#include <nanovdb/util/Stencils.h>

Inherits BaseStencil< GradStencil< GridT >, 7, GridT >.

Public Types
using	GridType = GridT

using	TreeType = typename GridT::TreeType

using	ValueType = typename GridT::ValueType

using	AccessorType = ReadAccessor< ValueType >

Public Member Functions
	GradStencil (const GridType &grid)

	GradStencil (const GridType &grid, double dx)

ValueType	normSqGrad () const
	Return the norm square of the single-sided upwind gradient (computed via Godunov's scheme) at the previously buffered location. More...

Vec3< ValueType >	gradient () const
	Return the gradient computed at the previously buffered location by second order central differencing. More...

Vec3< ValueType >	gradient (const Vec3< ValueType > &V) const
	Return the first-order upwind gradient corresponding to the direction V. More...

ValueType	laplacian () const

bool	zeroCrossing () const

Vec3< ValueType >	cpt ()
	Compute the closest-point transform to a level set. More...

template<int i, int j, int k>
unsigned int	pos () const
	Return linear offset for the specified stencil point relative to its center. More...

void	moveTo (const Coord &ijk)
	Initialize the stencil buffer with the values of voxel (i, j, k) and its neighbors. More...

void	moveTo (const Coord &ijk, const ValueType &centerValue)
	Initialize the stencil buffer with the values of voxel (i, j, k) and its neighbors. The method also takes a value of the center element of the stencil, assuming it is already known. More...

void	moveTo (const IterType &iter)
	Initialize the stencil buffer with the values of voxel (x, y, z) and its neighbors. More...

void	moveTo (const Vec3< RealType > &xyz)
	Initialize the stencil buffer with the values of voxel (x, y, z) and its neighbors. More...

const ValueType &	getValue (unsigned int pos=0) const
	Return the value from the stencil buffer with linear offset pos. More...

const ValueType &	getValue () const
	Return the value at the specified location relative to the center of the stencil. More...

void	setValue (const ValueType &value)
	Set the value at the specified location relative to the center of the stencil. More...

ValueType	mean () const
	Return the mean value of the current stencil. More...

ValueType	min () const
	Return the smallest value in the stencil buffer. More...

ValueType	max () const
	Return the largest value in the stencil buffer. More...

const Coord &	getCenterCoord () const
	Return the coordinates of the center point of the stencil. More...

const ValueType &	getCenterValue () const
	Return the value at the center of the stencil. More...

bool	intersects (const ValueType &isoValue=ValueType(0)) const
	Return true if the center of the stencil intersects the iso-contour specified by the isoValue. More...

Mask	intersectionMask (ValueType isoValue=ValueType(0)) const
	Return true a bit-mask where the 6 lower bits indicates if the center of the stencil intersects the iso-contour specified by the isoValue. More...

const GridType &	grid () const
	Return a const reference to the grid from which this stencil was constructed. More...

const AccessorType &	accessor () const
	Return a const reference to the ValueAccessor associated with this Stencil. More...

Static Public Member Functions
static int	size ()
	Return the size of the stencil buffer. More...

Static Public Attributes
static constexpr int	SIZE = 7

Protected Attributes
const GridType *	mGrid

AccessorType	mAcc

ValueType	mValues [SIZE]

Coord	mCenter

Friends
template<typename , int , typename >
class	BaseStencil

Detailed Description

template<typename GridT>
class nanovdb::GradStencil< GridT >

This is a simple 7-point nearest neighbor stencil that supports gradient by second-order central differencing, first-order upwinding, Laplacian, closest-point transform and zero-crossing test.

Note: For optimal random access performance this class includes its own grid accessor.

Member Typedef Documentation

using AccessorType = ReadAccessor<ValueType>

inherited

using GridType = GridT

using TreeType = typename GridT::TreeType

using ValueType = typename GridT::ValueType

Constructor & Destructor Documentation

GradStencil ( const GridType & grid )

inline

GradStencil	(	const GridType &	grid,
		double	dx
	)

inline

Member Function Documentation

const AccessorType& accessor ( ) const

inlineinherited

Return a const reference to the ValueAccessor associated with this Stencil.

Vec3<ValueType> cpt ( )

inline

Compute the closest-point transform to a level set.

Returns: the closest point in index space to the surface from which the level set was derived.

Note: This method assumes that the grid represents a level set with distances in world units and a simple affine transfrom with uniform scaling.

const Coord& getCenterCoord ( ) const

inlineinherited

Return the coordinates of the center point of the stencil.

const ValueType& getCenterValue ( ) const

inlineinherited

Return the value at the center of the stencil.

const ValueType& getValue ( unsigned int pos = 0 ) const

inlineinherited

Return the value from the stencil buffer with linear offset pos.

