Creating a New Prefab
First, place several objects in the level that you wish to change to a prefab. Select all the objects that you require. Next, right click on one of the selected objects and choose Create Prefab.
Now, fill in a Group and Name for the new prefab. The prefab will be created in the currently selected library.
The prefab has now been created and is ready to be used in the level.
Alternatively, a prefab may be created by dragging and dropping multiple objects of choice from the Level Explorer into the Asset Browser. Objects can be picked from multiple layers.
Once assigned a custom name, the created prefab will appear listed within the Level Explorer.
Previously created prefabs that have been saved within a project's Asset directory can be used in a level by dragging and dropping them into the Viewport from the Asset Browser.
Doing so automatically creates a numbered listing for that prefab's instance in the Level Explorer; the first instance of a prefab shack_indoor, for example, will be listed as shack_indoor-1 within the Explorer. Subsequent instances will be numbered shack_indoor-2, shack_indoor-3, and so forth.
Selecting All Prefab Instances
With one more instances of a prefab selected within the Level Explorer or Viewport, right-clicking on either of the selected instances generates a context menu with the option to Select All Prefabs of Type "<prefab-name>".
Clicking this option selects all instances of the selected prefab that have been included within a level, even if these are nested in other prefabs.
Select all Prefabs of Type "Open"
In the above example, right-clicking on a prefab open brings up a context menu with the option to Select all Prefabs of Type "Open". Clicking this selects all prefabs of the same type included within the level.
Alternatively, users may select one or more instances of a prefab within the Level Explorer or Viewport, and use the prefab.select_all_instances_of_type console command to obtain the same result.
Note that the Select all Prefabs of Type "<prefab-name>" will not appear if instances of multiple different prefabs are selected, or when the selected asset is not a prefab.
Prefab Object Parameters
There are several important parameters when working with prefabs:
Auto Update All Instances
When checked, changes made to one instance of the prefab will be updated in all other instances.
Transform Pivot Mode
Lets you move the pivot of the prefab.
Any changes will be updated in other instances of the prefab as well.
A list of the objects that make up the prefab.