BTNode.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "UObject/ObjectMacros.h"
#include "UObject/Object.h"
#include "BehaviorTree/BehaviorTreeTypes.h"
#include "BehaviorTree/BehaviorTreeComponent.h"
#include "BehaviorTree/BlackboardAssetProvider.h"
#include "GameplayTaskOwnerInterface.h"
#include "Tasks/AITask.h"
#include <type_traits>
#include "BTNode.generated.h"
 
class AActor;
class ISlateStyle;
class UBehaviorTree;
class UBlackboardData;
class UBTCompositeNode;
class UGameplayTasksComponent;
 
AIMODULE_API DECLARE_LOG_CATEGORY_EXTERN(LogBehaviorTree, Display, All);
 
class AAIController;
class UWorld;
class UBehaviorTree;
class UBehaviorTreeComponent;
class UBTCompositeNode;
class UBlackboardData;
struct FBehaviorTreeSearchData;
 
struct FBTInstancedNodeMemory
{
    int32 NodeIdx;
};
 
struct FBehaviorTreeNodeDebugContext
{
    UBehaviorTreeComponent& OwnerComponent;
    FString RuntimeDescription;
};
 
UCLASS(Abstract, config=Game, MinimalAPI)
class UBTNode : public UObject, public IGameplayTaskOwnerInterface
{
    GENERATED_UCLASS_BODY()
 
    AIMODULE_API virtual UWorld* GetWorld() const override;
 
    AIMODULE_API void InitializeNode(UBTCompositeNode* InParentNode, uint16 InExecutionIndex, uint16 InMemoryOffset, uint8 InTreeDepth);
 
    AIMODULE_API virtual void InitializeFromAsset(UBehaviorTree& Asset);
    
    AIMODULE_API virtual void InitializeMemory(UBehaviorTreeComponent& OwnerComp, uint8* NodeMemory, EBTMemoryInit::Type InitType) const;
 
    AIMODULE_API virtual void CleanupMemory(UBehaviorTreeComponent& OwnerComp, uint8* NodeMemory, EBTMemoryClear::Type CleanupType) const;
 
    AIMODULE_API virtual void DescribeRuntimeValues(const UBehaviorTreeComponent& OwnerComp, uint8* NodeMemory, EBTDescriptionVerbosity::Type Verbosity, TArray<FString>& Values) const;
 
    AIMODULE_API virtual uint16 GetInstanceMemorySize() const;
 
    AIMODULE_API virtual void OnInstanceCreated(UBehaviorTreeComponent& OwnerComp);
 
    AIMODULE_API virtual void OnInstanceDestroyed(UBehaviorTreeComponent& OwnerComp);
 
    AIMODULE_API void InitializeInSubtree(UBehaviorTreeComponent& OwnerComp, uint8* NodeMemory, int32& NextInstancedIndex, EBTMemoryInit::Type InitType) const;
 
    AIMODULE_API void CleanupInSubtree(UBehaviorTreeComponent& OwnerComp, uint8* NodeMemory, EBTMemoryClear::Type CleanupType) const;
 
    AIMODULE_API virtual uint16 GetSpecialMemorySize() const;
 
#if USE_BEHAVIORTREE_DEBUGGER
    AIMODULE_API void InitializeExecutionOrder(UBTNode* NextNode);
 
    UBTNode* GetNextNode() const;
#endif
 
    template<typename T>
    T* InitializeNodeMemory(uint8* NodeMemory, EBTMemoryInit::Type InitType) const;
 
    template <typename T>
    void CleanupNodeMemory(uint8* NodeMemory, EBTMemoryClear::Type CleanupType) const;
 
    template<typename T>
    T* GetNodeMemory(FBehaviorTreeSearchData& SearchData) const;
 
    template<typename T>
    const T* GetNodeMemory(const FBehaviorTreeSearchData& SearchData) const;
 
    template<typename T>
    T* GetNodeMemory(FBehaviorTreeInstance& BTInstance) const;
 
    template<typename T>
    const T* GetNodeMemory(const FBehaviorTreeInstance& BTInstance) const;
 
    template<typename T>
    T* CastInstanceNodeMemory(uint8* NodeMemory) const;
 
    template<typename T>
    T* GetSpecialNodeMemory(uint8* NodeMemory) const;
 
