specified number of seconds into the 
      * future. Pass 0 to get the state at the instant the method is called. Most of the time the application should
      * calculate the time until the photons will be emitted from the display and pass that time into the method.
      *
      * This is roughly analogous to the inverse of the view matrix in most applications, though 
      * many games will need to do some additional rotation or translation on top of the rotation
      * and translation provided by the head pose.
      *
      * For devices where bPoseIsValid is true the application can use the pose to position the device
      * in question. The provided array can be any size up to k_unMaxTrackedDeviceCount. 
      *
      * Seated experiences should call this method with TrackingUniverseSeated and receive poses relative
      * to the seated zero pose. Standing experiences should call this method with TrackingUniverseStanding 
      * and receive poses relative to the Chaperone Play Area. TrackingUniverseRawAndUncalibrated should 
      * probably not be used unless the application is the Chaperone calibration tool itself, but will provide
      * poses relative to the hardware-specific coordinate system in the driver.
      */
      virtual void GetDeviceToAbsoluteTrackingPose( ETrackingUniverseOrigin eOrigin, float fPredictedSecondsToPhotonsFromNow, VR_ARRAY_COUNT(unTrackedDevicePoseArrayCount) TrackedDevicePose_t *pTrackedDevicePoseArray, uint32_t unTrackedDevicePoseArrayCount ) = 0;