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.

Graphic3d_Vec2i	TileSize () const
	Size of individual tile in pixels.

float	VarianceScaleFactor () const
	Scale factor for quantization of visual error (float) into signed integer.

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

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

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

const Graphic3d_Vec2i &	ViewSize () const
	Returns ray-tracing viewport.

Graphic3d_Vec2i	NbOffsetTiles (bool theAdaptive) const
	Number of tiles within offsets texture.

Graphic3d_Vec2i	NbOffsetTilesMax () const
	Maximum number of tiles within offsets texture.

Graphic3d_Vec2i	OffsetTilesViewport (bool theAdaptive) const
	Viewport for rendering using offsets texture.

Graphic3d_Vec2i	OffsetTilesViewportMax () const
	Maximum viewport for rendering using offsets texture.

int	MaxTileSamples () const
	Return maximum number of samples per tile.

void	SetSize (const Graphic3d_RenderingParams &theParams, const Graphic3d_Vec2i &theSize)
	Specifies size of ray-tracing viewport and recomputes tile size.

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

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

bool	UploadSamples (const Handle< OpenGl_Context > &theContext, const Handle< OpenGl_Texture > &theSamplesTexture, const bool theAdaptive)
	Uploads tile samples to the given OpenGL texture.

bool	UploadOffsets (const Handle< OpenGl_Context > &theContext, const Handle< OpenGl_Texture > &theOffsetsTexture, const bool theAdaptive)
	Uploads offsets of sampled tiles to the given OpenGL texture.

Protected Member Functions
int	tileArea (int theX, int theY) const
	Returns number of pixels in the given tile.

Graphic3d_Vec2i	nextTileToSample ()
	Samples tile location according to estimated error.

bool	upload (const Handle< OpenGl_Context > &theContext, const Handle< OpenGl_Texture > &theSamplesTexture, const Handle< OpenGl_Texture > &theOffsetsTexture, const bool theAdaptive)
	Uploads offsets of sampled tiles to the given OpenGL texture.

void	dumpMap (std::ostream &theStream, const Image_PixMapTypedData< int > &theMap, const char *theTitle) const
	Auxiliary method for dumping 2D image map into stream (e.g. for debugging).

Protected Attributes
Image_PixMapTypedData< unsigned int >	myTiles
	number of samples per tile (initially all 1)

Image_PixMapTypedData< unsigned int >	myTileSamples
	number of samples for all pixels within the tile (initially equals to Tile area)

Image_PixMapTypedData< float >	myVarianceMap
	Estimation of visual error per tile.

Image_PixMapTypedData< int >	myVarianceRaw
	Estimation of visual error per tile (raw data)

Image_PixMapTypedData< Graphic3d_Vec2i >	myOffsets
	2D array of tiles redirecting to another tile

Image_PixMapTypedData< Graphic3d_Vec2i >	myOffsetsShrunk
	2D array of tiles redirecting to another tile (shrunk)

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

OpenGl_HaltonSampler	mySampler
	Halton sequence generator.

unsigned int	myLastSample
	Index of generated sample.

float	myScaleFactor
	scale factor for quantization of visual error (float) into signed integer

int	myTileSize
	tile size

Graphic3d_Vec2i	myViewSize
	ray-tracing viewport

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

◆ dumpMap()

void OpenGl_TileSampler::dumpMap	(	std::ostream &	theStream,
		const Image_PixMapTypedData< int > &	theMap,
		const char *	theTitle
	)		const

protected

Auxiliary method for dumping 2D image map into stream (e.g. for debugging).

◆ GrabVarianceMap()

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

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

◆ MaxTileSamples()

int OpenGl_TileSampler::MaxTileSamples ( ) const

inline

Return maximum number of samples per tile.

◆ NbOffsetTiles()

Graphic3d_Vec2i OpenGl_TileSampler::NbOffsetTiles ( bool theAdaptive ) const

inline

Number of tiles within offsets texture.

◆ NbOffsetTilesMax()

Graphic3d_Vec2i OpenGl_TileSampler::NbOffsetTilesMax ( ) const

inline

Maximum number of tiles within offsets texture.

◆ 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.

◆ nextTileToSample()

Graphic3d_Vec2i OpenGl_TileSampler::nextTileToSample ( )

protected

Samples tile location according to estimated error.

◆ OffsetTilesViewport()

Graphic3d_Vec2i OpenGl_TileSampler::OffsetTilesViewport ( bool theAdaptive ) const

inline

Viewport for rendering using offsets texture.

◆ OffsetTilesViewportMax()

Graphic3d_Vec2i OpenGl_TileSampler::OffsetTilesViewportMax ( ) const

inline

Maximum viewport for rendering using offsets texture.

