2025-1102-0049 UE Unreal Engine 5 Gameplay Ability System (GAS) Crash Course

1. Section 1 Intro

2. Course Structure

3. Project Creation

• open with Rider

• editor preference

  • uncheck reinstancing
  • asset editor open location - main window

• project setting

  • change copywrite info

• Content Folder

  • CrashCourse
    • Maps
      • CCMap (new Basic map)
      • make it as default map

• import asset

  • paragon boris
  • paragon minions

• migrate assets

  • two FX

• to see the claws in the secondary fx

  • open M_ImapctSlash
    • make it Two Sided

4. Character Classes

• Source - CrashCouse - add Unreal Class

• CC_BaseCharacter (make it Abstract so can not be instantiated)
  • cpp
    • bCanEverTick = false

  // Tick and refresh bone transforms whether redered or not - for bone updates on a decdicated server  
GetMesh() -> VisibilityBasedAnimTickOption = EVisibilityBasedAnimTickOption::AlwaysTickPoseAndRefreshBones;

• create `CC_PlayerCharacter
  • remove not needed
  • .h
    • create springarm and camera
  • .cpp
    • bCanEverTick = false
    • 
    • 

5. Character Blueprint

• BP_CC_PlayerCharacter (based on CC_PlayerCharacter class, under Character Folder)
  • Mesh - Boris
  • Anim Class - Boris_AnimBlueprint
• BP_CrashGamemode
  • default pawn class - BP_CC_PlayerCharacter
• project setting
  • default gamemode
    • BP_CrashGamemode
• error debugging
  • remove sth from bp
  • bpa
    • switch devide to safe devide
      
    • remove the particle system to be played in the montage

6. Enhanced Input

• input foler
  • IMC_Movement
    • Movement Actions
      • IA_Jump
        • Space bar
      • IA_Look
        • Axis2D (Vector2D)
        • mouse XY 2D
        • Negate
          • Y
      • IA_Move
        • Axis2D (Vector2D )
        • W
          • Swizzle input axis values
          • YXZ
        • S
          • Swizzle input axis value
          • YXZ
          • negate
        • A
          • negate
        • D
          • nothing
        • 

7. Player Controller

• CC_PlayerController
  • protected
    • virtual void SetupInputComponent() override;
  • private
    • 
• .cpp
  • add imc to local player
    • 
  • bind call back function
    • 
  • implement jump and stop jumping
    • 
  • implement move and look
    • 
• create new BP_CC_PlayerController
  • add imc and ia
  • 
• update gamemode with new BP_CC_PlayerController

8. Ability Actions

9. Section 2 Intro

10. GAS Core Parts

11. Ability System Component

• make player state as owner can save the player status

• add GameplayAbility Plugin

• .build. cs

  • GameplayAbilities
  • GameplayTags
  • GameplayTags

• create CC_PlayerState

  • .h
    • public
      • construct
    • private
      • create AbilitySystemComponent
  • .cpp
    • SetNetUpdateFrequency (100. f)
    • create AbilitySystemComponent
      • replicated
      • replicationmode - mixed

• replication mode

  • depends on gameplay effects
  • full
    • to all clients
  • mixed
    • replicated to the owning client
  • minimal
    • not replicated

• .h

  • add IAbilitySystemInterface inherit
  • declare GetAbilitySystemComponent function override

• add the IAbilitySystemInterface inherit to the CC_BaseCharacter class .h

  • override GetAbilitySystemComponent function in
    • CC_PlayerCharacter
      • get PlayerState and cast to CC_PlayerState
  • initAbilityActorInfo when ready
    • for server
      • override possessedBy
    • for client
      • override OnRep_PlayerState

• owner of the AbilitySystemComponent and attributeset are different for player character

  • 

• can only init ability actor info after possesion (valid)

  • 

• create BP_CC_PlayerState

• update gamemode

12. Gameplay Abilities

• editor
  • AbilitySystem
    • Abilities
      • PlayerAbilities
        • GA_Primary
          • replication policy
            • leave it
          • instancing policy
            • instanced per actor (only 1 at given time)
            • instanced pre execution (a new 1 everytime)

13. Giving Abilities

• give ability from CC_BaseCharacter
  • create abilities array
  • give startup abilities
  • 
• call givestartup ability function on the server
  • (inside PossessedBy)
  • 
• add abilities into array in editor
  • 

14. Native Gameplay Tags

• give ability from cpp

• reason

  • if we create it in cpp, both code and editor have access
  • but if do it in editor, cpp can not get the reference directly

• create new directory GameplayTags

  • CCTags.h
  • CCTags.cpp

• add tag for GA_Primary
  • 
    

15. Activate Abilities by Tag

• give abilities in cpp

• CC_PlayerController

  • 
    

• BUT actually you can also get gameplaytag from cpp even if not define in it

  • FGameplayTag:: RequestGameplayTag ("CCTags.CCAbilities.Primary");
  • cons
    • hard coded
    • may have typo