Note: The default (pos = 0) corresponds to the first element which is typically the center point of the stencil.

const ValueType& getValue ( ) const

inlineinherited

Return the value at the specified location relative to the center of the stencil.

Vec3<ValueType> gradient ( ) const

inline

Return the gradient computed at the previously buffered location by second order central differencing.

Note: This method should not be called until the stencil buffer has been populated via a call to moveTo(ijk).

Vec3<ValueType> gradient ( const Vec3< ValueType > & V ) const

inline

Return the first-order upwind gradient corresponding to the direction V.

Note: This method should not be called until the stencil buffer has been populated via a call to moveTo(ijk).

const GridType& grid ( ) const

inlineinherited

Return a const reference to the grid from which this stencil was constructed.

Mask intersectionMask ( ValueType isoValue = ValueType(0) ) const

inlineinherited

Return true a bit-mask where the 6 lower bits indicates if the center of the stencil intersects the iso-contour specified by the isoValue.

Note: There are 2^6 = 64 different possible cases, including no intersections!

The ordering of bit mask is ( -x, +x, -y, +y, -z, +z ), so to check if there is an intersection in -y use (mask & (1u<<2)) where mask is ther return value from this function. To check if there are any intersections use mask!=0u, and for no intersections use mask==0u. To count the number of intersections use __builtin_popcount(mask).

bool intersects ( const ValueType & isoValue = ValueType(0) ) const

inlineinherited

Return true if the center of the stencil intersects the iso-contour specified by the isoValue.

ValueType laplacian ( ) const

inline

Return the Laplacian computed at the previously buffered location by second-order central differencing.

ValueType max ( ) const

inlineinherited

Return the largest value in the stencil buffer.

ValueType mean ( ) const

inlineinherited

Return the mean value of the current stencil.

ValueType min ( ) const

inlineinherited

Return the smallest value in the stencil buffer.

void moveTo ( const Coord & ijk )

inlineinherited

Initialize the stencil buffer with the values of voxel (i, j, k) and its neighbors.

Parameters

ijk	Index coordinates of stencil center

void moveTo	(	const Coord &	ijk,
		const ValueType &	centerValue
	)

inlineinherited

Initialize the stencil buffer with the values of voxel (i, j, k) and its neighbors. The method also takes a value of the center element of the stencil, assuming it is already known.

Parameters

ijk	Index coordinates of stencil center
centerValue	Value of the center element of the stencil

void moveTo ( const IterType & iter )

inlineinherited

Initialize the stencil buffer with the values of voxel (x, y, z) and its neighbors.

Note: This version is slightly faster than the one above, since the center voxel's value is read directly from the iterator.

void moveTo ( const Vec3< RealType > & xyz )

inlineinherited

Initialize the stencil buffer with the values of voxel (x, y, z) and its neighbors.

Parameters

xyz	Floating point voxel coordinates of stencil center

This method will check to see if it is necessary to update the stencil based on the cached index coordinates of the center point.

ValueType normSqGrad ( ) const

inline

Return the norm square of the single-sided upwind gradient (computed via Godunov's scheme) at the previously buffered location.

Note: This method should not be called until the stencil buffer has been populated via a call to moveTo(ijk).

unsigned int pos ( ) const

inline

Return linear offset for the specified stencil point relative to its center.

void setValue ( const ValueType & value )

inlineinherited

Set the value at the specified location relative to the center of the stencil.

static int size ( )

inlinestaticinherited

Return the size of the stencil buffer.

bool zeroCrossing ( ) const

inline

Return true if the sign of the value at the center point of the stencil is different from the signs of any of its six nearest neighbors.

Friends And Related Function Documentation

friend class BaseStencil

friend

Member Data Documentation

AccessorType mAcc

protectedinherited

Coord mCenter

protectedinherited

const GridType* mGrid

protectedinherited

ValueType mValues[SIZE]

protectedinherited

constexpr int SIZE = 7

static

Public Types

Public Member Functions

Static Public Member Functions

Static Public Attributes

Protected Attributes

Friends

Detailed Description

template<typename GridT> class nanovdb::GradStencil< GridT >

Member Typedef Documentation

Constructor & Destructor Documentation

Member Function Documentation

Friends And Related Function Documentation

Member Data Documentation

template<typename GridT>
class nanovdb::GradStencil< GridT >