Assigning Layers
Now that you have created a new layer, you have to assign the layer to one of the game objects.
In the tag manager we assigned the Player layer to be in layer 8.
Drawing only a part of the scene with the camera’s culling mask
Using the camera’s culling mask, you can selectively render objects which are in one particular layer. To do this, select the camera that should selectively render objects.
Modify the culling mask by checking or unchecking layers in the culling mask property.
Be aware that UI elements aren’t culled. Screen space canvas children do not respect the camera’s culling mask.
深度小则先画，最后大的会把小的视野挡住。相当于最后只能看到depth大的那个相机看到的。
把两个相机看到的都能显示出来
