Tool object used for sampling screen tiles according to estimated pixel variance (used in path tracing engine). To improve GPU thread coherency, rendering window is split into pixel blocks or tiles. The important feature of this approach is that it is possible to keep the same number of tiles for any screen resolution (e.g. 256 tiles can be used for both 512 x 512 window and 1920 x 1080 window). So, a smaller number of tiles allows to increase interactivity (FPS), but at the cost of higher per-frame variance ('noise'). On the contrary a larger number of tiles decrease interactivity, but leads to lower per-frame variance. Note that the total time needed to produce final final image is the same for both cases. More...

#include <OpenGl_TileSampler.hxx>

Public Member Functions
	OpenGl_TileSampler ()
	Creates new tile sampler. More...

int	SizeX () const
	Returns width of ray-tracing viewport. More...

int	SizeY () const
	Returns height of ray-tracing viewport. More...

int	NbTilesX () const
	Returns number of tiles in X dimension. More...

int	NbTilesY () const
	Returns number of tiles in Y dimension. More...

int	NbTiles () const
	Returns total number of tiles in viewport. More...

void	SetSize (const int theSizeX, const int theSizeY)
	Specifies size of ray-tracing viewport. More...

int	TileArea (const int theX, const int theY) const
	Returns number of pixels in the given tile. More...

void	GrabVarianceMap (const Handle< OpenGl_Context > &theContext)
	Fetches current error estimation from the GPU and builds 2D discrete distribution for tile sampling. More...

void	Sample (int &theOffsetX, int &theOffsetY)
	Samples tile location according to estimated error. More...

void	Reset ()
	Resets tile sampler to initial state. More...

void	Upload (const Handle< OpenGl_Context > &theContext, const Handle< OpenGl_Texture > &theTexture, const int theNbTilesX, const int theNbTilesY, const bool theAdaptive)
	Uploads offsets of sampled tiles to the given OpenGL texture. More...

Static Public Member Functions
static int	TileSize ()
	Size of individual tile in pixels. More...

Protected Member Functions
float	Tile (const int theX, const int theY) const
	Returns tile value (estimated error). More...

float &	ChangeTile (const int theX, const int theY)
	Returns tile value (estimated error). More...

Protected Attributes
std::vector< float >	myVarianceMap
	Estimation of visual error per tile. More...

std::vector< float >	myMarginalMap
	Marginal distribution of 2D error map. More...

OpenGl_HaltonSampler	mySampler
	Halton sequence generator. More...

int	mySample
	Index of generated sample. More...

int	mySizeX
	Width of ray-tracing viewport. More...

int	mySizeY
	Height of ray-tracing viewport. More...

int	myTilesX
	Number of tiles in X dimension. More...

int	myTilesY
	Number of tiles in Y dimension. More...

Detailed Description

Tool object used for sampling screen tiles according to estimated pixel variance (used in path tracing engine). To improve GPU thread coherency, rendering window is split into pixel blocks or tiles. The important feature of this approach is that it is possible to keep the same number of tiles for any screen resolution (e.g. 256 tiles can be used for both 512 x 512 window and 1920 x 1080 window). So, a smaller number of tiles allows to increase interactivity (FPS), but at the cost of higher per-frame variance ('noise'). On the contrary a larger number of tiles decrease interactivity, but leads to lower per-frame variance. Note that the total time needed to produce final final image is the same for both cases.

Constructor & Destructor Documentation

◆ OpenGl_TileSampler()

OpenGl_TileSampler::OpenGl_TileSampler ( )

Creates new tile sampler.

Member Function Documentation

◆ ChangeTile()

float& OpenGl_TileSampler::ChangeTile	(	const int	theX,
		const int	theY
	)

inlineprotected

Returns tile value (estimated error).

◆ GrabVarianceMap()

void OpenGl_TileSampler::GrabVarianceMap ( const Handle< OpenGl_Context > & theContext )

Fetches current error estimation from the GPU and builds 2D discrete distribution for tile sampling.

◆ NbTiles()

int OpenGl_TileSampler::NbTiles ( ) const

inline

Returns total number of tiles in viewport.

◆ NbTilesX()

int OpenGl_TileSampler::NbTilesX ( ) const

inline

Returns number of tiles in X dimension.

◆ NbTilesY()

int OpenGl_TileSampler::NbTilesY ( ) const

inline

Returns number of tiles in Y dimension.

◆ Reset()

void OpenGl_TileSampler::Reset ( void )

inline

Resets tile sampler to initial state.

◆ Sample()

void OpenGl_TileSampler::Sample	(	int &	theOffsetX,
		int &	theOffsetY
	)

Samples tile location according to estimated error.

◆ SetSize()

void OpenGl_TileSampler::SetSize	(	const int	theSizeX,
		const int	theSizeY
	)

Specifies size of ray-tracing viewport.

◆ SizeX()

int OpenGl_TileSampler::SizeX ( ) const

inline

Returns width of ray-tracing viewport.

◆ SizeY()

int OpenGl_TileSampler::SizeY ( ) const

inline

Returns height of ray-tracing viewport.

◆ Tile()

float OpenGl_TileSampler::Tile	(	const int	theX,
		const int	theY
	)		const

inlineprotected

Returns tile value (estimated error).

◆ TileArea()

int OpenGl_TileSampler::TileArea	(	const int	theX,
		const int	theY
	)		const

inline

Returns number of pixels in the given tile.

◆ TileSize()

static int OpenGl_TileSampler::TileSize ( )

inlinestatic

Size of individual tile in pixels.

◆ Upload()

void OpenGl_TileSampler::Upload	(	const Handle< OpenGl_Context > &	theContext,
		const Handle< OpenGl_Texture > &	theTexture,
		const int	theNbTilesX,
		const int	theNbTilesY,
		const bool	theAdaptive
	)

Uploads offsets of sampled tiles to the given OpenGL texture.

Field Documentation

◆ myMarginalMap

std::vector<float> OpenGl_TileSampler::myMarginalMap

protected

Marginal distribution of 2D error map.

◆ mySample

int OpenGl_TileSampler::mySample

protected

Index of generated sample.

◆ mySampler

OpenGl_HaltonSampler OpenGl_TileSampler::mySampler

protected

Halton sequence generator.

◆ mySizeX

int OpenGl_TileSampler::mySizeX

protected

Width of ray-tracing viewport.

◆ mySizeY

int OpenGl_TileSampler::mySizeY

protected

Height of ray-tracing viewport.

◆ myTilesX

int OpenGl_TileSampler::myTilesX

protected

Number of tiles in X dimension.

◆ myTilesY

int OpenGl_TileSampler::myTilesY

protected

Number of tiles in Y dimension.

◆ myVarianceMap

std::vector<float> OpenGl_TileSampler::myVarianceMap

protected

Estimation of visual error per tile.

The documentation for this class was generated from the following file:

OpenGl_TileSampler.hxx

OpenGl_TileSampler Class Reference

Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ OpenGl_TileSampler()

Member Function Documentation

◆ ChangeTile()

◆ GrabVarianceMap()

◆ NbTiles()

◆ NbTilesX()

◆ NbTilesY()

◆ Reset()

◆ Sample()

◆ SetSize()

◆ SizeX()

◆ SizeY()

◆ Tile()

◆ TileArea()

◆ TileSize()

◆ Upload()

Field Documentation

◆ myMarginalMap

◆ mySample

◆ mySampler

◆ mySizeX

◆ mySizeY

◆ myTilesX

◆ myTilesY

◆ myVarianceMap