    UBTCompositeNode* GetParentNode() const;
 
    AIMODULE_API FString GetNodeName() const;
 
    uint16 GetExecutionIndex() const;
 
    uint16 GetMemoryOffset() const;
 
    uint8 GetTreeDepth() const;
 
    void MarkInjectedNode();
 
    bool IsInjected() const;
 
    void ForceInstancing(bool bEnable);
 
    bool HasInstance() const;
 
    bool IsInstanced() const;
 
    UBehaviorTree* GetTreeAsset() const;
 
    AIMODULE_API UBlackboardData* GetBlackboardAsset() const;
 
    AIMODULE_API UBTNode* GetNodeInstance(const UBehaviorTreeComponent& OwnerComp, uint8* NodeMemory) const;
    AIMODULE_API UBTNode* GetNodeInstance(FBehaviorTreeSearchData& SearchData) const;
 
    AIMODULE_API FString GetRuntimeDescription(const UBehaviorTreeComponent& OwnerComp, uint8* NodeMemory, EBTDescriptionVerbosity::Type Verbosity) const;
 
    AIMODULE_API virtual FString GetStaticDescription() const;
 
#if WITH_EDITOR
    AIMODULE_API virtual const ISlateStyle& GetNodeIconStyleSet() const;
 
    AIMODULE_API virtual FName GetNodeIconName() const;
 
    AIMODULE_API virtual bool UsesBlueprint() const;
 
    AIMODULE_API virtual FString GetErrorMessage() const;
 
    virtual void OnNodeCreated() {}
 
    AIMODULE_API void PreSave(FObjectPreSaveContext SaveContext) override;
 
    AIMODULE_API virtual const UObject* GetAssociatedAsset(TOptional<FBehaviorTreeNodeDebugContext> DebugContext) const;
#endif
 
    virtual void SetOwner(AActor* ActorOwner) {}
 
    // BEGIN IGameplayTaskOwnerInterface
    AIMODULE_API virtual UGameplayTasksComponent* GetGameplayTasksComponent(const UGameplayTask& Task) const override;
    AIMODULE_API virtual AActor* GetGameplayTaskOwner(const UGameplayTask* Task) const override;
    AIMODULE_API virtual AActor* GetGameplayTaskAvatar(const UGameplayTask* Task) const override;
    AIMODULE_API virtual uint8 GetGameplayTaskDefaultPriority() const override;
    AIMODULE_API virtual void OnGameplayTaskInitialized(UGameplayTask& Task) override;
    // END IGameplayTaskOwnerInterface
 
    AIMODULE_API UBehaviorTreeComponent* GetBTComponentForTask(UGameplayTask& Task) const;
    
    template <class T>
    T* NewBTAITask(UBehaviorTreeComponent& BTComponent)
    {
        check(BTComponent.GetAIOwner());
        bOwnsGameplayTasks = true;
        return UAITask::NewAITask<T>(*BTComponent.GetAIOwner(), *this, TEXT("Behavior"));
    }
    
    template <class T>
    T* NewBTAITask(const UClass& Class, UBehaviorTreeComponent& BTComponent)
    {
        check(BTComponent.GetAIOwner());
        bOwnsGameplayTasks = true;
        return UAITask::NewAITask<T>(Class, *BTComponent.GetAIOwner(), *this, TEXT("Behavior"));
    }
 
    UPROPERTY(Category=Description, EditAnywhere)
    FString NodeName;
    
private:
 
    UPROPERTY()
    TObjectPtr<UBehaviorTree> TreeAsset;
 
    UPROPERTY()
    TObjectPtr<UBTCompositeNode> ParentNode;
 
#if USE_BEHAVIORTREE_DEBUGGER
    TWeakObjectPtr<UBTNode> NextExecutionNode;
#endif
 
    UPROPERTY(transient)
    uint16 ExecutionIndex;
 
    UPROPERTY(transient)
    uint16 MemoryOffset;
 
    UPROPERTY(transient)
    uint8 TreeDepth;
 
    UPROPERTY(transient)
    uint8 bIsInstanced : 1;
 
    UPROPERTY(transient)
    uint8 bIsInjected : 1;
 
protected:
 
