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  3. FRDGBuilderRecorder

FRDGBuilderRecorder

This struct is usually meant to be allocated on the game thread (where there's no FRDGBuilder, which is Render Thread-only) and allows to queue successive operations (lambdas) onto a single render command, sharing the same FRDGBuilder.

API > API/Runtime > API/Runtime/Landscape

This struct is usually meant to be allocated on the game thread (where there's no FRDGBuilder, which is Render Thread-only) and allows to queue successive operations (lambdas) onto a single render command, sharing the same FRDGBuilder. This allows to sequence a list of RDG passes from the game thread and makes it possible to interleave render thread operations (in a single render command) with game thread-initiated render commands. Here's an extensive use case :

FRDGBuilderRecorder Recorder;

// Start recording commands to a single graph builder : Recorder.StartRecording();

Recorder.EnqueueRDGCommand( { GraphBuilder->AddPass(); }); // Append a Pass_A ENQUEUE_RENDER_COMMAND(...) // Push Render_Command_A (immediately) Recorder.EnqueueRDGCommand( { GraphBuilder->AddPass(); }, { { SomeTexture, ERHIAccess::RTV } }); // Append a Pass_B and inform of the final state of a given texture to prevent the RDG from auto-transitioning to SRVMask at the end Recorder.EnqueueRenderCommand(FRHICommandListImmediate& InRHICmdList mutable { [...]; }); // Append a Render_Command_B to the graph builder Recorder.EnqueueRDGCommand( { GraphBuilder->AddPass(); }, { { }SomeTexture, ERHIAccess::CopySrc } }); // Append a Pass_C and inform of the final state of a given texture to prevent the RDG from auto-transitioning to SRVMask at the end

// Stop recording and issue a render command with all that's been recorded so far Recorder.StopRecordingAndFlush(RDG_EVENT_NAME("Pass ABC"));

// Enqueue some game-thread render commands (e.g. BP render) either directly or via the recorder in immediate mode : ENQUEUE_RENDER_COMMAND(...) // Render_Command_C Recorder.EnqueueRDGCommand( { GraphBuilder->AddPass(); }, { { SomeTexture, ERHIAccess::CopyDst } }); // Append a Pass_D and inform of the final state of a given texture to prevent the RDG from auto-transitioning to SRVMask at the end Recorder.EnqueueRenderCommand(RHIOperation mutable { [...]; }); // Append a Render_Command_D

// Start recording commands again to a new single graph builder : Recorder.StartRecording(); Recorder.EnqueueRDGCommand( { GraphBuilder->AddPass(); }); // Append a Pass_E

// Stop recording and issue a render command with all that's been recorded so far Recorder.StopRecordingAndFlush(RDG_EVENT_NAME("Pass E"));

--> Will yield the following sequence on the render thread:
  • Render_Command_A
  • Render Command "Pass ABC" +- (RDGBuilder_0) +- RDGBuilder_0.Pass_A +- RDGBuilder_0.Pass_B +- RDGBuilder_0.LambdaPass (Render_Command_B) +- RDGBuilder_0.Pass_C +- RDGBuilder_0.SetTextureAccessFinal(OutputTexture, ERHIAccess::CopySrc); // Only the final state recorded for a given texture is set +- RDGBuilder_0.Execute
  • Render_Command_C
  • Render Command +- (RDGBuilder_1) +- RDGBuilder_1.Pass_D +- RDGBuilder_1.SetTextureAccessFinal(OutputTexture, ERHIAccess::CopyDst); +- RDGBuilder_1.Execute
  • Render_Command_D
  • Render Command "Pass E" +- (RDGBuilder_2) +- RDGBuilder_2.Pass_E +- RDGBuilder_2.Execute
   
Name FRDGBuilderRecorder
Type class
Header File /Engine/Source/Runtime/Landscape/Public/LandscapeUtils.h
Include Path #include "LandscapeUtils.h"

Syntax

class FRDGBuilderRecorder

Constructors

Name Remarks Include Path Unreal Specifiers

FRDGBuilderRecorder()

   LandscapeUtils.h  

Destructors

Name Remarks Include Path Unreal Specifiers

~FRDGBuilderRecorder()

   LandscapeUtils.h  

Structs

Name Remarks
FRDGExternalTextureAccessFinal  

Enums

Public

Name Remarks
EState  

Typedefs

Name Type Remarks Include Path
FRDGRecorderRDGCommand TFunction< void(FRDGBuilder &)>   LandscapeUtils.h
FRDGRecorderRenderCommand TFunction< void(FRHICommandListImmediate &)>   LandscapeUtils.h

Variables

Protected

Name Type Remarks Include Path Unreal Specifiers
RDGCommands TArray< FRDGRecorderRDGCommand > List of callbacks to call on the render thread after the render command was initiated. LandscapeUtils.h  
RDGExternalTextureAccessFinal TMap< FTextureResource *, ERHIAccess > Map of textures and the RHI access they should have when leaving the FRDGBuilder : LandscapeUtils.h  
State EState   LandscapeUtils.h  

Functions

Public

Name Remarks Include Path Unreal Specifiers

void Clear ()

 Cancels all recorder operations. LandscapeUtils.h  

void EnqueueRDGCommand ( FRDGRecorderRDGCommand InRDGCommand,
TConstArrayView< FRDGExternalTextureAccessFinal > InRDGExternalTextureAccessFinalList
)

 Records a FRDGRecorderRDGCommand to execute when registering passes to the single FRDGBuilder when in Recording mode or pushes it immediately to the render thread when in Immediate mode LandscapeUtils.h  

void EnqueueRenderCommand ( FRDGRecorderRenderCommand InRenderCommand
)

 Records a FRDGRecorderRenderCommand to execute when registering passes to the single FRDGBuilder when in Recording mode or pushes it immediately to the render thread when in Immediate mode LandscapeUtils.h  

void Flush ( FRDGEventName&& EventName
)

 Flushes any pending command to the render thread LandscapeUtils.h  

EState GetState()

   LandscapeUtils.h  

bool IsEmpty()

   LandscapeUtils.h  

bool IsRecording()

   LandscapeUtils.h  

void StartRecording()

 Starts recording commands LandscapeUtils.h  

void StopRecording ()

 Stops recording commands. LandscapeUtils.h  

void StopRecordingAndFlush ( FRDGEventName&& EventName
)

 Stops recording commands and flushes them to the render thread. LandscapeUtils.h  

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