UImportanceSamplingLibrary::NextSobolCell2D

function Engine Blueprint Since 5.0

#include "Kismet/ImportanceSamplingLibrary.h"

Access: public Specifiers: staticUFUNCTIONBlueprintPure

Description

Advances a 2D Sobol cell sequence to the next point using the previous sample, avoiding recomputation from index 0. Use inside loops that step through consecutive samples in the same grid cell.

Caveats & Gotchas

• PreviousValue must be the actual result returned for Index-1 in the same cell — arbitrary values break the incremental math.
• NumCells must match the value used to produce PreviousValue; changing it mid-sequence invalidates the result.
• Only valid for consecutive indices within a single cell; jumping indices requires RandomSobolCell2D.

Signature

static FVector2D NextSobolCell2D(int32 Index, int32 NumCells = 1, FVector2D PreviousValue = FVector2D(0,0))

Parameters

Name	Type	Description	Default
Index	int32	Which sequential point in the cell (the point being advanced to).	—
NumCells	int32	Size of the cell grid, 1 to 32768. Rounded up to the next power of two.	1
PreviousValue	FVector2D	The Sobol value returned for Index-1 in the same cell.	FVector2D(0,0)

Return Type

FVector2D

Example

Step through samples in a cell C++

FVector2D Point = UImportanceSamplingLibrary::RandomSobolCell2D(0, 8, FVector2D(1,1));
for (int32 i = 1; i < 32; ++i)
{
    Point = UImportanceSamplingLibrary::NextSobolCell2D(i, 8, Point);
}

Version History

Introduced in: 5.0

Version	Status	Notes
5.6	stable	—

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