Layers - Official Unity Tutorial

Layers are used to indicate some functionality

across many different game objects in Unity.

For instance, layers can be used to indicate

which object should be drawn in the

scene view, should ignore raycasts,

or are invisible to the camera.

Here we have a scene with 2 orbs in it.

We can see that both orbs are on the layer Default.

If we wanted to change the layer of 1 of the orbs

we could click the Layer drop-down in the inspector

and select a new layer.

We can see that this orb is now on the

Ignore Raycast layer

and will not be hit by any raycasts that pass through it.

We also have the ability to define our own layers.

We can do so using the Tag And Layer Manager window.

To access the tag and layer manager window

either select Add Layer from the Layers drop-down

or click Edit - Project Settings - Tags And Layers.

Here we can see all of the built-in layers

as well as add our own.

Let's create an Ignored By Camera layer.

We can place our other sphere

on this newly created layer

by selecting it and choosing the New Ignored By Camera layer

from the Layers drop-down.

This sphere is now on the

Ignored By Camera layer.

The layer has no inherent functionality however

so let's modify our camera to ignore it.

In the Culling Mask property of a camera

we can select which layers are seen by the camera

and which are not.

By clicking the drop-down and

unselecting the Ignored By Camera layer

all objects on that layer will no longer

be visible to that camera.

Let's run our scene.

We can see that only a single orb appears.

The other orb, the one on the Ignored By Camera Layer

is not rendered to the screen.

We can also use layers to determine

what appears in the scene view.

By clicking on the Scene Layers drop-down

at the top right of the Unity editor

we can select and deselect layers.

Doing so will cause all objects

on those layers to disappear.