Unreal Engine 4.26 Documentation

Unreal Engine 4.27 Documentation

Unreal Engine 5.0 Documentation

Unreal Engine 5.1 Documentation

Unreal Engine 5.2 Documentation

Unreal Engine 5.3 Documentation

> Unreal Engine API Reference > Plugins > Niagara > FNiagaraGPUInstanceCountManager

Light Theme

Dark Theme

FNiagaraGPUInstanceCountManager

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

Choose your operating system:

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	AllocatedCulledCounts	The allocated instance counts in the culled count buffer
int32	AllocatedInstanceCounts	The allocated instance counts in CountBuffer
bool	bAcquiredCulledCounts	Whether or not the culled counts were acquired this frame
FRWBuffer	CountBuffer	A buffer holding the each emitter particle count after a simulation tick.
FRHIGPUMemoryRe...	CountReadback
int32	CountReadbackSize
FRWBuffer	CulledCountBuffer
TArray< FNiagar...	DrawIndirectArgGenTasks	The list of all draw indirected tasks that are to be run in UpdateDrawIndirectBuffers()
TMap< FNiagaraD...	DrawIndirectArgMap
uint32	DrawIndirectLowWaterFrames
TArray< FIndire...	DrawIndirectPool	Buffers holding drawindirect data to render GPU emitter renderers.
ERHIFeatureLeve...	FeatureLevel
TArray< uint32 ...	FreeEntries
TArray< uint32 ...	InstanceCountClearTasks	The list of all instance count clear tasks that are to be run in UpdateDrawIndirectBuffers()
int32	RequiredCulledCounts	The number of culled instance counts needed from view culling
int32	UsedInstanceCounts	The current used instance counts allocated from FNiagaraDataBuffer::AllocateGPU()

Constructors

	Name	Description
	FNiagaraGPUInstanceCountManager ( ERHIFeatureLevel::Type FeatureLevel )

Destructors

	Name	Description
	~FNiagaraGPUInstanceCountManager()

Functions

	Name	Description
FRWBuffer &#...	AcquireCulledCountsBuffer ( FRHICommandListImmediate& RHICmdLi... )
uint32	AcquireCulledEntry()
uint32	AcquireEntry()	Acquire an entry from the free list, assumes this comes from being presized.
uint32	AcquireOrAllocateEntry ( FRHICommandListImmediate& RHICmdLi... )	Acquire an entry, this will either come from the free list or reallocate the buffer.
FIndirectArg...	AddDrawIndirect ( uint32 InstanceCountBufferOffset, uint32 NumIndicesPerInstance, uint32 StartIndexLocation, bool bIsInstancedStereoEnabled, bool bCulled, ENiagaraGpuComputeTickStage::Type R... )	Add a draw indirect task to generate the draw indirect args.
bool	CanAcquireCulledEntry()
void	EnqueueGPUReadback ( FRHICommandListImmediate& RHICmdLi... )
void	FlushIndirectArgsPool()
void	FreeEntry ( uint32& BufferOffset )	Free the entry and reset it to INDEX_NONE if valid.
void	FreeEntryArray ( TConstArrayView< uint32 > EntryArra... )	Free and array of entries, you are expected to reset or change to INDEX_NONE.
const uint32...	GetGPUReadback()
const FRWBuf...	GetInstanceCountBuffer()
bool	HasEntriesPendingFree()
bool	HasPendingGPUReadback()
void	InitRHI()	Init resource for the first time.
void	ReleaseCounts()
void	ReleaseGPUReadback()
void	ReleaseRHI()	Free resources.
void	ResizeBuffers ( FRHICommandListImmediate& RHICmdLi..., int32 ReservedInstanceCounts )	Resize instance count and draw indirect buffers to ensure it is big enough to hold all draw indirect args.
void	UpdateDrawIndirectBuffers ( FNiagaraGpuComputeDispatchInterface..., FRHICommandList& RHICmdList, ENiagaraGPUCountUpdatePhase::Type C... )	Generate the draw indirect buffers, and reset all release counts.

Classes

	Name	Description
	FIndirectArgSlot
	FIndirectArgsPoolEntry
	FNiagaraDrawIndirectArgGenSlotInfo	Set to allow de-duplication of FNiagaraDrawIndirectArgGenTaskInfo.

Typedefs

Name	Description
FIndirectArgsPoolEntryPtr

Constants

Name	Description
kCountBufferDefaultState