Permalink
Switch branches/tags
Nothing to show
Find file
Fetching contributors…
Cannot retrieve contributors at this time
204 lines (175 sloc) 8.32 KB
/*=========================================================================
Program: Visualization Toolkit
Module: vtkGenericCellTessellator.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.
=========================================================================*/
// .NAME vtkGenericCellTessellator - helper class to perform cell tessellation
// .SECTION Description
// 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.
#ifndef __vtkGenericCellTessellator_h
#define __vtkGenericCellTessellator_h
#include "vtkObject.h"
class vtkCellArray;
class vtkDoubleArray;
class vtkCollection;
class vtkGenericAttributeCollection;
class vtkGenericAdaptorCell;
class vtkGenericCellIterator;
class vtkPointData;
class vtkGenericDataSet;
//-----------------------------------------------------------------------------
//
// The tessellation object
class VTK_FILTERING_EXPORT vtkGenericCellTessellator : public vtkObject
{
public:
vtkTypeMacro(vtkGenericCellTessellator,vtkObject);
void PrintSelf(ostream& os, vtkIndent indent);
// Description:
// 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'.
// \pre cell_exists: cell!=0
// \pre valid_dimension: cell->GetDimension()==3
// \pre valid_index_range: (index>=0) && (index<cell->GetNumberOfBoundaries(2))
// \pre att_exists: att!=0
// \pre points_exists: points!=0
// \pre cellArray_exists: cellArray!=0
// \pre internalPd_exists: internalPd!=0
virtual void TessellateFace(vtkGenericAdaptorCell *cell,
vtkGenericAttributeCollection *att,
vtkIdType index,
vtkDoubleArray *points,
vtkCellArray *cellArray,
vtkPointData *internalPd)=0;
// Description:
// Tessellate a 3D `cell'. The result is a set of smaller linear
// tetrahedra in `cellArray' with `points' and point data `internalPd'.
// \pre cell_exists: cell!=0
// \pre valid_dimension: cell->GetDimension()==3
// \pre att_exists: att!=0
// \pre points_exists: points!=0
// \pre cellArray_exists: cellArray!=0
// \pre internalPd_exists: internalPd!=0
virtual void Tessellate(vtkGenericAdaptorCell *cell,
vtkGenericAttributeCollection *att,
vtkDoubleArray *points,
vtkCellArray *cellArray,
vtkPointData *internalPd )=0;
// Description:
// Triangulate a 2D `cell'. The result is a set of smaller linear triangles
// in `cellArray' with `points' and point data `internalPd'.
// \pre cell_exists: cell!=0
// \pre valid_dimension: cell->GetDimension()==2
// \pre att_exists: att!=0
// \pre points_exists: points!=0
// \pre cellArray_exists: cellArray!=0
// \pre internalPd_exists: internalPd!=0
virtual void Triangulate(vtkGenericAdaptorCell *cell,
vtkGenericAttributeCollection *att,
vtkDoubleArray *points,
vtkCellArray *cellArray,
vtkPointData *internalPd)=0;
// Description:
// 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 SetErrorMetrics(vtkCollection *someErrorMetrics);
vtkGetObjectMacro(ErrorMetrics,vtkCollection);
// Description:
// Initialize the tessellator with a data set `ds'.
virtual void Initialize(vtkGenericDataSet *ds)=0;
// Description:
// Init the error metric with the dataset. Should be called in each filter
// before any tessellation of any cell.
void InitErrorMetrics(vtkGenericDataSet *ds);
// Description:
// If true, measure the quality of the fixed subdivision.
vtkGetMacro(Measurement,int);
vtkSetMacro(Measurement,int);
// Description:
// Get the maximum error measured after the fixed subdivision.
// \pre errors_exists: errors!=0
// \pre valid_size: sizeof(errors)==GetErrorMetrics()->GetNumberOfItems()
void GetMaxErrors(double *errors);
protected:
vtkGenericCellTessellator();
~vtkGenericCellTessellator();
// Description:
// 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)
// \pre leftPoint_exists: leftPoint!=0
// \pre midPoint_exists: midPoint!=0
// \pre rightPoint_exists: rightPoint!=0
// \pre clamped_alpha: alpha>0 && alpha<1
// \pre valid_size: sizeof(leftPoint)=sizeof(midPoint)=sizeof(rightPoint)
// =GetAttributeCollection()->GetNumberOfPointCenteredComponents()+6
int RequiresEdgeSubdivision(double *left, double *mid, double *right,
double alpha);
// Description:
// 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.
// \pre leftPoint_exists: leftPoint!=0
// \pre midPoint_exists: midPoint!=0
// \pre rightPoint_exists: rightPoint!=0
// \pre clamped_alpha: alpha>0 && alpha<1
// \pre valid_size: sizeof(leftPoint)=sizeof(midPoint)=sizeof(rightPoint)
// =GetAttributeCollection()->GetNumberOfPointCenteredComponents()+6
virtual void UpdateMaxError(double *leftPoint, double *midPoint,
double *rightPoint, double alpha);
// Description:
// Reset the maximal error of each error metric. The purpose of the maximal
// error is to measure the quality of a fixed subdivision.
void ResetMaxErrors();
// Description:
// List of error metrics. Collection of vtkGenericSubdivisionErrorMetric
vtkCollection *ErrorMetrics;
// Description:
// Send the current cell to error metrics. Should be called at the beginning
// of the implementation of Tessellate(), Triangulate()
// or TessellateFace()
// \pre cell_exists: cell!=0
void SetGenericCell(vtkGenericAdaptorCell *cell);
vtkGenericDataSet *DataSet;
int Measurement; // if true, measure the quality of the fixed subdivision.
double *MaxErrors; // max error for each error metric, for measuring the
// quality of a fixed subdivision.
int MaxErrorsCapacity;
private:
vtkGenericCellTessellator(const vtkGenericCellTessellator&); // Not implemented.
void operator=(const vtkGenericCellTessellator&); // Not implemented.
};
#endif