UE4 基于GAS的插件ArcInventory拆解-4_库存组件子类：UArcInventoryComponent_Bag/Equipable/Active

小咪咪 2022-09-11 00:23 185阅读 0赞

# 一、UArcInventoryComponent\_Bag #

最朴素的背包

## 1.1、属性 ##

UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = Inventory)
    	int32 BagSlotCount;
    	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Inventory", meta = (AllowPrivateAccess = "true"))
    	FGameplayAttribute InventorySizeAttribute;

### 1.1.1、BagSlotCount ###

插槽数量

### 1.1.2、InventorySizeAttribute ###

插槽数量(由Attribute控制)，当`InventorySizeAttribute`存在时使用`InventorySizeAttribute`

# 二、接口 #

virtual void UpdateBagInventorySlots();
    UFUNCTION(BlueprintCallable, Category = "Inventory | Item Queries", meta = (ScriptName = "ItemQuery_GetAllBagSlots"))

## 1.2、UpdateBagInventorySlots ##

**作用：**  
根据插槽数量动态更新插槽

void UArcInventoryComponent_Bag::UpdateBagInventorySlots()
    {
        
    	//1、获取到当前插槽数量
    	FGameplayTag BagTag = GetDefault<UArcInventoryDeveloperSettings>()->BagItemSlotTag;
    	TArray<FArcInventoryItemSlotReference> Slots;
    	Query_GetAllBagSlots(Slots);
    	int32 SlotCount = Slots.Num();
    
    	//2、计算应有数量与当前数量的差值
    	int32 BagSlotsToCreate = BagSlotCount - SlotCount;
    	
    	//3、多退少补
    	if (BagSlotsToCreate > 0){
        
    		for (int32 i = 0; i < BagSlotsToCreate; i++){
        
    			CreateInventorySlot(BagTag.GetSingleTagContainer(), nullptr);}}
    	else if(BagSlotsToCreate < 0){
        
    		//remove the bottom slots
    		for (int i = 0; i < FMath::Abs(BagSlotsToCreate); i++){
        
    			int32 SlotToRemove = SlotCount - 1 - i;
    			RemoveInventorySlot(Slots[SlotToRemove]);}}
    }

**实现：**  
计算所需插槽数-当前插槽数的差值，多了的话从最后一个插槽开始删除，少了的话添加新的

## 1.3、总结 ##

**只有一个功能：**  
根据插槽数量添加/删除背包插槽  
由于大部分功能父类已经实现，`UArcInventoryComponent_Bag`仅仅需要确定背包插槽数量并调用父类的创建和删除就行

# 二、UArcInventoryComponent\_Equippable #

可以放置装备的背包组件

## 2.1、属性 ##

UPROPERTY(BlueprintReadOnly, EditDefaultsOnly, Category = "Abilities", Replicated, meta = (AllowPrivateAccess = "true"))
    TArray< FArcInventoryItemInfoEntry> EquippedItemAbilityInfos;

### 2.1.1、EquippedItemAbilityInfos ###

**作用：**  
一个储存了装备信息的数组

USTRUCT(BlueprintType)
    struct FArcInventoryItemInfoEntry
    {
        
    	UPROPERTY(BlueprintReadOnly, Category = "Abilities")
    		FArcInventoryItemSlotReference ItemSlotRef;
    	UPROPERTY(BlueprintReadOnly, Category = "Abilities")
    		FArcEquippedItemInfo EquippedItemInfo;
    };

**实现：**  
记录`ItemRef`以及其增加的`GA`、`GE`、`AttributeSet`留待装备被移出自己的插槽时回退。

### 2.1.2、FArcEquippedItemInfo ###

储存`GA`、`GE`、`AttributeSet`的集合

> 之后会以`AbilityInfo`描述`GA`、`GE`、`AttributeSet`的集合

//储存GA、GE、AttributeSet
    USTRUCT(BlueprintType)
    struct ARCINVENTORY_API FArcEquippedItemInfo
    {
        
    public:
    	FArcEquippedItemInfo(){
        }
    	UPROPERTY()
    	TArray<FGameplayAbilitySpecHandle> AddedAbilities;
    	UPROPERTY()
    	TArray<UAttributeSet*> InstancedAttributeSets;
    	UPROPERTY()
    	TArray< FActiveGameplayEffectHandle> AddedGameplayEffects;
    };

