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> Unreal Engine API Reference > Plugins > Niagara > FNiagaraGPUInstanceCountManager

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FNiagaraGPUInstanceCountManager

A manager that handles the buffer containing the GPU particle count.

Windows

MacOS

Linux

References

Module	Niagara
Header	/Engine/Plugins/FX/Niagara/Source/Niagara/Classes/NiagaraGPUInstanceCountManager.h
Include	#include "NiagaraGPUInstanceCountManager.h"

Syntax

class FNiagaraGPUInstanceCountManager

Remarks

A manager that handles the buffer containing the GPU particle count. Also provides related functionalities like the generation of the draw indirect buffer.

Variables

	Name	Description
int32	AllocatedDrawIndirectArgs	The allocated indirect args in DrawIndirectBuffer (each being 5 uint32)
int32	AllocatedInstanceCounts	The allocated instance counts in CountBuffer
float	BufferSlack	Buffer slack size hysteresis used to managed the size of CountBuffer and DrawIndirectBuffer.
FRWBuffer	CountBuffer	A buffer holding the each emitter particle count after a simulation tick.
FRHIGPUMemoryRe...	CountReadback
int32	CountReadbackSize
TArray< FArgGen...	DrawIndirectArgGenTasks
TMap< FArgGenTa...	DrawIndirectArgMap	The map between each task FArgGenTaskInfo and entry offset from DrawIndirectArgGenTasks.
FRWBuffer	DrawIndirectBuffer	A buffer holding drawindirect data to render GPU emitter renderers.
TArray< uint32 ...	FreeEntries
TArray< uint32 ...	InstanceCountClearTasks	The list of all instance count clear tasks that are to be run in UpdateDrawIndirectBuffer()
TRefCountPtr< F...	NumRegisteredGPURenderers	The number of GPU renderer. It defines the max possible required draw indirect args count
int32	UsedInstanceCounts	The current used instance counts allocated from FNiagaraDataBuffer::AllocateGPU()

Constructors

	Name	Description
	FNiagaraGPUInstanceCountManager()

Destructors

	Name	Description
	~FNiagaraGPUInstanceCountManager()

Functions

	Name	Description
uint32	AcquireEntry()
uint32	AddDrawIndirect ( uint32 InstanceCountBufferOffset, uint32 NumIndicesPerInstance, uint32 StartIndexLocation )	Add a draw indirect task to generate the draw indirect args.
void	EnqueueGPUReadback ( FRHICommandListImmediate& RHICmdLi... )
void	FreeEntry ( uint32& BufferOffset )	Free the entry and reset it to INDEX_NONE if valid.
FRWBuffer &	GetDrawIndirectBuffer()
const uint32...	GetGPUReadback()
const TRefCo...	GetGPURendererCount()	Update the max possible required draw indirect args (one per renderer).
FRWBuffer &	GetInstanceCountBuffer()
bool	HasPendingGPUReadback()
void	InitRHI()	Init resource for the first time.
void	ReleaseGPUReadback()
void	ReleaseRHI()	Free resources.
void	ResizeBuffers ( FRHICommandListImmediate& RHICmdLi..., ERHIFeatureLevel::Type FeatureLevel, int32 ReservedInstanceCounts )	Resize instance count and draw indirect buffers to ensure it is big enough to hold all draw indirect args.
void	UpdateDrawIndirectBuffer ( FRHICommandList& RHICmdList, ERHIFeatureLevel::Type FeatureLevel )	Generate the draw indirect buffers, and reset all release counts.

Typedefs

Name	Description
FArgGenTaskInfo	The list of all draw indirected tasks that are to be run in UpdateDrawIndirectBuffer()

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