Unreal Snippets

This is a collection of snippets for Unreal Engine which are meant to show certain modifications of mine. The snippets are not going to work out of the box, as it may contain some of the code that is related to my project, which I'm leaving as is as it adds some clarity (such as logging), but it shouldn't be a problem to integrate it in your project, if you're familiar enough with Unreal Engine and C++.

Ability System

Ability system snippet present a way of creating generic actions using the Enhanced Input System. The actions are meant to be project specific, however there usually are some common generic actions, such as Confirm and Cancel, which are illustrated in the example, and integrated in the Gameplay Ability as default events which can be easily implemented in either C++ or Blueprints.

Setup

1. Create an Input Mapping Context (IMC) containing all the Input Actions (IA) and bound to the actual inputs.
2. Open Project Settings -> MTD -> Ability System Settings.
3. In the settings you have to assign the previously created IMC, give it a priority, and associate every IA with a Gameplay tag that will be used to identify that specific ability system generic action.
4. Implement UMTD_GameplayAbility::OnGenericActionTriggered(FGameplayTag GenericActionTag) in your custom ability to handle the generic action.
5. (Optional) Create your own UMTD_GameplayAbility::OnYOURACTIONActionTriggered() for actions specific to your own game, the same way I did with UMTD_GameplayAbility::OnConfirmActionTriggered() and UMTD_GameplayAbility::OnCancelActionTriggered(), as they're going to be used a lot.

Functionality

The generic actions are meant to be triggered (and be trigger-able) only when an ability that wants that to happen will be executing.

The MTD_GameplayAbility has a simple boolean called bActivateGenericInputActions that makes the generic actions IMC to be bound to the ability avatar's UEnhancedInputComponent while the ability is executing. It means that the IMC is unbound, hence the generic actions are non-trigger-able, after the ability ends.

While the ability that wants to use generic actions is executing all the other IAs bound to the very same keys are meant to not trigger, as the generic actions IAs are meant to consume the input as soon as possible, leaving others unaware about it.

One of the generic actions the snippet shows is Confirm. In my game that action is bound to Left Mouse Button and Space Bar, however these inputs are also associated with other IAs, such as Jump and Fire. However, as aforementioned, when the ability is executing other IAs are not going to receive any input, so in my case pressing Space Bar doesn't make the character jump, and clicking Left Mouse Button doesn't make the gun to fire, but instead it triggers UMTD_AbilitySystemComponent::OnGenericActionInput(FGameplayTag GenericActionTag), which in turn is listened by UMTD_GameplayAbility::OnGenericActionTriggered, notifying the ability about the Confirm generic action. Upon finishing the ability we unbind these delegates, making the IMC be unbound as well, so that the player can jump and fire once again.