## 2.2、接口 ##

UFUNCTION()
    virtual void OnItemEquipped(class UArcInventoryComponent* Inventory, const FArcInventoryItemSlotReference& ItemSlotRef, UArcItemStack* ItemStack, UArcItemStack* PreviousItemStack);

### 2.2.1、当物品更换时：OnItemEquipped ###

**作用：**  
装备放入/取出与交换的入口。所有`ItemSlot`都绑定了该函数  
或许叫OnEquipItemChanged更合适

void UArcInventoryComponent_Equippable::OnItemEquipped(class UArcInventoryComponent* Inventory, const FArcInventoryItemSlotReference& ItemSlotRef, UArcItemStack* ItemStack, UArcItemStack* PreviousItemStack)
    {
        
    	if (IsValid(PreviousItemStack) && IsEquippedItemSlot(ItemSlotRef)){
        
    		MakeItemUnequipped_Internal(ItemSlotRef, PreviousItemStack);}
    	if (IsValid(ItemStack) && IsEquippedItemSlot(ItemSlotRef)){
        
    		MakeItemEquipped_Internal(ItemSlotRef, ItemStack);}
    }

**实现：**  
只要物品槽有变动就会调用，如果是装备栏则根据取出/放入操作执行对应的内部函数

### 2.2.2、放入装备：MakeItemEquipped\_Internal ###

**作用：**  
给放入装备插槽的物品

bool UArcInventoryComponent_Equippable::MakeItemEquipped_Internal(const FArcInventoryItemSlotReference& ItemSlot, UArcItemStack* ItemStack)
    {
        
    	//1、获取Definition
    	TSubclassOf<UArcItemDefinition_Equipment> ItemDefinition(ItemStack->GetItemDefinition());
    	if (!IsValid(ItemDefinition)){
        
    		return false;}
    		
    	//2、获取Entry
    	//2.1、已经有了则获取
    	FArcInventoryItemInfoEntry* Entry = EquippedItemAbilityInfos.FindByPredicate([ItemSlot](FArcInventoryItemInfoEntry& x) {
        
    		return x.ItemSlotRef.SlotId == ItemSlot.SlotId;});
    	//2.2、没有则创建
    	if (Entry == nullptr){
        
    		Entry = &EquippedItemAbilityInfos.Add_GetRef(FArcInventoryItemInfoEntry(ItemSlot));}
    	
    	//3、应用Definition中的Ability和AttributeSet
    	bool bSuccess = ApplyAbilityInfo_Internal(ItemDefinition.GetDefaultObject()->EquippedItemAbilityInfo, (*Entry).EquippedItemInfo, ItemStack);
    	if (bSuccess){
        
    		//应用Attribute修改器
    		ApplyPerks(ItemStack, ItemSlot);
    		//广播修改
    		OnEquippedItem.Broadcast(this, ItemSlot, ItemStack);}
    	return 	bSuccess;
    }

**实现：**  
获取物品的AbilityInfo并应用，将Entry放入

### 2.2.2、取出装备：MakeItemUnequipped\_Internal ###

bool UArcInventoryComponent_Equippable::MakeItemUnequipped_Internal(const FArcInventoryItemSlotReference& ItemSlot, UArcItemStack* ItemStack)
    {
        
    	//1、取出ItemDefinition和Entry
    	TSubclassOf<UArcItemDefinition_Equipment> ItemDefinition(ItemStack->GetItemDefinition());
    	FArcInventoryItemInfoEntry* Entry = EquippedItemAbilityInfos.FindByPredicate([ItemSlot](FArcInventoryItemInfoEntry& x) {
        
    		return x.ItemSlotRef.SlotId == ItemSlot.SlotId;
    	});
    	
    	//2、移除Perk以及清空AbilityInfo
    	RemovePerks(ItemStack, ItemSlot);
    	bool bSuccess = ClearAbilityInfo_Internal(ItemDefinition.GetDefaultObject()->EquippedItemAbilityInfo, (*Entry).EquippedItemInfo);
    
    	//3、广播
    	if (bSuccess){
        
    		OnUnEquippedItem.Broadcast(this, ItemSlot, ItemStack);}
    	return 	bSuccess;
    }

## 2.3、总结 ##

装备背包的实现非常简单。根据Tag查找可以装备的`ItemSlot`，当`ItemSlot`变换时将对应`ItemStack`的`AbilityInfo`(`GA`、`GE`、`AttributeSet`的集合)进行应用或移除。  
可以看到，无论变换的是什么背包，`ItemSlot`的类型始终是不变的，