16. Secondary and Tertiary Abilities

• create gameplay tags
  • in CCTags (. h / .cpp)
• create gameplay abilities
  • CC_PlayerController
    • .h
      • create input action
      • create function
    • .cpp
      • bind action to input
      • implement function
        • activate with tags
• editor

  • create abilities

    • GA_

  • bind tags in abilities

  • implement abilities logic inside

  • create input actions

    • IA_

  • bind to IMC

  • bind inside CC_PlayerController

  • add abilities to startup abilities in CC_PlayerCharacter

17. Base Ability Class

• .h

public:  
  
    UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Crash|Debug")  
    bool bDrawDebug = false;

• make GA derived from new CC_GameplayAbility
• branch with DrawDebug bool

18. Play Montage and Wait

• PlayMontageAndWait

• net synced because net execution policy - local predicted

  • client will see it
  • and server will get it
  • do not need RPC

• instancing policy

  • instanced per actor

• flipflop with Primary_B_Montage

• create shorter animations

• create montage for them

  • use correct slot - Upperbody
  • blend time
    • in .05
    • out .25

• if want hold to trigger

  • CC_PlayerController - ETriggerEvent::Triggered

19. Section 3 Intro

20. Gameplay Events

• create AN_SendEventToActor
  • override Received Notify
  • create gameplay tag
    • CCTags. Events. Player. Primary
  • send gameplay event to actor
    • make event tag as variable (public)
• add event tag inside anim montage
• inside GA_Primary
  • wait gameplay event

21. Enemy Class

• create CC_EnemyCharacter

  • bCanEverTick = false
    

• create AbilitySystemComponent variable

  • create
  • SetIsReplicated = true
  • SetReplicationMode = Minimal

• override GetAbilitySystemComponent function

  • return AbilitySystemComponent

• InitAbilityActorInfo in Beginplay

  • GiveStartupAbilities

• in editor

  • create BP_Enemy_Melee
  • BP_Enemey_Ranged
    • ranged core dawn
    • create animation bp
      • ABP_Enemy_Ranged
        • get speed
          • 
        • a better way
          • override Blueprint Thread Safe Update Animation
            • property access
            • 
    • animgraph
      • idletorun_a_combat
        
    • set anim class in bp

• BP_Enemy_Melee

  • mesh
    • minion_melee
  • create similar abp
    • but seems do not have same blendspace...
  • assign to BP_Enemy_Melee

22. Custom Ability System Component

• create CC_AbilitySystemComponent
  

23. Auto Activated Abilities

• override OnGiveAbility function in CC_AbilitySystemComponent

24. Hit React Ability

• add tags in cpp
  • CCTags.Events.Enemy.HitReact
• create CC_HitReact class
  • 
• create GA_CC_HitReact
  • 
• create BP_CC_EnemyBase
  • make BP enemy inherit from it

25. Overlap Test

• send event from GA_Primary to detect overlap
• change default pawn object type collision set
  • change visibility channel from ignore to block
• create a cpp class to let GA_Primary to inherit
  • 
    

• reparent GA_Primary

26. Hit React Gameplay Event

• send event from GA_Primary
• CC_Primary
  • encapsule
    • DrawHitBoxOverlapDebugs
  • refactory HitBoxOverlapTest function
  • create SendHitReactEventToActors function

27. Calculating Hit Direction

• put debug string function to cpp
• create utils cpp
  • 
• create direction calculation function
  • EHitDirection UCC_BlueprintLibrary::GetHitDirection(const FVector& TargetForward, const FVector& ToInstigator)

28. Hit React Montages

• create hit montage
• play hit montage
• create child bp based on GA_CC_HitReact
  • override montage to play
• Montage jump to section

29. Primary Attack Particles

• add new notify track in montage
• add notify - play niagara particle effect
• choose correct niagara system

30. Section 4 Intro

31. Attribute Set

• CC_AttribteSet
• define macro ATTRIBUTE_ACCESSORS
• create attribute data - health

32. Adding the Attribute Set

• add attributeset to playerstate and enemy character

33. Initialize Attributes Gameplay Effect

• create GE_InitializeAttributes
• override all values to 100 with ge modifiers
• in base character class
  • create InitializeAttributeEffect GE
  • create InitalizeAttributes const function
• apply for player character and enemy character
  • player character on server, so PossessedBy
  • enemy character also on server, so BeginPlay

34. Attribute Widget Component

• create CC_WidgetComponent
  • InitAbilitySystemData function
• create OnASCInitialized delegate to broadcast on server and client after initialized
  • OnASCInitialized.Broadcast(GetAbilitySystemComponent(), GetAttributeSet());
• ADD UMG in build. cs

35. Post Gameplay Effect Execute

• know when ge is initialized, broadcast when initialized

36. Attribute Widget

• create CC_AttributeWidget to show attribute

37. Attribute Widget Blueprints