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vtkGenericCellTessellator Class Referenceabstract

helper class to perform cell tessellation More...

#include <vtkGenericCellTessellator.h>

Inheritance diagram for vtkGenericCellTessellator:
[legend]

Public Types

typedef vtkObject Superclass
 

Public Member Functions

virtual int IsA (const char *type)
 
vtkGenericCellTessellatorNewInstance () const
 
void PrintSelf (ostream &os, vtkIndent indent)
 
virtual void Initialize (vtkGenericDataSet *ds)=0
 
void InitErrorMetrics (vtkGenericDataSet *ds)
 
void GetMaxErrors (double *errors)
 
virtual void TessellateFace (vtkGenericAdaptorCell *cell, vtkGenericAttributeCollection *att, vtkIdType index, vtkDoubleArray *points, vtkCellArray *cellArray, vtkPointData *internalPd)=0
 
virtual void Tessellate (vtkGenericAdaptorCell *cell, vtkGenericAttributeCollection *att, vtkDoubleArray *points, vtkCellArray *cellArray, vtkPointData *internalPd)=0
 
virtual void Triangulate (vtkGenericAdaptorCell *cell, vtkGenericAttributeCollection *att, vtkDoubleArray *points, vtkCellArray *cellArray, vtkPointData *internalPd)=0
 
virtual void SetErrorMetrics (vtkCollection *someErrorMetrics)
 
virtual vtkCollection * GetErrorMetrics ()
 
virtual int GetMeasurement ()
 
virtual void SetMeasurement (int)
 

Static Public Member Functions

static int IsTypeOf (const char *type)
 
static vtkGenericCellTessellatorSafeDownCast (vtkObjectBase *o)
 

Protected Member Functions

virtual vtkObjectBase * NewInstanceInternal () const
 
 vtkGenericCellTessellator ()
 
 ~vtkGenericCellTessellator ()
 
void ResetMaxErrors ()
 
void SetGenericCell (vtkGenericAdaptorCell *cell)
 
int RequiresEdgeSubdivision (double *left, double *mid, double *right, double alpha)
 
virtual void UpdateMaxError (double *leftPoint, double *midPoint, double *rightPoint, double alpha)
 

Protected Attributes

vtkCollection * ErrorMetrics
 
vtkGenericDataSet * DataSet
 
int Measurement
 
double * MaxErrors
 
int MaxErrorsCapacity
 

Detailed Description

helper class to perform cell tessellation

vtkGenericCellTessellator is a helper class to perform adaptive tessellation of particular cell topologies. The major purpose for this class is to transform higher-order cell types (e.g., higher-order finite elements) into linear cells that can then be easily visualized by VTK. This class works in conjunction with the vtkGenericDataSet and vtkGenericAdaptorCell classes.

This algorithm is based on edge subdivision. An error metric along each edge is evaluated, and if the error is greater than some tolerance, the edge is subdivided (as well as all connected 2D and 3D cells). The process repeats until the error metric is satisfied.

A significant issue addressed by this algorithm is to insure face compatibility across neigboring cells. That is, diagonals due to face triangulation must match to insure that the mesh is compatible. The algorithm employs a precomputed table to accelerate the tessellation process. The table was generated with the help of vtkOrderedTriangulator; the basic idea is that the choice of diagonal is made by considering the relative value of the point ids.

Definition at line 57 of file vtkGenericCellTessellator.h.

Member Typedef Documentation

Definition at line 60 of file vtkGenericCellTessellator.h.

Constructor & Destructor Documentation

vtkGenericCellTessellator::vtkGenericCellTessellator ( )
protected
vtkGenericCellTessellator::~vtkGenericCellTessellator ( )
protected

Member Function Documentation

static int vtkGenericCellTessellator::IsTypeOf ( const char *  type)
static
virtual int vtkGenericCellTessellator::IsA ( const char *  type)
virtual

Reimplemented in vtkSimpleCellTessellator.

static vtkGenericCellTessellator* vtkGenericCellTessellator::SafeDownCast ( vtkObjectBase *  o)
static
virtual vtkObjectBase* vtkGenericCellTessellator::NewInstanceInternal ( ) const
protectedvirtual

Reimplemented in vtkSimpleCellTessellator.

vtkGenericCellTessellator* vtkGenericCellTessellator::NewInstance ( ) const
void vtkGenericCellTessellator::PrintSelf ( ostream &  os,
vtkIndent  indent 
)
virtual void vtkGenericCellTessellator::TessellateFace ( vtkGenericAdaptorCell cell,
vtkGenericAttributeCollection *  att,
vtkIdType  index,
vtkDoubleArray *  points,
vtkCellArray cellArray,
vtkPointData *  internalPd 
)
pure virtual

Tessellate a face of a 3D `cell'. The face is specified by the index value. The result is a set of smaller linear triangles in `cellArray' with `points' and point data `internalPd'.

Precondition
cell_exists: cell!=0
valid_dimension: cell->GetDimension()==3
valid_index_range: (index>=0) && (index<cell->GetNumberOfBoundaries(2))
att_exists: att!=0
points_exists: points!=0
cellArray_exists: cellArray!=0
internalPd_exists: internalPd!=0

Implemented in vtkSimpleCellTessellator.

virtual void vtkGenericCellTessellator::Tessellate ( vtkGenericAdaptorCell cell,
vtkGenericAttributeCollection *  att,
vtkDoubleArray *  points,
vtkCellArray cellArray,
vtkPointData *  internalPd 
)
pure virtual

Tessellate a 3D `cell'. The result is a set of smaller linear tetrahedra in `cellArray' with `points' and point data `internalPd'.

