ImportanceSampling Namespace Reference

Functions
Math|Random
FVector	NextSobolCell3D (int Index, int NumCells=1, FVector PreviousValue=FVector(0.000000, 0.000000, 0.000000))
void	ImportanceSample (FImportanceTexture Texture, FVector2D Rand, int Samples, float32 Intensity, FVector2D &SamplePosition, FLinearColor &SampleColor, float32 &SampleIntensity, float32 &SampleSize)
	Distribute sample points proportional to Texture2D luminance.
FImportanceTexture	MakeImportanceTexture (UTexture2D Texture, EImportanceWeight WeightingFunc)
	Create an FImportanceTexture object for texture-driven importance sampling from a 2D RGBA8 texture.
FVector2D	NextSobolCell2D (int Index, int NumCells=1, FVector2D PreviousValue=FVector2D(0.000000, 0.000000))
void	BreakImportanceTexture (FImportanceTexture ImportanceTexture, UTexture2D &Texture, EImportanceWeight &WeightingFunc)
	Get texture used to create an ImportanceTexture object.
float32	NextSobolFloat (int Index, int Dimension, float32 PreviousValue)
FVector2D	RandomSobolCell2D (int Index, int NumCells=1, FVector2D Cell=FVector2D(0.000000, 0.000000), FVector2D Seed=FVector2D(0.000000, 0.000000))
FVector	RandomSobolCell3D (int Index, int NumCells=1, FVector Cell=FVector(0.000000, 0.000000, 0.000000), FVector Seed=FVector(0.000000, 0.000000, 0.000000))
float32	RandomSobolFloat (int Index, int Dimension, float32 Seed)

Function Documentation

BreakImportanceTexture()

void BreakImportanceTexture	(	FImportanceTexture	ImportanceTexture,
		UTexture2D &	Texture,
		EImportanceWeight &	WeightingFunc )

Get texture used to create an ImportanceTexture object.

Parameters

ImportanceTexture	The source ImportanceTexture object
WeightingFunc	How to turn the texture data into probability weights

Returns

new ImportanceTexture object for use with ImportanceSample

ImportanceSample()

void ImportanceSample	(	FImportanceTexture	Texture,
		FVector2D	Rand,
		int	Samples,
		float32	Intensity,
		FVector2D &	SamplePosition,
		FLinearColor &	SampleColor,
		float32 &	SampleIntensity,
		float32 &	SampleSize )

Distribute sample points proportional to Texture2D luminance.

Parameters

Rand	Random 2D point with components evenly distributed between 0 and 1
Samples	Total number of samples that will be used
Intensity	Total intensity for light

MakeImportanceTexture()

FImportanceTexture MakeImportanceTexture	(	UTexture2D	Texture,
		EImportanceWeight	WeightingFunc )

Create an FImportanceTexture object for texture-driven importance sampling from a 2D RGBA8 texture.

Parameters

Texture	Texture object to use. Must be RGBA8 format.
WeightingFunc	How to turn the texture data into probability weights

Returns

new ImportanceTexture object for use with ImportanceSample

NextSobolCell2D()

FVector2D NextSobolCell2D	(	int	Index,
		int	NumCells = 1,
		FVector2D	PreviousValue = FVector2D ( 0.000000 , 0.000000 ) )

Parameters

Index	Which sequential point
NumCells	Size of cell grid, 1 to 32768. Rounded up to the next power of two
PreviousValue	The Sobol value for Index-1

Returns

Sobol-distributed random 2D position in the same grid cell

NextSobolCell3D()

FVector NextSobolCell3D	(	int	Index,
		int	NumCells = 1,
		FVector	PreviousValue = FVector ( 0.000000 , 0.000000 , 0.000000 ) )

Parameters

Index	Which sequential point
NumCells	Size of cell grid, 1 to 1024. Rounded up to the next power of two
PreviousValue	The Sobol value for Index-1

Returns

Sobol-distributed random 3D position in the same grid cell

NextSobolFloat()

float32 NextSobolFloat	(	int	Index,
		int	Dimension,
		float32	PreviousValue )

Parameters

Index	Which sequential point
Dimension	Which Sobol dimension (0 to 15)
PreviousValue	The Sobol value for Index-1

Returns

Sobol-distributed random number between 0 and 1

RandomSobolCell2D()

FVector2D RandomSobolCell2D	(	int	Index,
		int	NumCells = 1,
		FVector2D	Cell = FVector2D ( 0.000000 , 0.000000 ),
		FVector2D	Seed = FVector2D ( 0.000000 , 0.000000 ) )

Parameters

Index	Which sequential point in the cell (starting at 0)
NumCells	Size of cell grid, 1 to 32768. Rounded up to the next power of two
Cell	Give a point from this integer grid cell
Seed	Random 2D seed (components in the range 0-1) to randomize across multiple sequences

Returns

Sobol-distributed random 2D position in the given grid cell

RandomSobolCell3D()

FVector RandomSobolCell3D	(	int	Index,
		int	NumCells = 1,
		FVector	Cell = FVector ( 0.000000 , 0.000000 , 0.000000 ),
		FVector	Seed = FVector ( 0.000000 , 0.000000 , 0.000000 ) )

Parameters

Index	Which sequential point in the cell (starting at 0)
NumCells	Size of cell grid, 1 to 1024. Rounded up to the next power of two
Cell	Give a point from this integer grid cell
Seed	Random 3D seed (components in the range 0-1) to randomize across multiple sequences

Returns

Sobol-distributed random 3D vector in the given grid cell

RandomSobolFloat()

float32 RandomSobolFloat	(	int	Index,
		int	Dimension,
		float32	Seed )

Parameters

Index	Which sequential point
Dimension	Which Sobol dimension (0 to 15)
Seed	Random seed (in the range 0-1) to randomize across multiple sequences

Returns

Sobol-distributed random number between 0 and 1