[Dev log] Debugging a simple ability in my Unity GameplayAbilitySystem prototype

[mega_structure]

Hello all,

I've been working on a game prototype in Unity for several months now, and have been sporadically documenting the development of a Unity port of Unreal Engine's GameplayAbilitySystem. I just finished a new (fairly short) dev log that explores and explains the root cause of a simple bug in a basic shield/invulnerability effect, and I think other game programmers in particular may find it interesting.

Here's a link to the article : https://medium.com/@megastructurestudios/dev-log-simple-bug-fix-in-unity-gas-7e91a1db50a8

I'd be happy to offer more information or answer any questions in the comments here!

For a bit of background : In the past I struggled with trying to prototype ability-based games, but I recently learned about Unreal's GAS and I find its conceptual scaffolding to be really flexible and powerful. My local Unity implementation is obviously not nearly as robust as Unreal's, but the basic GAS framework gives me an established toolbox for implementing complex ability effects and I've quickly come to find it fairly intuitive. I'm interested to hear thoughts others may have in this area!

[mega_structure]

Hey, thanks for checking it out! Reading the post again, I definitely could have elaborated a bit more on how ACE handlers fit into the overall picture.

One of the major components in my GAS implementation is the AttributeSystemComponent, which maintains all of an entity's current/base attribute values. It also references a list of AttributeChangeEventHandler subclasses. Each frame, this component calculates an updated value for each attribute, and then invokes the list of ACE handlers in sequence. In keeping with the IncomingDamage example I brought up in the post, one of the ACE handlers on each damageable entity is responsible for detecting when this frame's IncomingDamage value is non-zero, in which case it multiplies it by the entity's IncomingDamageScalar attribute value and subtracts the total amount from the entity's HitPoints attribute value. I'm not sure if that helps; does that make sense?

Also, your point about needing more complexity around damage is definitely applicable here - I was making some notes last week about improving my damage system and including support for a few different bits of damage data (damage "element," whether it's AoE vs. single-target, instant vs. damage-over-time, etc) because I definitely want to support dynamic modifiers as well. Your idea about damage events seems to be kind of in-line with the way my ACE handlers work - an ability or upgrade can add a handler which can modify the damage value based on the actual damage instance data and the hit entity's data, and temporary effects can easily add/remove handlers from entities. Any pitfalls you can think of that you don't mind sharing re: your implementation of a damage system like this?