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What is UEFN's Experimental Feature "Scene Graph"?
Epic's latest livestream was dedicated to the new, experimental feature, Scene Graph. Here's our notes and key takeaways.
Scene Graph may bring a new standard for UEFN and the Metaverse, but why?
You may have spotted the term “Scene Graph” across Discord servers, patch notes and GDC talks over the past few months. This new tech is bringing a lot of buzz with it as it is introduced into the UEFN engine and for good reason. The designers are challenged with foreseeing the future of game design as well as the needs of the Metaverse, and develop a tool to make this new future a reality.
Epic recently live streamed a demo with some information on what this will mean for Island creators with a few exciting tidbits hidden in the questions and answers. Here are our thoughts!
What is “Scene Graph”?
A Scene Graph is a connection of all the renderable things in our game world. In UEFN, it will be at the core level of Verse and will become the building blocks of designing levels and islands in the future. The true power of this feature is the ability to run scripts and communicate to our assets in the level at run time, as well as create functions and push gameplay mechanics.
An example discussed in the live stream mentions running a script to collect all the buildings in the scene and then setting them on fire, presumably with scriptable material functions, effects and parameter collections.
Prefabs
The demo showcases the “Prefab” system that Scene Graph uses. This system allows for easy and intuitive hierarchies to be built, directly from the outliner window. These hierarchies use a parent child relationship so children will naturally inherit the transforms of their parents as well as other properties.
The example provided is a lamppost which has a light mesh and light actor as its children. The light mesh has a swinging animation applied to it, which the light actor automatically inherits because it is a child of the mesh, but the lamppost itself, stays rigid as it is the parent object of them all.
This may seem simple or trivial, but when paired with Verse code, will add a lot of complexity and potential to this system.
Workflow
We believe this tool will bring with it a huge workflow and productivity boost to artists working on their islands. The prefab system uses the "one file per actors” system which allows multiple developers to work in the same scene together and not override each others work. large teams will be able to piece together a catalog of prefabs and environments easily and importantly, simultaneously.
These prefabs also have an “Override” system which flags only the properties which have been edited from the original prefab. This will allow for potentially hundreds of variants with nested prefabs, to all receive updates to any property which have been left untouched. Anyone who has had to make large, sweeping changes from feedback and art direction knows how much of a time saver one click updates could make your workflow.
Optimization
Currently, as the tool is still in the experimental stages, its not going to give any performance boosts to your islands. However, as the tool matures and more work goes into the live release, there will be optimization improvements made to the Perfabs when used in your scene.
Improvements to draw calls through automatic instantiation where possible, and it was even mentioned that one of the goals, is to out perform current tools and islands.
We think this is SUPER helpful to creators as we often hear islands can be blocked due to the memory limitation for publishing. This could go a long way to opening the door for larger experiences.