Unity Prefabs (Unity 2018) - Overall Coverage

August 24, 2019

Unity Prefabs

Youtube - Unity Prefabs - The Complete Animated Guide | Game Dev Classroom

By: Lost Relic Games

While this tutorial on Unity prefabs is slightly behind (the version they're using in the tutorial looks to be 2018.3.5) it still covers a lot of the fundamentals of using prefabs in Unity, as well as some of the pros and cons of using them and how to use them properly. It will still be important to follow this up with more recent Unity prefab information since some concepts (like prefab variants) may already outdate some of the information in this tutorial once I understand them better.

The basic starting point is that a prefab is a container for a gameobject and all its children that you can package together into one nice, tidy, and reuseable object. You can then make several instances of this object from this one prefab.

Editing Prefabs

You can approach editing prefabs and their instances from multiple directions. You can edit the master prefab and apply those changes to every other instance of the prefab. You can edit a prefab instance, and then apply those changes back to the master prefab, and then apply those changes back to all other instances. You can also edit individual instances to have them vary from the original prefab.

You can edit the master prefab in its own prefab window now. When doing this, these changes default to being applied to all other instances as soon as they are committed to.

When editing an instance, you have options on whether to push those changes to the master or keep them separate. This can be observed with the overrides tab at the top of your prefab instance in the inspector. This lists all of the differences between your master prefab and this current instance, so you can see and decide which, if any, changes to push to the master prefab.

Nested Prefabs

You can child prefabs into other prefabs. The child prefab is still its own prefab that can be edited, and the change can be reflected in the parent nested prefab. The parent prefab now just contains that child prefab as part of its overall prefab package.

Using Prefabs

While they are generally thought to be used for objects that you will make many instances of (rightfully so), there are also benefits to having core objects of your game be prefabs as well. Objects such as your scene managers or player controllers can be prefabs to serve as sort of a backup object. If you are working on these types of objects in an isolated instance in a single scene, and somehow you lose that object or that entire scene, it will be gone forever. However, if you made these objects into prefabs, they will still exist as their own object in your assets.

Unpacking Prefabs

There are two versions of unpacking prefabs: unpack and completely unpack. Normal unpacking will just make the current prefab instance you have selected not be bound as a prefab anymore. All of its individual parts will be freed from the prefab connection. If there were any nested prefabs within this prefab, they will still be their own prefabs. It is just the overall selected prefab that is no longer a prefab. Completely unpacking however will unpack the selected prefab as well as any child nested prefabs. This ensures every single object in this selected object's hierarchy is no longer connected to a prefab in any way.

It is important to note that unpacking a prefab does not destroy your master prefab object. It simply makes the selected prefab instance not a prefab anymore, so it is no longer connected to your master prefab. The master prefab will still exist to be used in the future/will not remove your other prefab instances. This made it a useful way to make similar prefabs, by unpacking your similar prefab and editing it and making that into a new prefab (this may be somewhat outdated with Unity's new prefab variants).