75 lines
2.8 KiB
Markdown
75 lines
2.8 KiB
Markdown
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## 概述
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在GameplayAbility框架中，UAttributeSet负责管理各种属性。
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## 定义宏
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在头文件中添加：
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```
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// 使用AttributeSet.h的宏
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#define ATTRIBUTE_ACCESSORS(ClassName, PropertyName) \
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GAMEPLAYATTRIBUTE_PROPERTY_GETTER(ClassName, PropertyName) \
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GAMEPLAYATTRIBUTE_VALUE_GETTER(PropertyName) \
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GAMEPLAYATTRIBUTE_VALUE_SETTER(PropertyName) \
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GAMEPLAYATTRIBUTE_VALUE_INITTER(PropertyName)
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```
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参考注释可以得知，使用这些宏可以让你少写各个属性的Get、Set、Init函数。如果不使用这个宏你也可以自己实现对应的函数。
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这里用到了Ue4的反射。
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## 添加属性
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再以下格式添加属性：
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```
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UPROPERTY(BlueprintReadOnly, Category = "Health")
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FGameplayAttributeData Health;
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ATTRIBUTE_ACCESSORS(URPGAttributeSet, Health)
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```
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## 重写接口
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ActionRPG案例中重写了PreAttributeChange与PostGameplayEffectExecute接口。
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前者会在属性被修改时调用，在案例中是为了在血量或魔法上限发生变动时，按比例调整当前血量或者魔法值。后者与GameplayEffect有关，等到编写完GameplayEffect时，再来编写。
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```
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void URPGAttributeSet::PreAttributeChange(const FGameplayAttribute & Attribute, float & NewValue)
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{
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Super::PreAttributeChange(Attribute, NewValue);
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if (Attribute == GetMaxHealthAttribute())
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{
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AdjustAttributeForMaxChange(Health, MaxHealth, NewValue, GetHealthAttribute());
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}
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else if (Attribute == GetMaxManaAttribute())
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{
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AdjustAttributeForMaxChange(Mana, MaxMana, NewValue, GetManaAttribute());
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}
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}
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void URPGAttributeSet::PostGameplayEffectExecute(const FGameplayEffectModCallbackData & Data)
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{
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Super::PostGameplayEffectExecute(Data);
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}
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void URPGAttributeSet::AdjustAttributeForMaxChange(FGameplayAttributeData& AffectedAttribute, const FGameplayAttributeData& MaxAttribute, float NewMaxValue, const FGameplayAttribute& AffectedAttributeProperty)
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{
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UAbilitySystemComponent* AbilityComp = GetOwningAbilitySystemComponent();
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const float CurrentMaxValue = MaxAttribute.GetCurrentValue();
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if (!FMath::IsNearlyEqual(CurrentMaxValue, NewMaxValue) && AbilityComp)
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{
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// Change current value to maintain the current Val / Max percent
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const float CurrentValue = AffectedAttribute.GetCurrentValue();
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float NewDelta = (CurrentMaxValue > 0.f) ? (CurrentValue * NewMaxValue / CurrentMaxValue) - CurrentValue : NewMaxValue;
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AbilityComp->ApplyModToAttributeUnsafe(AffectedAttributeProperty, EGameplayModOp::Additive, NewDelta);
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}
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}
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```
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## 个人的使用方案
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定义URPGAttributeSet作为基础属性集，里面定义通用属性。之后又定义URPGCharacterAttributeSet作为角色专用的属性集。
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之后在角色类中的构造函数中挂载URPGAttributeSet对象。
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```
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UPROPERTY()
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URPGAttributeSet* AttributeSet;
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```
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```
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AttributeSet = CreateDefaultSubobject<URPGAttributeSet>(TEXT("AttributeSet"));
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```
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