In the cardboard preform (Prefab), Cardboardcamera is the simplest, with only two sub-objects, one postrender, one prerender, and the camera components separately.
Cardboardprerender Script
Before the camera renders the rendering, the main task is to clear the screen, because the VR camera will not fill the entire screen in VR mode.
Cardboardpostrender Script
The effect is larger than PreRender, and at the end of the final step of the Unity rendering pipeline, the image deviation of the objects in the VR two cameras is realized. When distortion is active, it renders a pre-biased mesh as a texture. However, if the old C + + native method is activated, the task is delivered directly to the native plugin.
Because it only works on the normal camera, the overly canvas will still be filled with screens, as in non-VR.
In Sum
The prefab is already included in the Cardboardmain and is automatically generated even if it is not in the scene. If you do not use prefabricated carbboardmain, be sure to manually join the scene and set it up in the camera assembly.
P.S.
Translating English technical documents into Chinese is really far more difficult than it looks.
Reference Cardboard
Cardboardcamera Prefab Chinese Notes