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  3. FMovieSceneNumericVariant

FMovieSceneNumericVariant

A variant type that masquerades as a numeric (double) value.

API > API/Runtime > API/Runtime/MovieScene > API/Runtime/MovieScene/Variants

References

   
Module MovieScene
Header /Engine/Source/Runtime/MovieScene/Public/Variants/MovieSceneNumericVariant.h
Include #include "Variants/MovieSceneNumericVariant.h"

Syntax

USTRUCT (BlueprintType )  
struct FMovieSceneNumericVariant

Remarks

A variant type that masquerades as a numeric (double) value.

This type is 8 bytes (sizeof(double)) and uses a technique called NaN-boxing to encode variants into those 8-bytes, while a literal double value maintains the exact same bits in-memory as a double. By default this variant can only represent a double, or a UMovieSceneNumericVariantGetter*, but additional variant types can be encoded by deriving from this type and associating type 'IDs' to typed-data (upto 48 bit in size), where the type bits are encoded into the nan bits of the double.

Extensive reading around NaN-boxing techniques can be found elsewhere.

UMovieSceneNumericVariantGetter may be used to assign an external, dynamic value to this variant.

The benefit of using this technique is that this type can be used as a drop-in replacement for any double member variable to provide it with dynamic getter functionality without inflating the size of the class, and with barely any runtime overhead whatsoever. Automatic UPROPERTY upgrade exists for all numeric property types that make sense: int64 and uint64 are not supported in this variant due to loss of precision (doubles only have 52 bits of mantissa)

Constructors

  Type Name Description
Public function   Default constructor - initializes this variant to a value of 0.0
Public function   No init constructor that leaves the underlying memory uninitialized
Public function  

FMovieSceneNumericVariant ( double InValue
)

 Initialize this variant to an explicit literal value
Public function   Initialize this variant to an object pointer that provides a value
Public function   Move-assign and constructible

Functions

  Type Name Description
Public function void

AddStructReferencedObjects ( FReferenceCollector& Collector
)

  
Public function Const FMovieSceneNumericVariant

DeepCopy ( UObject* NewOuter
)

 Make a deep copy of this variant by duplicating the underlying UMovieSceneNumericVariantGetter into a new outer if necessary.
Public function Const bool

ExportTextItem ( FString& ValueStr,
const FMovieSceneNumericVariant& DefaultValue,
UObject* Parent,
int32 PortFlags,
UObject* ExportRootScope
)

  
Public function Const double

Get ()

 Retrieve this variant's numeric value
Public function Const UMovieSceneNumericVariantGetter * Retrieves this variant as a UMovieSceneNumericVariantGetter pointer.
Public function Const double Retrieves this variant as a literal double representation.
Public function Const float Retrieves this variant as a literal double representation, clamped to the range of a float.
Public function void

GetPreloadDependencies ( TArray< UObject* >& OutDeps
)

  
Public function Const uint8 Retrieve the type flags for this variant.
Public function Const bool

Identical ( const FMovieSceneNumericVariant* Other,
uint32 PortFlags
)

  
Public function bool

ImportTextItem ( const TCHAR*& Buffer,
int32 PortFlags,
UObject* Parent,
FOutputDevice* ErrorText,
FArchive* InSerializingArchive
)

  
Public function Const bool Checks whether this variant is a UMovieSceneNumericVariantGetter pointer (ie, GetCustomPtr is valid to call).
Public function Const bool Checks whether this variant is a literal double value or a different type
Public function bool

Serialize ( FArchive& Ar
)

 For StructOpsTypeTraits
Public function bool

SerializeCustom ( FArchive& Ar,
TFunctionRef< void(FArchive&, uint8&, void*)>
)

  
Public function bool

SerializeFromMismatchedTag ( const FPropertyTag& Tag,
FStructuredArchive::FSlot Slot
)

  
Public function void

Set ( double InLiteralValue
)

 Assign a new literal value to this variant, clearing any knowledge of a previously assigned value.
Public function void

Set ( UMovieSceneNumericVariantGetter* InDynamicValue
)

 Assign a new dynamic value to this variant.
Public function void

SetTypeBits ( uint8 InType
)

 Set the type flags for this variant - should only be used where custom typed data is assigned
Public function void

SetTypedData ( const T& InValue,
uint8 InType
)

 Assign new, implementation defined typed data to this variant.
Public function Const FMovieSceneNumericVariant Make a shallow (bitwise) copy of this variant.
Public function Const T Cast this variant to a user-defined type.

Operators

  Type Name Description
Public function FMovieSceneNumericVariant &  

Constants

Name Description
EXP_Bits  
HIGH_Bits Flags specifying different regions on an IEEE 754 double.
PAYLOAD_Bits  
QUIET_Bit  
SIGN_Bit  
TAGGED_Bits  
TYPE_Bits  
TYPE_CustomPtr  

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