GameplayAbilitySystem

GAS是Epic提供的一套技能解决方案，使用时需要在plugin启用Gameplay Abilities插件。

Ability & Input

• 处理输入的类需要实现IAbilitySystemInterface的接口，并且创建AbilitySystemComponent

//创建AbilitySystemComponent组件 
AbilitySystemComponent = CreateDefaultSubobject(TEXT("AbilitySystemComponent")); 
//重写该方法
UAbilitySystemComponent* AGasLearningCharacter::GetAbilitySystemComponent() const { return AbilitySystemComponent; }

• GAS依靠Key相同这一默认约定，将输入与技能ID做了绑定。

/** *key 要与项目input的设置一致，才能刚在gas里绑定 */ 
UENUM(BlueprintType) enum class EGASAbilityInputID : uint8 {
//0 None None UMETA(DisplayName = "None"),
//1 Jump Jump UMETA(DisplayName = "Jump"),
//2 Sprint Sprint UMETA(DisplalyName = "Sprint")
}; 
void Character::SetupPlayerInputComponent(class UInputComponent* PlayerInputComponent)
//绑定输入与释放的技能(通过枚举的key和Input的key一一对应) 
AbilitySystemComponent->BindAbilityActivationToInputComponent(
  PlayerInputComponent,
  FGameplayAbilityInputBinds(
    FString(),/**ConfirmTargetCommand*/
    FString(),/**CancelTargetCommand*/
    FString(TEXT("EGASAbilityInputID")),/**EnumName,即上面定义的枚举*/     
    static_cast(EGASAbilityInputID::None),/**ConfirmTargetInputID*/         
    static_cast(EGASAbilityInputID::None)/**CancelTargetInputID*/ ) );
} 
/*关于Confirm和Cancel: 
 技能基本走的是这样的套路： 
 技能激活 --> 选择目标 --> 确认/取消 目标 --> 释放技能效果/中断技能
**/

• 技能ID与所释放技能的绑定

  void Character::PossessedBy(AController* NewController)
   { 
      Super::PossessedBy(NewController);
     if(GetLocalRole() != ROLE_Authority || !IsValid(AbilitySystemComponent)) {
       return /**处理多人游戏*/;
   } 
  //给与技能 
  AbilitySystemComponent->GiveAbility( 
    FGameplayAbilitySpec( 
      UGameplayAbility_CharacterJump::StaticClass(),//使用GAS自带的跳跃技能实现
      1,
      static_cast(EGASAbilityInputID::Jump),
      this)
 ); 
  //SprintAbility可以在蓝图实现 
  //UPROPERTY(BlueprintReadOnly, EditAnywhere) 
  //TSubclassOf SprintAbility; 
  if(SprintAbility) { 
    AbilitySystemComponent->GiveAbility( 
      FGameplayAbilitySpec( 
        SprintAbility,
        1, 
        static_cast(EGASAbilityInputID::Sprint),
        this )
   );
 } 
/*关于蓝图实现技能:
   创建GameplayAbility的子蓝图，实现EventActivateAbility
**/
} 

AbilitySet & GameplayEffect