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> Unreal Engine API Reference > Plugins > MovieRenderPipelineCore > FMoviePipelineSurfaceReader

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FMoviePipelineSurfaceReader

Copyright Epic Games, Inc. All Rights Reserved.

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References

Module	MovieRenderPipelineCore
Header	/Engine/Plugins/MovieScene/MovieRenderPipeline/Source/MovieRenderPipelineCore/Public/MoviePipelineSurfaceReader.h
Include	#include "MoviePipelineSurfaceReader.h"

Syntax

struct FMoviePipelineSurfaceReader

Remarks

When the GPU finishes rendering a view we can copy the resulting data back to the CPU. Because the buffer is still in use this requires flushing the RHI and stalling the GPU from doing any additional work while the copy is in progress. To resolve this issue, when the data is returned we schedule a copy to a surface that isn't in use which allows the GPU to resume work. Then when the surface is written to, we can copy it to the CPU without blocking the GPU. This requires ensuring that the surface is available, so this SurfaceReader implements a trigger system to ensure we don't try to access the surface until it has been written to, combined with a round-robin of surfaces to avoid stalls.

Variables

	Name	Description
FEvent *	AvailableEvent	Optional event that is triggered when the surface is no longer in use
bool	bQueuedForCapture
EPixelFormat	PixelFormat	The desired pixel format of the resolved textures
FTexture2DRHIRe...	ReadbackTexture	Texture used to store the resolved render target

Constructors

	Name	Description
	FMoviePipelineSurfaceReader ( EPixelFormat InPixelFormat, FIntPoint InSurfaceSize )	Construct a surface reader with the given pixel format and size.

Destructors

	Name	Description
	~FMoviePipelineSurfaceReader()

Functions

	Name	Description
void	BlockUntilAvailable()	Wait until this surface is available for reuse.
void	CopyReadbackTexture_RenderThread ( const FMoviePipelineRenderPassMetri..., const FMoviePipelineSampleReady& I... )	Maps the ReadbackTexture to the CPU (which should have been resolved to before this point) and copies the data over.
void	Initialize()	Initialize this reader so that it can be waited on.
bool	IsAvailable()
void	Reset()	Safely resets the state of the wait event.
void	Resize ( uint32 Width, uint32 Height )	Set up this surface to the specified width/height
void	ResolveSampleToReadbackTexture_RenderThread ( const FTexture2DRHIRef& SourceSurf... )	Issues a command to the GPU to copy the given SourceSurfaceSample to our local ReadbackTexture for this surface.
bool	WasEverQueued()

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