add canvas check if the event system is added, add holo input module to event system;
scale the canvas；
set canvas to world-space;
set canvas camera to hololens camera(!!!!)
(
here, the problem showed.: you are not able to change the camera of the canvas
with a warning telling you that the camera will be updated to uiraycast camera?
why？what is uiraycast camera?
i didn't get the answer by searching on google
well, the solution is to click on the inputmanager, and you will see the script named focus manager on it.
and then , you will see a uiraycast camera open to set.
set it to main camera.
and run, the camera of the canvas will be automatedly updated to it
)
