In a previous article we saw a very premature version of the physics prediction system that now bundles with Unreal Engine. Now, in Unreal Engine 5.4 the system has matured a lot and in todays article we will do a hands-on together. Introduction Predicting and correcting physics is one of the most complicated topics when it comes to network prediction. The nature of the complexity comes by the fact that if we hit a chain of physics objects on the client, we’d expect all the physics to react instantaneously, without having to wait for the server. But not only that, these physics objects should ..read more

Unreal Engine introduced Mover 2.0 in 5.4, this post showcases my first (second) impressions and an overview of the system. Introduction Epic Games recently introduced a new and experimental Movement Component in 5.4, called Mover, so… let’s take a look. In order to activate the feature, open Edit and within Plugins windows, turn on the following: How does it work? The following video I’ve recorded showcases the state of the system at the release date of the Plugin during UE 5.4: Note: At the time of writing, Mover 2.0 is only obtainable through the git version of the engine, branch 5.4 or u ..read more

Hello and happy new year! Many of you asked me how I measured the accuracy in my network clock article. This technique can be generalized to infinite use cases, so I decided to generalize it and write about it in this small article. So I hope you like it and find it useful. Overview This article explains how to access the server instance from a client in PIE (Play in Editor), thus, easing logging of value discrepancy between server and client. This technique has served me in the past to debug synced variables. In essence, expect something as follows: LogEntry: Client Stamina: 29.25 | Server ..read more

Hello! In this post we’ll learn together how to Lazy Load the Ability System Component in our multiplayer games to reduce memory usage! Introduction The Ability System Component (ASC) can be a bit resource-intensive, especially when dealing with World Actors that require it, like Damageables. If our world is populated with such Actors, their memory footprint can become noticeable. Taking a cue from Epic and the insights shared by Tranek in the excellent GASDocumentation, Fortnite adopts a smart approach. They lazily load their ASCs in their World Actors just when they’re needed, dodging the me ..read more

Hello! In this post we’ll expose a very simple pattern you can use to replicate any long stateful sound or animation. In addition, we’ll learn about some caveats when it comes to replication order guarantees. Introduction There are times when we want to replicate a long animation and still have it playing in the correct timeframe when a client joins. While the Gameplay Ability System does this with the PlayMontageAndWait node, GAS is not always appropriate for all of our use cases. The same problem also occurs with music or other animated elements, such as an elevator. In all the cases, we wan ..read more

Unreal Engine introduced Physics prediction in 5.3, this post showcases a little demo project using it. Introduction Wow! I didn’t see that coming! Epic Games introduced an experimental Physics prediction feature in 5.3, so… let’s take a look. In order to activate the feature, open Project Settings and within the Physics tab, turn on Enable Physics Prediction. There are other settings you might want to explore! How does it work? The following video I’ve recorded showcases the state of the system at the release date of UE 5.3 Preview. Conclusion Thanks for watching! Hopefully you are as hyped ..read more

This article is a collaboration with WizardCell and on it, you’ll learn how DORM_Initial works and why you should be careful with it. Introduction If we read the description of the DORM_Initial dormancy setting, we see what follows: This actor is initially dormant for all connection if it was placed in map. Which made me understand that this setting would work like DORM_DormantAll just with a couple extra optimizations. But it isn’t the case, let’s see what are the implications of using this setting. DORM_DormantAll versus DORM_Initial When an Actor becomes relevant to a connection, all the ..read more

In this article we’ll learn how to stream big quantities of data realiably from and to your clients in Unreal Engine. Introduction As we saw in a previous article, Unreal Engine diposes of different tools to send data, such as RPCs and replicated variables. As we’ve studied in the past, each of them have a different purpose: Replicated variables: These variables should be set in the server and they will replicate down to the relevant clients following the defined replication condition. Incoming relevant connections will also receive the state hold by the replicated variables (if applicable ..read more

In this article we’ll learn how to implement a killcam. Introduction Instant replays (or Killcams) can help the player understand how their character died during a game. They can be very useful in competitive scenarios to visualize the position of the instigator at the moment of your death, so they will play an important role in your game design if you decide to bring them in. I’ve always wondered how to implement them properly in Unreal Engine, however, the DemoNetDriver documentation was scarce and duplicating the whole UWorld, like Unreal Tournament did, never convinced me. For that reason ..read more

In this article we’ll learn how to achieve a low-bandwidth and efficient procedural generation for big multiplayer worlds. Introduction Procedural generation is a concept that has been well explored in a handful of games, as this type of content creation can provide replayability if designed properly. In this post we are not going to tackle generation algorithms, as that is very game-specific, but we are going to explain how to make your procedural generation multiplayer friendly in Unreal Engine. Most of these concepts have been explained to me by a very good friend of mine, Zlo, for that rea ..read more