◆ Reset()

void OpenGl_TileSampler::Reset ( )

inline

Resets (restart) tile sampler to initial state.

◆ SetSize()

void OpenGl_TileSampler::SetSize	(	const Graphic3d_RenderingParams &	theParams,
		const Graphic3d_Vec2i &	theSize
	)

Specifies size of ray-tracing viewport and recomputes tile size.

◆ tileArea()

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

inlineprotected

Returns number of pixels in the given tile.

◆ TileSize()

Graphic3d_Vec2i OpenGl_TileSampler::TileSize ( ) const

inline

Size of individual tile in pixels.

◆ upload()

bool OpenGl_TileSampler::upload	(	const Handle< OpenGl_Context > &	theContext,
		const Handle< OpenGl_Texture > &	theSamplesTexture,
		const Handle< OpenGl_Texture > &	theOffsetsTexture,
		const bool	theAdaptive
	)

protected

Uploads offsets of sampled tiles to the given OpenGL texture.

◆ UploadOffsets()

bool OpenGl_TileSampler::UploadOffsets	(	const Handle< OpenGl_Context > &	theContext,
		const Handle< OpenGl_Texture > &	theOffsetsTexture,
		const bool	theAdaptive
	)

inline

Uploads offsets of sampled tiles to the given OpenGL texture.

◆ UploadSamples()

bool OpenGl_TileSampler::UploadSamples	(	const Handle< OpenGl_Context > &	theContext,
		const Handle< OpenGl_Texture > &	theSamplesTexture,
		const bool	theAdaptive
	)

inline

Uploads tile samples to the given OpenGL texture.

◆ VarianceScaleFactor()

float OpenGl_TileSampler::VarianceScaleFactor ( ) const

inline

Scale factor for quantization of visual error (float) into signed integer.

◆ ViewSize()

const Graphic3d_Vec2i & OpenGl_TileSampler::ViewSize ( ) const

inline

Returns ray-tracing viewport.

Field Documentation

◆ myLastSample

unsigned int OpenGl_TileSampler::myLastSample

protected

Index of generated sample.

◆ myMarginalMap

std::vector<float> OpenGl_TileSampler::myMarginalMap

protected

Marginal distribution of 2D error map.

◆ myOffsets

Image_PixMapTypedData<Graphic3d_Vec2i> OpenGl_TileSampler::myOffsets

protected

2D array of tiles redirecting to another tile

◆ myOffsetsShrunk

Image_PixMapTypedData<Graphic3d_Vec2i> OpenGl_TileSampler::myOffsetsShrunk

protected

2D array of tiles redirecting to another tile (shrunk)

◆ mySampler

OpenGl_HaltonSampler OpenGl_TileSampler::mySampler

protected

Halton sequence generator.

◆ myScaleFactor

float OpenGl_TileSampler::myScaleFactor

protected

scale factor for quantization of visual error (float) into signed integer

◆ myTiles

Image_PixMapTypedData<unsigned int> OpenGl_TileSampler::myTiles

protected

number of samples per tile (initially all 1)

◆ myTileSamples

Image_PixMapTypedData<unsigned int> OpenGl_TileSampler::myTileSamples

protected

number of samples for all pixels within the tile (initially equals to Tile area)

◆ myTileSize

int OpenGl_TileSampler::myTileSize

protected

tile size

◆ myVarianceMap

Image_PixMapTypedData<float> OpenGl_TileSampler::myVarianceMap

protected

Estimation of visual error per tile.

◆ myVarianceRaw

Image_PixMapTypedData<int> OpenGl_TileSampler::myVarianceRaw

protected

Estimation of visual error per tile (raw data)

◆ myViewSize

Graphic3d_Vec2i OpenGl_TileSampler::myViewSize

protected

ray-tracing viewport

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

OpenGl_TileSampler.hxx

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ OpenGl_TileSampler()

Member Function Documentation

◆ dumpMap()

◆ GrabVarianceMap()

◆ MaxTileSamples()

◆ NbOffsetTiles()

◆ NbOffsetTilesMax()

◆ NbTiles()

◆ NbTilesX()

◆ NbTilesY()

◆ nextTileToSample()

◆ OffsetTilesViewport()

◆ OffsetTilesViewportMax()

◆ Reset()

◆ SetSize()

◆ tileArea()

◆ TileSize()

◆ upload()

◆ UploadOffsets()

◆ UploadSamples()

◆ VarianceScaleFactor()

◆ ViewSize()

Field Documentation

◆ myLastSample

◆ myMarginalMap

◆ myOffsets

◆ myOffsetsShrunk

◆ mySampler

◆ myScaleFactor

◆ myTiles

◆ myTileSamples

◆ myTileSize

◆ myVarianceMap

◆ myVarianceRaw

◆ myViewSize