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  3. FInstanceAttributeTracker

FInstanceAttributeTracker

Tracks changes for instances, but that assumes storing stuff per index except the removed status which must be kept ID-based Removed items are tracked by ID and kept separate as we need to remember if an item was ever removed in order to handle these correctly.

API > API/Runtime > API/Runtime/Engine

Tracks changes for instances, but that assumes storing stuff per index except the removed status which must be kept ID-based Removed items are tracked by ID and kept separate as we need to remember if an item was ever removed in order to handle these correctly. Designed to use move semantics to clear the state and transfer to the updating worker task.

   
Name FInstanceAttributeTracker
Type class
Header File /Engine/Source/Runtime/Engine/Public/InstancedStaticMesh/InstanceAttributeTracker.h
Include Path #include "InstancedStaticMesh/InstanceAttributeTracker.h"

Syntax

class FInstanceAttributeTracker

Constructors

Name Remarks Include Path Unreal Specifiers
  InstancedStaticMesh/InstanceAttributeTracker.h  
  InstancedStaticMesh/InstanceAttributeTracker.h  

Classes

Name Remarks
FAnyValidIterator Iterator for iterating tracked state with the given flags.
FDeltaRange Represents the delta range for a given attribute, can either refer to the tracked data or just a span, or be empty.

Structs

Name Remarks
FToBit Helper struct to convert the flag to its bitmask at comile time.

Enums

Public

Name Remarks
EFlag Flag describing the changed attribute. Note that not all are created equal, see comments.

Typedefs

Name Type Remarks Include Path
ElementType uint32 Underlying type to store per-instance masks packed in. For example, with EFlag::Num == 4, and uint32 we can store 8 masks in each element. InstancedStaticMesh/InstanceAttributeTracker.h
FBitManip UE::InstanceAttributeTracker::Implementation::FBitManip< ElementType >   InstancedStaticMesh/InstanceAttributeTracker.h

Constants

Name Type Remarks Include Path
AddedElementMask ElementType   InstancedStaticMesh/InstanceAttributeTracker.h
AnyFlagMask ElementType   InstancedStaticMesh/InstanceAttributeTracker.h
BitsPerElement uint32   InstancedStaticMesh/InstanceAttributeTracker.h
IndexChangedElementMask ElementType Masks replicated to all masks that fit inside ElementType InstancedStaticMesh/InstanceAttributeTracker.h
MasksPerElement int32   InstancedStaticMesh/InstanceAttributeTracker.h

Variables

Protected

Name Type Remarks Include Path Unreal Specifiers
Data TArray< ElementType > Data for packed per-instance change attribute mask. InstancedStaticMesh/InstanceAttributeTracker.h  
FirstChangedIndex int32 Tracks the first & last mask with any change flag set InstancedStaticMesh/InstanceAttributeTracker.h  
FirstRemovedIdIndex int32 Tracks the index of the first non-zero bit in the Removed bitvector. InstancedStaticMesh/InstanceAttributeTracker.h  
LastChangedIndex int32   InstancedStaticMesh/InstanceAttributeTracker.h  
MaxIndex int32 Maximum valid index. InstancedStaticMesh/InstanceAttributeTracker.h  
NumChanged int32 Tracks the number of changes for each attribute in such a way that NumChanged[Added] + NumChanged[OtherAttribute] is the total number we need to copy over. InstancedStaticMesh/InstanceAttributeTracker.h  
Removed TBitArray Removed items are tracked by ID and kept separate as we need to remember if an item was ever removed in order to handle these correctly. InstancedStaticMesh/InstanceAttributeTracker.h  

Functions

Public

Name Remarks Include Path Unreal Specifiers

SIZE_T GetAllocatedSize()

   InstancedStaticMesh/InstanceAttributeTracker.h  

FAnyValidIterator< Mask > GetChangedIterator()

   InstancedStaticMesh/InstanceAttributeTracker.h  

FDeltaRange< Flag > GetDeltaRange ( bool bForceFullUpdate,
int32 InNumItems
) const

   InstancedStaticMesh/InstanceAttributeTracker.h  

ElementType GetFlags ( int32 Index
) const

 Get the masked flags for a given index. InstancedStaticMesh/InstanceAttributeTracker.h  
Get an iterator that iterates over the IDs (note, not index as they don't exist any more) of removed instances. InstancedStaticMesh/InstanceAttributeTracker.h  

bool HasAnyChanges()

   InstancedStaticMesh/InstanceAttributeTracker.h  

void MarkIndex ( int32 Index,
int32 MaxInstanceIndex
)

   InstancedStaticMesh/InstanceAttributeTracker.h  
Lazy allocate bits in the bit vector tracking removed instances and set the flag for the instance ID. InstancedStaticMesh/InstanceAttributeTracker.h  

void RemoveAt ( FPrimitiveInstanceId Id,
int32 Index,
int32 MaxInstanceIndex
)

 Mark removed & update the tracked bits (remove & move operation) Note: this is not something that should be used really as it forces the tracker to touch all the masks after the removed item... InstancedStaticMesh/InstanceAttributeTracker.h  

void RemoveAtSwap ( FPrimitiveInstanceId Id,
int32 Index,
int32 MaxInstanceIndex
)

 Mark removed & update the tracked bits (remove & swap operation) InstancedStaticMesh/InstanceAttributeTracker.h  

void Reset()

   InstancedStaticMesh/InstanceAttributeTracker.h  

void SetNum ( int32 InstanceIndexMax
)

   InstancedStaticMesh/InstanceAttributeTracker.h  

bool TestFlag ( int32 Index
) const

 Test a specific flag at a given index. InstancedStaticMesh/InstanceAttributeTracker.h  

void Validate()

   InstancedStaticMesh/InstanceAttributeTracker.h  

Static

Name Remarks Include Path Unreal Specifiers

static void Move ( FInstanceAttributeTracker& Dest,
FInstanceAttributeTracker& Source
)

   InstancedStaticMesh/InstanceAttributeTracker.h  

Operators

Name Remarks Include Path Unreal Specifiers

void operator= ( FInstanceAttributeTracker&& Other
)

   InstancedStaticMesh/InstanceAttributeTracker.h  

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