Lyra学习笔记2 GFA_AddComponents与ULyraPlayerSpawningManagerComponent

前言

1.以control模式为例
2.比较散，想单独拿出一篇梳理下Experience的流程

GameFeatureAction_AddComponents

这部分建议看
《InsideUE5》GameFeatures架构（五）AddComponents
这里写的内容相当于是我跟着走了一遍

Lyra中角色基本类ALyraCharacter类似于一个框架，负责转发事件给其组件，组件实现相关功能，所以ALyraCharacter甚至只有几百行（在这个不算小的项目里这真的算短了（我觉得））。

在研究生成角色流程之前，我想先研究一下GameFeatureAction中的AddComponents,帮助之后的理解。

在加载Experience的过程中，执行到ULyraExperienceManagerComponent::OnExperienceLoadComplete时会激活GameFeature,以AddComponents为例，一直到OnGameFeatureActivating的调用栈如图：

而在OnGameFeatureActivating中都会调用到AddToWorld
前面经过一些World，客户端服务端之类的判断后，执行逻辑在如下的一行：

void UGameFeatureAction_AddComponents::AddToWorld(const FWorldContext& WorldContext, FContextHandles& Handles) {... 
Handles.ComponentRequestHandles.Add(GFCM->AddComponentRequest(Entry.ActorClass, ComponentClass, static_cast<EGameFrameworkAddComponentFlags>(Entry.AdditionFlags))); 
... 
}

GFCM::AddComponentRequest

TSharedPtr<FComponentRequestHandle> UGameFrameworkComponentManager::AddComponentRequest(const TSoftClassPtr<AActor>& ReceiverClass, TSubclassOf<UActorComponent> ComponentClass, const EGameFrameworkAddComponentFlags AdditionFlags)
{// You must have a receiver and component class. The receiver cannot be AActor, that is too broad and would be bad for performance.if (!ensure(!ReceiverClass.IsNull()) || !ensure(ComponentClass) || !ensure(ReceiverClass.ToString() != TEXT("/Script/Engine.Actor"))){return nullptr;}//一些检查FComponentRequestReceiverClassPath ReceiverClassPath(ReceiverClass);UClass* ComponentClassPtr = ComponentClass.Get();FComponentRequest NewRequest;NewRequest.ReceiverClassPath = ReceiverClassPath;NewRequest.ComponentClass = ComponentClassPtr;// Add a request if there is not an already existing one. Note that it will only uses the receiver and component class to check for uniqueness, not the addition flags.int32& RequestCount = RequestTrackingMap.FindOrAdd(NewRequest);RequestCount++;if (RequestCount == 1)//第一次匹配{EGameFrameworkAddComponentResult Result = EGameFrameworkAddComponentResult::Failed;auto& RequestInfoSet = ReceiverClassToComponentClassMap.FindOrAdd(ReceiverClassPath);RequestInfoSet.Add({ ComponentClassPtr, AdditionFlags } );if (UClass* ReceiverClassPtr = ReceiverClass.Get()){UGameInstance* LocalGameInstance = GetGameInstance();if (ensure(LocalGameInstance)){UWorld* LocalWorld = LocalGameInstance->GetWorld();if (ensure(LocalWorld)){for (TActorIterator<AActor> ActorIt(LocalWorld, ReceiverClassPtr); ActorIt; ++ActorIt)//遍历场景中的Actor{if (ActorIt->IsActorInitialized())//调用过BeginPlay{
#if WITH_EDITORif (!ReceiverClassPtr->HasAllClassFlags(CLASS_Abstract)){ensureMsgf(AllReceivers.Contains(*ActorIt), TEXT("You may not add a component request for an actor class that does not call AddReceiver/RemoveReceiver in code! Class:%s"), *GetPathNameSafe(ReceiverClassPtr));}
#endifResult = CreateComponentOnInstance(*ActorIt, ComponentClass, AdditionFlags);//创建组件}}}}}else{// Actor class is not in memory, there will be no actor instances}return MakeShared<FComponentRequestHandle>(this, ReceiverClass, ComponentClass);}return nullptr;
}

