Read-only value that can be used to determine if the VR device is active.
When true, Unity is accepting input from the HMD and rendering to the HMD's display(s). This can become false if a device is disconnected, a device could not be intialized (see VRSettings.LoadDeviceByName), or VRSettings.enabled is set to false.
VRの出力は自動的にメインディスプレイにミラーリングされます（適用可能な場合は）。これは VRSettings.showDeviceView で制御できます。
The main window is still controlled by Screen and related APIs.