FRDGBlackboard | Unreal Engine 5.6 Documentation

API > API/Runtime > API/Runtime/RenderCore

The blackboard is a map of struct instances with a lifetime tied to a render graph allocator. It is designed to solve cases where explicit marshaling of immutable data is undesirable. Structures are created once and the mutable reference is returned.

Good candidates for the blackboard would be data that is created once and immutably fetched across the entire renderer pipeline, where marshaling would create more maintenance burden than benefit. More constrained data structures should be marshaled through function calls instead.

Example of Usage:

class FMyStruct { public: FRDGTextureRef TextureA = nullptr; FRDGTextureRef TextureB = nullptr; FRDGTextureRef TextureC = nullptr; };

RDG_REGISTER_BLACKBOARD_STRUCT(FMyStruct);

static void InitStruct(FRDGBlackboard& GraphBlackboard) { auto& MyStruct = GraphBlackboard.Create();

//... }

static void UseStruct(const FRDGBlackboard& GraphBlackboard) { const auto& MyStruct = GraphBlackboard.GetChecked();

//... }


Name	FRDGBlackboard
Type	class
Header File	/Engine/Source/Runtime/RenderCore/Public/RenderGraphBlackboard.h
Include Path	#include "RenderGraphBlackboard.h"

Syntax

class FRDGBlackboard

Constructors

Name	Remarks	Include Path	Unreal Specifiers
FRDGBlackboard ( FRDGAllocator& InAllocator )		RenderGraphBlackboard.h

Structs

Name	Remarks
FStruct
TStruct

Variables

Protected

Name	Type	Remarks	Include Path	Unreal Specifiers
Allocator	FRDGAllocator &		RenderGraphBlackboard.h
Blackboard	TArray< FStruct *, FRDGArrayAllocator >		RenderGraphBlackboard.h

Functions

Public

Name	Remarks	Include Path
StructType & Create ( ArgsType&&... Args )	Creates a new instance of a struct. Asserts if one already existed.	RenderGraphBlackboard.h
const StructType * Get()	Gets an immutable instance of the struct. Returns null if not present in the blackboard.	RenderGraphBlackboard.h
const StructType & GetChecked()	Gets an immutable instance of the struct. Asserts if not present in the blackboard.	RenderGraphBlackboard.h
StructType * GetMutable()	Gets a mutable instance of the struct. Returns null if not present in the blackboard.	RenderGraphBlackboard.h
StructType & GetMutableChecked()	Gets a mutable instance of the struct. Asserts if not present in the blackboard.	RenderGraphBlackboard.h
StructType & GetOrCreate ( ArgsType&&... Args )		RenderGraphBlackboard.h

Static

Name	Remarks	Include Path	Unreal Specifiers
static uint32 AllocateIndex ( FString&& TypeName )		RenderGraphBlackboard.h
static uint32 GetStructIndex()		RenderGraphBlackboard.h
static FString GetTypeName ()		RenderGraphBlackboard.h
static FString GetTypeName ( const TCHAR* ClassName, const TCHAR* FileName, uint32 LineNumber )		RenderGraphBlackboard.h

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