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/*=========================================================================
Program: Visualization Toolkit
Module: vtkAbstractInterpolatedVelocityField.h
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
/**
* @class vtkAbstractInterpolatedVelocityField
* @brief An abstract class for
* obtaining the interpolated velocity values at a point
*
*
* vtkAbstractInterpolatedVelocityField acts as a continuous velocity field
* by performing cell interpolation on the underlying vtkDataSet. This is an
* abstract sub-class of vtkFunctionSet, NumberOfIndependentVariables = 4
* (x,y,z,t) and NumberOfFunctions = 3 (u,v,w). With a brute-force scheme,
* every time an evaluation is performed, the target cell containing point
* (x,y,z) needs to be found by calling FindCell(), via either vtkDataSet or
* vtkAbstractCelllocator's sub-classes (vtkCellLocator & vtkModifiedBSPTree).
* As it incurs a large cost, one (for vtkCellLocatorInterpolatedVelocityField
* via vtkAbstractCellLocator) or two (for vtkInterpolatedVelocityField via
* vtkDataSet that involves vtkPointLocator in addressing vtkPointSet) levels
* of cell caching may be exploited to increase the performance.
*
* For vtkInterpolatedVelocityField, level #0 begins with intra-cell caching.
* Specifically if the previous cell is valid and the next point is still in
* it ( i.e., vtkCell::EvaluatePosition() returns 1, coupled with newly created
* parametric coordinates & weights ), the function values can be interpolated
* and only vtkCell::EvaluatePosition() is invoked. If this fails, then level #1
* follows by inter-cell search for the target cell that contains the next point.
* By an inter-cell search, the previous cell provides an important clue or serves
* as an immediate neighbor to aid in locating the target cell via vtkPointSet::
* FindCell(). If this still fails, a global cell location / search is invoked via
* vtkPointSet::FindCell(). Here regardless of either inter-cell or global search,
* vtkPointLocator is in fact employed (for datasets of type vtkPointSet only, note
* vtkImageData and vtkRectilinearGrid are able to provide rapid and robust cell
* location due to the simple mesh topology) as a crucial tool underlying the cell
* locator. However, the use of vtkPointLocator makes vtkInterpolatedVelocityField
* non-robust in cell location for vtkPointSet.
*
* For vtkCellLocatorInterpolatedVelocityField, the only caching (level #0) works
* by intra-cell trial. In case of failure, a global search for the target cell is
* invoked via vtkAbstractCellLocator::FindCell() and the actual work is done by
* either vtkCellLocator or vtkModifiedBSPTree (for datasets of type vtkPointSet
* only, while vtkImageData and vtkRectilinearGrid themselves are able to provide
* fast robust cell location). Without the involvement of vtkPointLocator, robust
* cell location is achieved for vtkPointSet.
*
* @warning
* vtkAbstractInterpolatedVelocityField is not thread safe. A new instance
* should be created by each thread.
*
* @sa
* vtkInterpolatedVelocityField vtkCellLocatorInterpolatedVelocityField
* vtkGenericInterpolatedVelocityField vtkCachingInterpolatedVelocityField
* vtkTemporalInterpolatedVelocityField vtkFunctionSet vtkStreamTracer
*/
#ifndef vtkAbstractInterpolatedVelocityField_h
#define vtkAbstractInterpolatedVelocityField_h
#include "vtkFunctionSet.h"
class vtkDataSet;
class vtkDataArray;
class vtkPointData;
class vtkGenericCell;
class vtkAbstractInterpolatedVelocityFieldDataSetsType;
class vtkFindCellStrategy;
struct vtkStrategyMap;
#include "vtkFiltersFlowPathsModule.h" // For export macro
class VTKFILTERSFLOWPATHS_EXPORT vtkAbstractInterpolatedVelocityField : public vtkFunctionSet
{
public:
vtkTypeMacro(vtkAbstractInterpolatedVelocityField, vtkFunctionSet);
void PrintSelf(ostream& os, vtkIndent indent) override;
//@{
/**
* Set/Get the caching flag. If this flag is turned ON, there are two levels
* of caching for derived concrete class vtkInterpolatedVelocityField and one
* level of caching for derived concrete class vtkCellLocatorInterpolatedVelocityField.
* Otherwise a global cell location is always invoked for evaluating the
* function values at any point.
*/
vtkSetMacro(Caching, bool);
vtkGetMacro(Caching, bool);
//@}
//@{
/**
* Get the caching statistics. CacheHit refers to the number of level #0 cache
* hits while CacheMiss is the number of level #0 cache misses.
*/
vtkGetMacro(CacheHit, int);
vtkGetMacro(CacheMiss, int);
//@}
vtkGetObjectMacro(LastDataSet, vtkDataSet);
//@{
/**
* Get/Set the id of the cell cached from last evaluation.
*/
vtkGetMacro(LastCellId, vtkIdType);
virtual void SetLastCellId(vtkIdType c) { this->LastCellId = c; }
//@}
/**
* Set the id of the most recently visited cell of a dataset.
*/
virtual void SetLastCellId(vtkIdType c, int dataindex) = 0;
//@{
/**
* Get/Set the name of a spcified vector array. By default it is nullptr, with
* the active vector array for use.