# 三、UArcInventoryComponent\_Active #

激活物背包，只有一个物品能被激活  
用于放置武器等互斥物品以及对应的切换操作  
目前较为复杂的部分，也是深入理解ArcInventoryComponent的重要部分

## 3.1、属性 ##

UPROPERTY(VisibleInstanceOnly, BlueprintReadOnly, ReplicatedUsing = OnRep_ActiveItemSlot, Category = "Inventory")
    		int32 ActiveItemSlot;
    UPROPERTY(VisibleInstanceOnly, BlueprintReadWrite, ReplicatedUsing = OnRep_PendingItemSlot, Category = "Inventory")
    		int32 PendingItemSlot;
    TArray<FArcInventoryItemSlotReference> CachedActiveItemSlots;

### 3.1.1、ActiveItemSlot ###

正在激活中的SlotID

### 3.1.2、PendingItemSlot ###

准备激活的SlotID

### 3.1.3、CachedActiveItemSlots ###

所有的可激活物品引用

## 3.2、接口 ##

void UArcInventoryComponent_Active::UpdateActiveItemSlots(UArcInventoryComponent* InventoryComp);

### 3.2.1、UpdateActiveItemSlots ###

**作用：**  
将满足`ActiveSlotTag`的`ItemSlot`放入`CachedActiveItemSlots`中

void UArcInventoryComponent_Active::UpdateActiveItemSlots(UArcInventoryComponent* InventoryComp)
    {
        
    	FGameplayTag ActiveSlotTag = GetDefault<UArcInventoryDeveloperSettings>()->ActiveItemSlotTag;
    	CachedActiveItemSlots.Empty(CachedActiveItemSlots.Num());
    	Query_GetAllSlots(FArcInventoryQuery::QuerySlotMatchingTag(ActiveSlotTag), CachedActiveItemSlots);
    }

**实现：**  
调用父类的`Query_GetAllSlots`将查到的`ItemSlot`塞进`CachedActiveItemSlots`中

### 3.2.2、BeginPlay ###

**作用：**  
激活默认ActiveItem

void UArcInventoryComponent_Active::BeginPlay()
    {
        
    	//激活默认物品
    	GetWorld()->GetTimerManager().SetTimerForNextTick([this]()
    	{
        
    		//检查第一个插槽是否是被Active，是的话激活(客户端方法)
    		if (PendingItemSlot != INDEX_NONE){
        
    			this->SwitchToPendingItemSlot();}
    		//有时在客户端ActiveItemSlot已经有值但PendingItemSlot还没有被同步过来，则直接执行MakeItemActive
    		else if (ActiveItemSlot != INDEX_NONE && GetOwnerRole() != ROLE_Authority){
        
    			this->MakeItemActive(ActiveItemSlot);}});
    	Super::BeginPlay();
    }

### 3.2.3、SwitchToPendingItemSlot ###

**作用：**  
切换激活物品为`PendingItemSlot`

void UArcInventoryComponent_Active::SwitchToPendingItemSlot()
    {
        
    	//1、尝试让ASC自行处理
    	bool bActivatedAbility = false;
    	if (UAbilitySystemComponent* ASC = UAbilitySystemGlobals::Get().GetAbilitySystemComponentFromActor(GetOwner())){
        
    		FGameplayTag SwitchWeaponsAbilityTag = FGameplayTag::RequestGameplayTag(TEXT("Ability.ItemSwitch.Pending"), false);
    		if (SwitchWeaponsAbilityTag.IsValid()){
        
    			bActivatedAbility = ASC->TryActivateAbilitiesByTag(FGameplayTagContainer(SwitchWeaponsAbilityTag));}}
    			
    	//2、无法自行处理：先注销源ItemSlot，再激活PendingItemSlot
    	if (!bActivatedAbility)//Otherwise just quickly switch the item{
        
    		MakeItemInactive();
    		MakeItemActive(PendingItemSlot);}
    		
    	//3、重置PendingItemSlot 
    	PendingItemSlot = INDEX_NONE;
    }

**方法：**  
尝试让ASC自行处理，如果无法处理则先注销再激活

### 3.2.4、激活物品 ###

**作用：**  
根据插槽ID激活物品对应的`AbilityInfo`  
MakeItemActive

void UArcInventoryComponent_Active::MakeItemActive(int32 NewActiveItemSlot)
    {
        
