OpenVDB 12.1.0
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GradStencil< GridT, IsSafe > Class Template Reference

#include <openvdb/math/Stencils.h>

Inheritance diagram for GradStencil< GridT, IsSafe >:
BaseStencil< GradStencil< GridT, true >, GridT, true >

Public Types

typedef GridT GridType
typedef GridT::TreeType TreeType
typedef GridType::ValueType ValueType
typedef tree::ValueAccessor< const TreeType, IsSafe > AccessorType
typedef std::vector< ValueTypeBufferType

Public Member Functions

 GradStencil (const GridType &grid)
 GradStencil (const GridType &grid, Real dx)
ValueType normSqGrad () const
 Return the norm square of the single-sided upwind gradient (computed via Godunov's scheme) at the previously buffered location.
math::Vec3< ValueTypegradient () const
 Return the gradient computed at the previously buffered location by second order central differencing.
math::Vec3< ValueTypegradient (const math::Vec3< ValueType > &V) const
 Return the first-order upwind gradient corresponding to the direction V.
ValueType laplacian () const
bool zeroCrossing () const
math::Vec3< ValueTypecpt ()
 Compute the closest-point transform to a level set.
template<int i, int j, int k>
unsigned int pos () const
 Return linear offset for the specified stencil point relative to its center.
void moveTo (const Coord &ijk)
 Initialize the stencil buffer with the values of voxel (i, j, k) and its neighbors.
const ValueTypegetValue (unsigned int pos=0) const
 Return the value from the stencil buffer with linear offset pos.
void setValue (const ValueType &value)
 Set the value at the specified location relative to the center of the stencil.
int size ()
 Return the size of the stencil buffer.
ValueType median () const
 Return the median value of the current stencil.
ValueType mean () const
 Return the mean value of the current stencil.
ValueType min () const
 Return the smallest value in the stencil buffer.
ValueType max () const
 Return the largest value in the stencil buffer.
const CoordgetCenterCoord () const
 Return the coordinates of the center point of the stencil.
const ValueTypegetCenterValue () const
 Return the value at the center of the stencil.
bool intersects (const ValueType &isoValue=zeroVal< ValueType >()) const
 Return true if the center of the stencil intersects the iso-contour specified by the isoValue.
std::bitset< 6 > intersectionMask (const ValueType &isoValue=zeroVal< ValueType >()) const
 Return true a bit-mask where the 6 bits indicates if the center of the stencil intersects the iso-contour specified by the isoValue.
const GridTypegrid () const
 Return a const reference to the grid from which this stencil was constructed.
const AccessorTypeaccessor () const
 Return a const reference to the ValueAccessor associated with this Stencil.

Static Public Attributes

static const int SIZE = 7

Protected Attributes

const GridTypemGrid
Coord mCenter

Friends

template<typename, typename, bool>
class BaseStencil

Detailed Description

template<typename GridT, bool IsSafe = true>
class openvdb::v12_1::math::GradStencil< GridT, IsSafe >

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

◆ AccessorType

typedef tree::ValueAccessor<const TreeType, IsSafe> AccessorType
inherited

◆ BufferType

typedef std::vector<ValueType> BufferType
inherited

◆ GridType

template<typename GridT, bool IsSafe = true>
typedef GridT GridType

◆ TreeType

template<typename GridT, bool IsSafe = true>
typedef GridT::TreeType TreeType

◆ ValueType

template<typename GridT, bool IsSafe = true>
typedef GridType::ValueType ValueType

Constructor & Destructor Documentation

◆ GradStencil() [1/2]

template<typename GridT, bool IsSafe = true>
GradStencil ( const GridType & grid)
inline

◆ GradStencil() [2/2]

template<typename GridT, bool IsSafe = true>
GradStencil ( const GridType & grid,
Real dx )
inline

Member Function Documentation

◆ accessor()

const AccessorType & accessor ( ) const
inlineinherited

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

◆ cpt()

template<typename GridT, bool IsSafe = true>
math::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.

◆ getCenterCoord()

const Coord & getCenterCoord ( ) const
inlineinherited

Return the coordinates of the center point of the stencil.

◆ getCenterValue()

const ValueType & getCenterValue ( ) const
inlineinherited

Return the value at the center of the stencil.

◆ getValue()

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.

◆ gradient() [1/2]

template<typename GridT, bool IsSafe = true>
math::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).

◆ gradient() [2/2]

template<typename GridT, bool IsSafe = true>
math::Vec3< ValueType > gradient ( const math::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).

◆ grid()

const GridType & grid ( ) const
inlineinherited

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

◆ intersectionMask()

std::bitset< 6 > intersectionMask ( const ValueType & isoValue = zeroVal<ValueType>()) const
inlineinherited

Return true a bit-mask where the 6 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.test(2) where mask is ther return value from this function. To check if there are any intersections use mask.any(), and for no intersections use mask.none(). To count the number of intersections use mask.count().

◆ intersects()

bool intersects ( const ValueType & isoValue = zeroVal<ValueType>()) const
inlineinherited

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

◆ laplacian()

template<typename GridT, bool IsSafe = true>
ValueType laplacian ( ) const
inline

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

◆ max()

ValueType max ( ) const
inlineinherited

Return the largest value in the stencil buffer.

◆ mean()

ValueType mean ( ) const
inlineinherited

Return the mean value of the current stencil.

◆ median()

ValueType median ( ) const
inlineinherited

Return the median value of the current stencil.

◆ min()

ValueType min ( ) const
inlineinherited

Return the smallest value in the stencil buffer.

◆ moveTo()

void moveTo ( const Coord & ijk)
inlineinherited

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

Parameters
ijkIndex coordinates of stencil center

◆ normSqGrad()

template<typename GridT, bool IsSafe = true>
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).

◆ pos()

template<typename GridT, bool IsSafe = true>
template<int i, int j, int k>
unsigned int pos ( ) const
inline

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

◆ setValue()

void setValue ( const ValueType & value)
inlineinherited

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

◆ size()

int size ( )
inlineinherited

Return the size of the stencil buffer.

◆ zeroCrossing()

template<typename GridT, bool IsSafe = true>
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.

◆ BaseStencil

template<typename GridT, bool IsSafe = true>
template<typename, typename, bool>
friend class BaseStencil
friend

Member Data Documentation

◆ mCenter

Coord mCenter
protectedinherited

◆ mGrid

const GridType* mGrid
protectedinherited

◆ SIZE

template<typename GridT, bool IsSafe = true>
const int SIZE = 7
static