Gameplay Targeting System
The Gameplay Targeting System is a way to create data-driven targeting requests. It expands on the Gameplay Ability System Plugin, but could be used outside of the feature.
You can enable the Targeting System from the Editor by navigating to Edit > Plugins > Gameplay > Gameplay Abilities > Targeting System.
Setting up the Targeting System Plugin.
Data and Design
The Targeting System uses a Targeting Preset. This Targeting Preset is a data asset that defines a set of Targeting Tasks that are run from top to bottom for an executed targeting request.
The TP_Knockback_Pistol is a targeting preset set up with a Trace targeting task and Filter by the Actor class targeting task.
A feature of targeting presets is that each task supports inline property editing. You can define reusable targeting tasks and presets that set up how the tasks behave without defining a UAsset for each one.
Between the two images above. The Trace Types and the Required Actor Classes are different. This is done in the same targeting preset without having to pick different targeting tasks.* *
TargetingTask
A Targeting Task is a small unit operation meant to perform a desired action. Targeting Tasks can be generally thought about in 3 categories, Selection, Filtering,and Sorting.
Targeting tasks have Blueprint support. Depending on how you engineered your tasks, it can be as simple as setting up Class default properties to handling Blueprint callable events.
Example: The Knockback Pistol Trace task is set up with two overridable events to calculate the source location and the direction of the trace. In this example, if you look at the Blueprint code you'll see it gets the pawn and calls a function to get the camera location and camera direction.
Immediate Targeting Requests
Immediate Targeting Requests are performed by calling the UTargetingSubsystem::ExecuteTargetingRequest function. The Targeting Request is based on a UTargetingPreset Object and is executed immediately, therefore blocking the Game Thread until it is completed.
Async Targeting Requests
Async Targeting Requests are performed by calling the UTargetingSubsystem::StartAsyncTargetingRequest function. The Targeting request is based on a UTargetingPreset Object and starts immediately, however, it may not block the Game Thread until it is completed.
These requests are useful when a Targeting Task may need to wait for a slow operation (for example, waiting for the server to authenticate a target) or for a gameplay event to occur before targeting can be completed.
All Targeting Tasks defined in the GameplayTargetingSystem Plugin will provide implementations for both Immediate and Asynchronous targeting requests, however, the game code is not enforced to implement both if the game does not use the async functionality.
Async Action - Perform Targeting / Perform Filtering
UAsyncAction_PerformTargeting provides generic Blueprint support for starting an Async Targeting Request or Filtering Action.
Debugging
For a complete list of debug console commands and descriptions, see the Gameplay Targeting Debugging documentation.
Developer Reference
For an in-depth Engineering reference guide, see the Gameplay Targeting Plugin Reference documentation.