    	//1、根据SlotID获取SlotRef
    	FArcInventoryItemSlotReference ItemSlotRef = CachedActiveItemSlots[NewActiveItemSlot];
    	
    	//2、执行内部激活函数
    	if (!MakeItemActive_Internal(ItemSlotRef)){
        
    		if (IsValid(GetItemInSlot(ItemSlotRef))){
        
    			//激活失败但是Slot确实存在，则重置NewActiveItemSlot 
    			NewActiveItemSlot = INDEX_NONE;}}
    
    	//3、设置ActiveItemSlot 
    	ActiveItemSlot = NewActiveItemSlot;
    }

MakeItemActive\_Internal(const FArcInventoryItemSlotReference& ItemSlot)

bool UArcInventoryComponent_Active::MakeItemActive_Internal(const FArcInventoryItemSlotReference& ItemSlot)
    {
        
    	UArcItemStack* ItemStack = GetItemInSlot(ItemSlot);
    	return MakeItemActive_Internal(ItemSlot, ItemStack);
    }

MakeItemActive\_Internal(const FArcInventoryItemSlotReference& ItemSlot, UArcItemStack\* ItemStack)

bool UArcInventoryComponent_Active::MakeItemActive_Internal(const FArcInventoryItemSlotReference& ItemSlot, UArcItemStack* ItemStack)
    {
        
    	//1、获取Definition
    	TSubclassOf<UArcItemDefinition_Active> ItemDefinition(ItemStack->GetItemDefinition());
    	
    	//2、获取Entry，有的话直接拿，没有的话创建一个
    	FArcInventoryItemInfoEntry* Entry = ActiveItemAbilityInfos.FindByPredicate([ItemSlot](const FArcInventoryItemInfoEntry& x) {
        
    		return x.ItemSlotRef.SlotId == ItemSlot.SlotId;});
    	if (Entry == nullptr){
        
    		Entry = &ActiveItemAbilityInfos.Add_GetRef(FArcInventoryItemInfoEntry(ItemSlot));}
    
    	//3、应用能力与Perk，调用Equipment的ApplyAbilityInfo_Internal
    	bool bSuccess = ApplyAbilityInfo_Internal(ItemDefinition.GetDefaultObject()->ActiveItemAbilityInfo, (*Entry).EquippedItemInfo, ItemStack);
    	if (bSuccess){
        
    		ApplyPerks(ItemStack, ItemSlot);}
    	
    	//4、广播激活
    	OnItemActive.Broadcast(this, ItemStack);
    	return bSuccess;
    }

**实现：**  
根据ID查找到Stack内部的ItemInfo并应用

### 3.2.5、注销物品 ###

**作用：**  
将目前正在激活的物品注销

MakeItemInactive

void UArcInventoryComponent_Active::MakeItemInactive()
    {
        
    	//1、执行内部注销函数
    	MakeItemInactive_Internal(GetActiveItemSlot());
    	
    	//2、没有新的武器切换，则重置ActiveItemSlot 
    	if (/*GetOwnerRole() == ROLE_Authority &&*/ !bSwitchingWeapons){
        
    		ActiveItemSlot = INDEX_NONE;}
    }

MakeItemInactive\_Internal(1参数)

bool UArcInventoryComponent_Active::MakeItemInactive_Internal(const FArcInventoryItemSlotReference& ItemSlot)
    {
        
    	UArcItemStack* ItemStack = GetItemInSlot(ItemSlot);
    	return MakeItemInactive_Internal(ItemSlot, ItemStack);
    }

MakeItemInactive\_Internal(2参数)

bool UArcInventoryComponent_Active::MakeItemInactive_Internal(const FArcInventoryItemSlotReference& ItemSlot, UArcItemStack* ItemStack)
    {
        
    	//1、处理当服务器已经移除了当前ItemSlot但客户端还没有移除时，仅仅调用Inactive的广播
    	if (!IsValid(ItemStack)){
        
    		if (IsValid(ItemSlot)){
        
    			OnItemInactive.Broadcast(this, ItemStack);}
    		return false;}
    	
    	//2、获取ItemDefinition与缓存在ActiveItemAbilityInfos的Entry
    	TSubclassOf<UArcItemDefinition_Active> ItemDefinition(ItemStack->GetItemDefinition());
    	FArcInventoryItemInfoEntry* Entry = ActiveItemAbilityInfos.FindByPredicate([ItemSlot](const FArcInventoryItemInfoEntry& x) {
        
    		return x.ItemSlotRef.SlotId == ItemSlot.SlotId;});
    	