EGameFrameworkAddComponentResult UGameFrameworkComponentManager::CreateComponentOnInstance(AActor* ActorInstance, TSubclassOf<UActorComponent> ComponentClass, const EGameFrameworkAddComponentFlags AdditionFlags)
{...UActorComponent* NewComp = NewObject<UActorComponent>(ActorInstance, ComponentClass, NewComponentName);...
}

一些细节原文写的很好《InsideUE5》GameFeatures架构（五）AddComponents

ULyraPlayerSpawningManagerComponent

总结一下目前为止的流程：

读取WordSetting中的Experience->
GameState中的ULyraExperienceManagerComponent加载Experience->
激活Experience中配置的GameFeature->
执行Actions

Control关卡中的B_LyraShooterGame_ControlPoints（Experience）的Actions中，
有添加组件的Action，其中配置了在LyraGameState中添加ULyraPlayerSpawningManagerComponent，这个组件负责了管理生成位置。

缓存所有PlayerStart位置

void ULyraPlayerSpawningManagerComponent::InitializeComponent()
{Super::InitializeComponent();UE_LOG(LogTemp,Warning,TEXT("LAPI: ULyraPlayerSpawningManagerComponent::InitializeComponent"));FWorldDelegates::LevelAddedToWorld.AddUObject(this, &ThisClass::OnLevelAdded);UWorld* World = GetWorld();World->AddOnActorSpawnedHandler(FOnActorSpawned::FDelegate::CreateUObject(this, &ThisClass::HandleOnActorSpawned));for (TActorIterator<ALyraPlayerStart> It(World); It; ++It){if (ALyraPlayerStart* PlayerStart = *It){CachedPlayerStarts.Add(PlayerStart);}}
}

直接看后半部分可知缓存了场景中所有的PlayerStart。
再来看OnLevelAdded这个函数：

void ULyraPlayerSpawningManagerComponent::OnLevelAdded(ULevel* InLevel, UWorld* InWorld)
{if (InWorld == GetWorld()){for (AActor* Actor : InLevel->Actors){if (ALyraPlayerStart* PlayerStart = Cast<ALyraPlayerStart>(Actor)){ensure(!CachedPlayerStarts.Contains(PlayerStart));CachedPlayerStarts.Add(PlayerStart);}}}
}

这里是新的Level被AddToWorld的时候调用的，以实现更新PlayerStart，从L_DefaultEditorOverview到L_Convolution_Blockout并不会触发，因为是加载组件之后才绑定的。
同理HandleOnActorSpawned是负责处理动态生成的PlayerStart的。

选择位置

加载完地图资源后，GameMode会将ChoosePlayerStart转到SpawningManagerComponent的ChoosePlayerStart函数：

Choose函数比较长

AActor* ULyraPlayerSpawningManagerComponent::ChoosePlayerStart(AController* Player)
{if (Player){
#if WITH_EDITORif (APlayerStart* PlayerStart = FindPlayFromHereStart(Player)){return PlayerStart;}
#endif//这部分处理编辑器中PlayFromHere的PlayerStartPIE的特殊情况TArray<ALyraPlayerStart*> StarterPoints;for (auto StartIt = CachedPlayerStarts.CreateIterator(); StartIt; ++StartIt){if (ALyraPlayerStart* Start = (*StartIt).Get()){StarterPoints.Add(Start);}else{StartIt.RemoveCurrent();}}//处理完后StarterPoints存的是安全的强引用if (APlayerState* PlayerState = Player->GetPlayerState<APlayerState>()){// start dedicated spectators at any random starting location, but they do not claim itif (PlayerState->IsOnlyASpectator()){if (!StarterPoints.IsEmpty()){return StarterPoints[FMath::RandRange(0, StarterPoints.Num() - 1)];}return nullptr;}}//若是Spectators在数组内随机一个位置返回AActor* PlayerStart = OnChoosePlayerStart(Player, StarterPoints);//返回nullptrif (!PlayerStart)//若为nullptr，暂时必然为nullptr{PlayerStart = GetFirstRandomUnoccupiedPlayerStart(Player, StarterPoints);//若有未占用，则在其中随机一个，若没有就在已经占用的随机一个}if (ALyraPlayerStart* LyraStart = Cast<ALyraPlayerStart>(PlayerStart)){LyraStart->TryClaim(Player);//尝试占用}return PlayerStart;}return nullptr;
}

待续…