1️⃣ Overview
Creating a user interface can often be quite cumbersome, particularly in the case of a Heads-Up Display (HUD), which typically requires the presentation of numerous elements.
As game systems become progressively intricate, HUDs tend to grow unwieldy, containing a plethora of interrelated content.
Many UI elements dynamically hide or display different widget content based on the gaming context. The UI Extension System is designed to assist you in:
- Arranging a series of placeholders (extension points) marked with GameplayTags within the HUD
- Injecting various UI widgets dynamically into different placeholders through game code (adding UI to extension points) and removing them from specific extension points, thus facilitating modular management and performance optimization.
2️⃣ Usage
- Placing extension Points
Identify the widget you wish to extend during gameplay (generally larger UI elements such as HUDs or inventory panels) and add the GUIS_GameUIExtensionPointWidget in an appropriate location, configuring its dimensions and position.
You will also need to associate it with a GameplayTag.
- Dynamically Registering Widgets to extension Points
At suitable moments within the game, invoke the aforementioned API to inject UI into the extension points. For instance, only when there is an interactive object nearby will the “Interaction Box” widget be dynamically injected.
- Unregistering from extension Points
Upon registering a widget, store the returned value (ExtensionHandle) in a secure location.
When the UI is no longer required, you can unregister it by calling the above API and passing the ExtensionHandle, thereby removing the widget.
3️⃣ Case Study
The image below depicts my HUD, which appears stark and empty, occupied solely by a few placeholders.
Different systems can share this identical HUD layout, yet inject distinct content:
Movement System
Combat System
4️⃣ Advanced Usage
Extension points support exact or partial tag matching and may restrict allowed data classes. For context-specific registrations, the extension and point must use the matching ContextObject; choose the correct context for each local player.
Use the world's GUIS_ExtensionSubsystem and Register Extension (Widget) or Register Extension (Widget For Context) to register, then retain the ExtensionHandle and call UnregisterExtension when the feature ends. If you register a point yourself, retain and unregister its handle too. If content does not appear, check tag matching, context, allowed data classes, and handle lifetime.