Precondition
cell_exists: cell!=0
valid_dimension: cell->GetDimension()==3
att_exists: att!=0
points_exists: points!=0
cellArray_exists: cellArray!=0
internalPd_exists: internalPd!=0

Implemented in vtkSimpleCellTessellator.

virtual void vtkGenericCellTessellator::Triangulate ( vtkGenericAdaptorCell cell,
vtkGenericAttributeCollection *  att,
vtkDoubleArray *  points,
vtkCellArray cellArray,
vtkPointData *  internalPd 
)
pure virtual

Triangulate a 2D `cell'. The result is a set of smaller linear triangles in `cellArray' with `points' and point data `internalPd'.

Precondition
cell_exists: cell!=0
valid_dimension: cell->GetDimension()==2
att_exists: att!=0
points_exists: points!=0
cellArray_exists: cellArray!=0
internalPd_exists: internalPd!=0

Implemented in vtkSimpleCellTessellator.

virtual void vtkGenericCellTessellator::SetErrorMetrics ( vtkCollection *  someErrorMetrics)
virtual

Specify the list of error metrics used to decide if an edge has to be splitted or not. It is a collection of vtkGenericSubdivisionErrorMetric-s.

virtual vtkCollection* vtkGenericCellTessellator::GetErrorMetrics ( )
virtual

Specify the list of error metrics used to decide if an edge has to be splitted or not. It is a collection of vtkGenericSubdivisionErrorMetric-s.

virtual void vtkGenericCellTessellator::Initialize ( vtkGenericDataSet *  ds)
pure virtual

Initialize the tessellator with a data set `ds'.

Implemented in vtkSimpleCellTessellator.

void vtkGenericCellTessellator::InitErrorMetrics ( vtkGenericDataSet *  ds)

Init the error metric with the dataset. Should be called in each filter before any tessellation of any cell.

virtual int vtkGenericCellTessellator::GetMeasurement ( )
virtual

If true, measure the quality of the fixed subdivision.

virtual void vtkGenericCellTessellator::SetMeasurement ( int  )
virtual

If true, measure the quality of the fixed subdivision.

void vtkGenericCellTessellator::GetMaxErrors ( double *  errors)

Get the maximum error measured after the fixed subdivision.

Precondition
errors_exists: errors!=0
valid_size: sizeof(errors)==GetErrorMetrics()->GetNumberOfItems()
int vtkGenericCellTessellator::RequiresEdgeSubdivision ( double *  left,
double *  mid,
double *  right,
double  alpha 
)
protected

Does the edge need to be subdivided according to at least one error metric? The edge is defined by its `leftPoint' and its `rightPoint'. `leftPoint', `midPoint' and `rightPoint' have to be initialized before calling RequiresEdgeSubdivision(). Their format is global coordinates, parametric coordinates and point centered attributes: xyx rst abc de... `alpha' is the normalized abscissa of the midpoint along the edge. (close to 0 means close to the left point, close to 1 means close to the right point)

Precondition
leftPoint_exists: leftPoint!=0
midPoint_exists: midPoint!=0
rightPoint_exists: rightPoint!=0
clamped_alpha: alpha>0 && alpha<1
valid_size: sizeof(leftPoint)=sizeof(midPoint)=sizeof(rightPoint) =GetAttributeCollection()->GetNumberOfPointCenteredComponents()+6
virtual void vtkGenericCellTessellator::UpdateMaxError ( double *  leftPoint,
double *  midPoint,
double *  rightPoint,
double  alpha 
)
protectedvirtual

Update the max error of each error metric according to the error at the mid-point. The type of error depends on the state of the concrete error metric. For instance, it can return an absolute or relative error metric. See RequiresEdgeSubdivision() for a description of the arguments.

Precondition
leftPoint_exists: leftPoint!=0
midPoint_exists: midPoint!=0
rightPoint_exists: rightPoint!=0
clamped_alpha: alpha>0 && alpha<1
valid_size: sizeof(leftPoint)=sizeof(midPoint)=sizeof(rightPoint) =GetAttributeCollection()->GetNumberOfPointCenteredComponents()+6
void vtkGenericCellTessellator::ResetMaxErrors ( )
protected

Reset the maximal error of each error metric. The purpose of the maximal error is to measure the quality of a fixed subdivision.

void vtkGenericCellTessellator::SetGenericCell ( vtkGenericAdaptorCell cell)
protected

Send the current cell to error metrics. Should be called at the beginning of the implementation of Tessellate(), Triangulate() or TessellateFace()

Precondition
cell_exists: cell!=0

Member Data Documentation

vtkCollection* vtkGenericCellTessellator::ErrorMetrics
protected

List of error metrics. Collection of vtkGenericSubdivisionErrorMetric

Definition at line 174 of file vtkGenericCellTessellator.h.

vtkGenericDataSet* vtkGenericCellTessellator::DataSet
protected

Definition at line 181 of file vtkGenericCellTessellator.h.

int vtkGenericCellTessellator::Measurement
protected

Definition at line 183 of file vtkGenericCellTessellator.h.

double* vtkGenericCellTessellator::MaxErrors
protected

Definition at line 184 of file vtkGenericCellTessellator.h.

int vtkGenericCellTessellator::MaxErrorsCapacity
protected

Definition at line 186 of file vtkGenericCellTessellator.h.


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