Scene Graph is Now Available as an Experimental Feature in UEFN

The previously announced Scene Graph is now available to try in UEFN as an Experimental feature! An Experimental release gives you a chance to try out the functionality while it’s still in development. 

New to scene graphs? Scene graphs provide a unified structure for connecting all the objects within an island, making it faster and easier to create, manipulate, and iterate on elements, gameplay, and level design in your islands. They are particularly useful when working on environments populated with a large amount of content (or game types featuring more complex interactions such as platformers, Metroidvanias, and deathruns). If you’re looking for a way to build richer, deeper Fortnite islands in the future, this feature is for you.

We want to put exciting new features in your hands with a view to improving them based on your feedback before final release. In the Experimental release of the Scene Graph feature, you’ll be able to try out an early version, but you won’t be able to publish islands created using it until the Early Access release. The timing of the release is still to be determined, and we'll share more details in the future. However, this Experimental release gives you the opportunity to learn an entirely new core feature we think is critical long-term for our development ecosystem and the metaverse.


 

Breaking Down Scene Graph

There are three key concepts within Scene Graph: Components, Entities, and Prefabs.  These will enable you to create and structure your content in a way that’s easy to organize and understand. You’ll also be able to quickly reuse the same or similar content in different parts of your island, with the ability to make changes to all instances of this content globally or edit each one individually.
 

Components

• Components include data and logic for your game.
• They can be as simple as a transform or mesh (or purely logical, like a Verse script).

 

Entities

• Entities are containers for Components.
  • For example, an Entity could be an object such as a torch that contains all of the Components that make up the torch, including VFX, sound effects, and lighting.
• Entities have hierarchy, allowing you to create sub-objects that are tied to a parent. The parenting represents object lifetime: if the parent is removed from the scene, so are the sub-objects.
• You can remove an Entity from a scene by disposing it. This will free up memory if it’s no longer needed. Or, you can unset its parent which removes it from the scene, but lets you return it to the scene by resetting the parent.

 

Prefabs

• Prefabs are multiple Entities and their Components grouped together in a class.
• This is the highest level construct in the Scene Graph.
• At the Verse level, a Prefab is a class that inherits from Entity which contains all of the Entities you have added to the Prefab.
• Prefabs can be spawned from Verse, making it easy to make multiple copies.
• Disposing or unsetting its parent removes the entire Prefab from the scene; resetting the parent brings back the entire Prefab; and setting a new parent moves the entire Prefab under that new Entity.
• Changes can be made and applied globally to all instances of a Prefab, or individual Prefabs can be modified without impacting other instances.
• You can nest Prefabs inside of other Prefabs.
• Prefabs can be created and modified using the new Prefab Editor or Verse.

 
Check out our Inside UEFN Scene Graph talk from GDC 2024 to find out more about Scene Graph, and see how concepts like Prefabs make creating complex gameplay and content-rich game worlds easier than ever with UEFN.
   

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Want to learn even more about Scene Graph? Head over to the new Scene Graph documentation and jump into the new Prefabs Template in the editor for a hands-on example!
 

Scene Graph FAQ

What is a Scene Graph?

The UEFN Scene Graph is a unified structure that connects all objects within a scene. This enables you to reason about the scene and code can walk the graph to perform operations related to objects. It functions similarly to the Document Object Model (DOM) in web programming. In Unreal Engine, Actors and Actor Components currently serve the role of the Scene Graph.
 

How will this impact the existing device-based workflows in UEFN?

You will still be able to author gameplay using Devices in UEFN, and both the Scene Graph and Devices can be used within the same project. Devices provide you with building blocks for authoring gameplay that come with predefined parameters that you can adjust and combine with other Devices and Verse to create complex interactions in your Islands. The Scene Graph enables you to construct prefabs that can combine Verse-authored gameplay and other component types into reusable bundles of content, these can be similar to existing devices but easier to replicate and edit, and can also extend to a broader range of content and functionality than devices. We are developing a bridge component to enable limited interoperability between Devices and the Scene Graph, helping creators integrate existing gameplay into their scene graph.
 

What does Scene Graph being an ‘Experimental feature’ mean?

The Scene Graph feature is in an Experimental state, so you can try it out, provide feedback, and see what we are planning. You cannot publish a project that uses Scene Graph at this time. Keep in mind backward compatibility for assets created at the experimental stage is not guaranteed. The APIs for these features may change, and we may remove entire Experimental features or specific functionality at our discretion.
 

Why can’t I publish projects that use the Scene Graph currently?

Publishing is disabled for projects that use experimental features. Once a feature is fully released or made available as Early Access, you will be able to publish projects using that feature.
 

What are the known limitations of the Scene Graph with the Experimental release?

You can find the list of known issues for this experimental feature here. If you have feedback or encounter issues not listed, please report them in the forum.
 

Where can I find more information?

You can watch the ‘Inside UEFN Scene Graph | GDC 2024’ tech talk on the Unreal Engine YouTube channel or visit the new Scene Graph documentation.