*/
vtkGetStringMacro(VectorsSelection);
vtkGetMacro(VectorsType, int);
//@}
/**
* the association type (see vtkDataObject::FieldAssociations)
* and the name of the velocity data field
*/
void SelectVectors(int fieldAssociation, const char* fieldName);
//@{
/**
* Set/Get the flag indicating vector post-normalization (following vector
* interpolation). Vector post-normalization is required to avoid the
* 'curve-overshooting' problem (caused by high velocity magnitude) that
* occurs when Cell-Length is used as the step size unit (particularly the
* Minimum step size unit). Furthermore, it is required by RK45 to achieve,
* as expected, high numerical accuracy (or high smoothness of flow lines)
* through adaptive step sizing. Note this operation is performed (when
* NormalizeVector TRUE) right after vector interpolation such that the
* differing amount of contribution of each node (of a cell) to the
* resulting direction of the interpolated vector, due to the possibly
* significantly-differing velocity magnitude values at the nodes (which is
* the case with large cells), can be reflected as is. Also note that this
* flag needs to be turned to FALSE after vtkInitialValueProblemSolver::
* ComputeNextStep() as subsequent operations, e.g., vorticity computation,
* may need non-normalized vectors.
*/
vtkSetMacro(NormalizeVector, bool);
vtkGetMacro(NormalizeVector, bool);
//@}
//@{
/**
* If set to true, the first three point of the cell will be used to compute a normal to the cell,
* this normal will then be removed from the vorticity so the resulting vector in tangent to the
* cell.
*/
vtkSetMacro(ForceSurfaceTangentVector, bool);
vtkGetMacro(ForceSurfaceTangentVector, bool);
//@}
//@{
/**
* If set to true, cell within tolerance factor will always be found, except for edges.
*/
vtkSetMacro(SurfaceDataset, bool);
vtkGetMacro(SurfaceDataset, bool);
//@}
/**
* Import parameters. Sub-classes can add more after chaining.
*/
virtual void CopyParameters(vtkAbstractInterpolatedVelocityField* from);
using Superclass::FunctionValues;
/**
* Evaluate the velocity field f at point (x, y, z).
*/
int FunctionValues(double* x, double* f) override = 0;
/**
* Set the last cell id to -1 to incur a global cell search for the next point.
*/
void ClearLastCellId() { this->LastCellId = -1; }
//@{
/**
* Get the interpolation weights cached from last evaluation. Return 1 if the
* cached cell is valid and 0 otherwise.
*/
int GetLastWeights(double* w);
int GetLastLocalCoordinates(double pcoords[3]);
//@}
//@{
/**
* Set / get the strategy used to perform the FindCell() operation. This
* strategy is used when operating on vtkPointSet subclasses. Note if the
* input is a composite dataset then the strategy will be used to clone
* one strategy per leaf dataset.
*/
virtual void SetFindCellStrategy(vtkFindCellStrategy*);
vtkGetObjectMacro(FindCellStrategy, vtkFindCellStrategy);
//@}
protected:
vtkAbstractInterpolatedVelocityField();
~vtkAbstractInterpolatedVelocityField() override;
static const double TOLERANCE_SCALE;
static const double SURFACE_TOLERANCE_SCALE;
int CacheHit;
int CacheMiss;
int WeightsSize;
bool Caching;
bool NormalizeVector;
bool ForceSurfaceTangentVector;
bool SurfaceDataset;
int VectorsType;
char* VectorsSelection;
double* Weights;
double LastPCoords[3];
int LastSubId;
vtkIdType LastCellId;
vtkDataSet* LastDataSet;
vtkGenericCell* Cell;
vtkGenericCell* GenCell; // the current cell
// Define a FindCell() strategy, keep track of the strategies assigned to
// each dataset
vtkFindCellStrategy* FindCellStrategy;
vtkStrategyMap* StrategyMap;
//@{
/**
* Set the name of a specific vector to be interpolated.
*/
vtkSetStringMacro(VectorsSelection);
//@}
/**
* Evaluate the velocity field f at point (x, y, z) in a specified dataset
* by invoking vtkDataSet::FindCell() to locate the next cell if the given
* point is outside the current cell. To address vtkPointSet, vtkPointLocator
* is involved via vtkPointSet::FindCell() in vtkInterpolatedVelocityField
* for cell location. In vtkCellLocatorInterpolatedVelocityField, this function
* is invoked just to handle vtkImageData and vtkRectilinearGrid that are not
* assigned with any vtkAbstractCellLocatot-type cell locator.
* If activated, returned vector will be tangential to the first
* three point of the cell
*/
virtual int FunctionValues(vtkDataSet* ds, double* x, double* f);
/**
* Check that all three pcoords are between 0 and 1 included.
*/
virtual bool CheckPCoords(double pcoords[3]);
/**
* Try to find the cell closest to provided x point in provided dataset,
* By first testing inclusion in it's cached cell and neighbor
* Then testing globally
* Then , only if surfacic is activated finding the closest cell
* using FindPoint and comparing distance with tolerance
*/
virtual bool FindAndUpdateCell(vtkDataSet* ds, double* x);
friend class vtkTemporalInterpolatedVelocityField;
//@{
/**
* If all weights have been computed (parametric coords etc all valid), a
* scalar/vector can be quickly interpolated using the known weights and
* the cached generic cell. This function is primarily reserved for use by
* vtkTemporalInterpolatedVelocityField
*/
void FastCompute(vtkDataArray* vectors, double f[3]);
bool InterpolatePoint(vtkPointData* outPD, vtkIdType outIndex);
vtkGenericCell* GetLastCell() { return (this->LastCellId != -1) ? this->GenCell : nullptr; }
//@}
private:
vtkAbstractInterpolatedVelocityField(const vtkAbstractInterpolatedVelocityField&) = delete;
void operator=(const vtkAbstractInterpolatedVelocityField&) = delete;
};
#endif