    UPROPERTY(transient)
    uint8 bCreateNodeInstance : 1;
 
    UPROPERTY(transient)
    uint8 bOwnsGameplayTasks : 1;
};
 
// Inlines
 
inline UBehaviorTree* UBTNode::GetTreeAsset() const
{
    return TreeAsset;
}
 
inline UBTCompositeNode* UBTNode::GetParentNode() const
{
    return ParentNode;
}
 
#if USE_BEHAVIORTREE_DEBUGGER
inline UBTNode* UBTNode::GetNextNode() const
{
    return NextExecutionNode.Get();
}
#endif
 
inline uint16 UBTNode::GetExecutionIndex() const
{
    return ExecutionIndex;
}
 
inline uint16 UBTNode::GetMemoryOffset() const
{
    return MemoryOffset;
}
 
inline uint8 UBTNode::GetTreeDepth() const
{
    return TreeDepth;
}
 
inline void UBTNode::MarkInjectedNode()
{
    bIsInjected = true;
}
 
inline bool UBTNode::IsInjected() const
{
    return bIsInjected;
}
 
inline void UBTNode::ForceInstancing(bool bEnable)
{
    // allow only in not initialized trees, side effect: root node always blocked
    check(ParentNode == NULL);
 
    bCreateNodeInstance = bEnable;
}
 
inline bool UBTNode::HasInstance() const
{
    return bCreateNodeInstance;
}
 
inline bool UBTNode::IsInstanced() const
{
    return bIsInstanced;
}
 
template<typename T>
T* UBTNode::InitializeNodeMemory(uint8* NodeMemory, EBTMemoryInit::Type InitType) const
{
    if (InitType == EBTMemoryInit::Initialize)
    {
        new(NodeMemory) T();
    }
    return CastInstanceNodeMemory<T>(NodeMemory);
}
 
template <typename T>
void UBTNode::CleanupNodeMemory(uint8* NodeMemory, EBTMemoryClear::Type CleanupType) const
{
    if constexpr (!std::is_trivially_destructible_v<T>)
    {
        if (CleanupType == EBTMemoryClear::Destroy)
        {
            CastInstanceNodeMemory<T>(NodeMemory)->~T();
        }
    }
}
 
template<typename T>
T* UBTNode::GetNodeMemory(FBehaviorTreeSearchData& SearchData) const
{
    return GetNodeMemory<T>(SearchData.OwnerComp.InstanceStack[SearchData.OwnerComp.GetActiveInstanceIdx()]);
}
 
template<typename T>
const T* UBTNode::GetNodeMemory(const FBehaviorTreeSearchData& SearchData) const
{
    return GetNodeMemory<T>(SearchData.OwnerComp.InstanceStack[SearchData.OwnerComp.GetActiveInstanceIdx()]);
}
 
template<typename T>
T* UBTNode::GetNodeMemory(FBehaviorTreeInstance& BTInstance) const
{
    return (T*)(BTInstance.GetInstanceMemory().GetData() + MemoryOffset);
}
 
template<typename T>
const T* UBTNode::GetNodeMemory(const FBehaviorTreeInstance& BTInstance) const
{
    return (const T*)(BTInstance.GetInstanceMemory().GetData() + MemoryOffset);
}
 
template<typename T>
T* UBTNode::CastInstanceNodeMemory(uint8* NodeMemory) const
{
    // using '<=' rather than '==' to allow child classes to extend parent's
    // memory class as well (which would make GetInstanceMemorySize return 
    // a value equal or greater to sizeof(T)).
    checkf(sizeof(T) <= GetInstanceMemorySize(), TEXT("Requesting type of %zu bytes but GetInstanceMemorySize returns %u. Make sure GetInstanceMemorySize is implemented properly in %s class hierarchy."), sizeof(T), GetInstanceMemorySize(), *GetFName().ToString());
    return reinterpret_cast<T*>(NodeMemory);
}
 
template<typename T>
T* UBTNode::GetSpecialNodeMemory(uint8* NodeMemory) const
{
    const int32 SpecialMemorySize = GetSpecialMemorySize();
    return SpecialMemorySize ? (T*)(NodeMemory - ((SpecialMemorySize + 3) & ~3)) : nullptr;
}