    	//3、移除Perk和所有装备信息
    	RemovePerks(ItemStack, ItemSlot);
    	bool bSuccess = ClearAbilityInfo_Internal(ItemDefinition.GetDefaultObject()->ActiveItemAbilityInfo, (*Entry).EquippedItemInfo);
    		
    	//4、广播已经被移除
    	OnItemInactive.Broadcast(this, ItemStack);
    	return bSuccess;
    }

**实现：**  
直接找到当前激活Item并移除`AbilityInfo`

### 3.2.6、回调重写OnItemEquipped ###

**作用：**  
当物品被装备/卸下时回调

void UArcInventoryComponent_Active::OnItemEquipped(class UArcInventoryComponent* Inventory, const FArcInventoryItemSlotReference& ItemSlotRef, UArcItemStack* ItemStack, UArcItemStack* PreviousItemStack)
    {
        
    	Super::OnItemEquipped(Inventory, ItemSlotRef, ItemStack, PreviousItemStack);
    	
    	//1、如果是放入，当是第一个ActiveItem时，激活该物品
    	if (ActiveItemSlot == INDEX_NONE && IsActiveItemSlot(ItemSlotRef) && IsValid(ItemStack)){
        
    		int32 ItemSlotIndex = GetActiveItemIndexBySlotRef(ItemSlotRef);
    		PendingItemSlot = ItemSlotIndex;
    		if (HasBegunPlay()){
        
    			SwitchToPendingItemSlot();}}
    
    	//2、当移除激活的物品，激活下一个可以激活的物品
    	if (!IsValid(ItemStack)){
        
    		int32 ItemSlotIndex = GetActiveItemIndexBySlotRef(ItemSlotRef);
    		if (ItemSlotIndex == ActiveItemSlot){
        
    			PendingItemSlot = GetNextValidActiveItemSlot();
    			MakeItemInactive_Internal(ItemSlotRef, PreviousItemStack);
    			SwitchToPendingItemSlot();}}}

**实现：**  
当放入的是一个可激活物时，自动装备  
当移除的是当前激活物时，自动装备下一件物品

### 3.2.7、交换 ###

**作用：**  
交换激活的物品

void UArcInventoryComponent_Active::SwapActiveItems(int32 NewItemSlot){
        
    	bSwitchingWeapons = true;
    	MakeItemInactive();
    	MakeItemActive(NewItemSlot);
    	bSwitchingWeapons = false;
    }

**实现：**  
移除原有激活物，激活新激活物

### 3.2.8、获取 ###

<table> 
 <thead> 
  <tr> 
   <th>函数</th> 
   <th>作用</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>GetActiveItemStack</td> 
   <td>获取当前激活的<code>ItemStack</code></td> 
  </tr> 
  <tr> 
   <td>GetNextActiveItemSlot</td> 
   <td>获取下一个<code>ActiveItemSlot</code></td> 
  </tr> 
  <tr> 
   <td>GetPreviousActiveItemSlot</td> 
   <td>获取上一个<code>ActiveItemSlot</code></td> 
  </tr> 
  <tr> 
   <td>GetNextValidActiveItemSlot</td> 
   <td>获取下一个存在<code>ItemStack</code>的<code>ActiveItemSlot</code></td> 
  </tr> 
  <tr> 
   <td>GetPreviousValidActiveItemSlot</td> 
   <td>获取上一个存在<code>ItemStack</code>的<code>ActiveItemSlot</code></td> 
  </tr> 
 </tbody> 
</table>

## 3.3、总结 ##

提供了基础的物品激活功能  
对于Equip进行限制的产物，仅允许一种激活物品存在  
激活物最麻烦的是同步与联机问题

# 四、总结 #

`UArcInventoryComponent_Bag`：根据数量动态设置普通`ItemSlot`  
`UArcInventoryComponent_Equipable`：接入GAS，能将装备放入`ItemSlot`中并应用`AbilityInfo`  
`UArcInventoryComponent_Active`：仅允许一个`AbilityInfo`被激活  
基本完成了ArcInventory的拼图