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// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-License-Identifier: BSD-3-Clause
/**
* @class vtkPolyDataPointSampler
* @brief generate points from vtkPolyData
*
* vtkPolyDataPointSampler generates points from input vtkPolyData. The
* filter has two modes of operation: random point generation, or regular
* point generation. In random generation mode, points are generated in each
* polygonal entity using a random approach. In regular generation mode, the
* points are placed approximately a specified distance apart. Optionally,
* the points attributes can be interpolated from the generating vertices,
* edges, and polygons.
*
* In regular point generation mode, this filter functions as follows. First,
* it regurgitates all input points, then it samples all lines, plus edges
* associated with the input polygons and triangle strips to produce edge
* points. Finally, the interiors of polygons and triangle strips are
* subsampled to produce points. All of these operations can be enabled or
* disabled separately. Note that this algorithm only approximately generates
* points the specified distance apart. Generally the point density is finer
* than requested.
*
* In random point generation mode, this filter functions as follows. First,
* it randomly regurgitates all input points (if enabled), then it randomly
* samples all lines, plus edges associated with the input polygons and
* triangle strips to produce edge points (if enabled). Finally, the
* interiors of polygons and triangle strips are randomly subsampled to
* produce points. All of these operations can be enabled or disabled
* separately. Note that this algorithm only approximately generates points
* the specified distance apart. Generally the point density is finer than
* requested. Also note that the result is not truly random due to the
* constraints of the mesh construction.
*
* @warning
* Although this algorithm processes general polygons. it does so by performing
* a fan triangulation. This may produce poor results, especially for concave
* polygons. For better results, use a triangle filter to pre-tesselate
* polygons.
*
* @warning
* In random point generation mode, producing random edges and vertex points
* from polygons and triangle strips is less random than is typically
* desirable. You may wish to disable vertex and edge point generation for a
* result that is closer to random.
*
* @warning
* Point generation can be useful in a variety of applications. For example,
* generating seed points for glyphing or streamline generation. Another
* useful application is generating points for implicit modeling. In many
* cases implicit models can be more efficiently generated from points than
* from polygons or other primitives.
*
* @warning
* When sampling polygons of five sides or more, the polygon is triangulated.
* This can result in variations in point density near tessellation boundaries.
*
* @sa
* vtkTriangleFilter vtkImplicitModeller
*/
#ifndef vtkPolyDataPointSampler_h
#define vtkPolyDataPointSampler_h
#include "vtkEdgeTable.h" // for sampling edges
#include "vtkFiltersModelingModule.h" // For export macro
#include "vtkNew.h" // for data members
#include "vtkPolyDataAlgorithm.h"
VTK_ABI_NAMESPACE_BEGIN
class VTKFILTERSMODELING_EXPORT vtkPolyDataPointSampler : public vtkPolyDataAlgorithm
{
public:
/**
* Instantiate this class.
*/
static vtkPolyDataPointSampler* New();
///@{
/**
* Standard macros for type information and printing.
*/
vtkTypeMacro(vtkPolyDataPointSampler, vtkPolyDataAlgorithm);
void PrintSelf(ostream& os, vtkIndent indent) override;
///@}
///@{
/**
* Set/Get the approximate distance between points. This is an absolute
* distance measure. The default is 0.01.
*/
vtkSetClampMacro(Distance, double, 0.0, VTK_FLOAT_MAX);
vtkGetMacro(Distance, double);
///@}
/**
* Specify how points are to be generated.
*/
enum
{
REGULAR_GENERATION,
RANDOM_GENERATION
};
///@{
/**
* Specify/retrieve the type of point generation: either regular point
* generation or random point generation. By default, regular point
* generation is used.
*/
vtkSetClampMacro(PointGenerationMode, int, REGULAR_GENERATION, RANDOM_GENERATION);
vtkGetMacro(PointGenerationMode, int);
void SetPointGenerationModeToRegular() { this->SetPointGenerationMode(REGULAR_GENERATION); }
void SetPointGenerationModeToRandom() { this->SetPointGenerationMode(RANDOM_GENERATION); }
///@}
///@{
/**
* Specify/retrieve a boolean flag indicating whether cell vertex points should
* be output.
*/
vtkGetMacro(GenerateVertexPoints, bool);
vtkSetMacro(GenerateVertexPoints, bool);
vtkBooleanMacro(GenerateVertexPoints, bool);
///@}
///@{
/**
* Specify/retrieve a boolean flag indicating whether cell edges should
* be sampled to produce output points. The default is true.
*/
vtkGetMacro(GenerateEdgePoints, bool);
vtkSetMacro(GenerateEdgePoints, bool);
vtkBooleanMacro(GenerateEdgePoints, bool);
///@}
///@{
/**
* Specify/retrieve a boolean flag indicating whether cell interiors should
* be sampled to produce output points. The default is true.
*/
vtkGetMacro(GenerateInteriorPoints, bool);
vtkSetMacro(GenerateInteriorPoints, bool);
vtkBooleanMacro(GenerateInteriorPoints, bool);
///@}
///@{
/**
* Specify/retrieve a boolean flag indicating whether cell vertices should
* be generated. Cell vertices are useful if you actually want to display
* the points (that is, for each point generated, a vertex is generated).
* Recall that VTK only renders vertices and not points. The default is
* true.
*/
vtkGetMacro(GenerateVertices, bool);
vtkSetMacro(GenerateVertices, bool);
vtkBooleanMacro(GenerateVertices, bool);
///@}
///@{
/**
* Specify/retrieve a boolean flag indicating whether point data should be
* interpolated onto the newly generated points. If enabled, points
* generated from existing vertices will carry the vertex point data;
* points generated from edges will interpolate point data along each edge;
* and interior point data (inside triangles, polygons cells) will be
* interpolated from the cell vertices. By default this is off.
*/
vtkGetMacro(InterpolatePointData, bool);
vtkSetMacro(InterpolatePointData, bool);
vtkBooleanMacro(InterpolatePointData, bool);
///@}
protected:
vtkPolyDataPointSampler();
~vtkPolyDataPointSampler() override = default;
int RequestData(vtkInformation*, vtkInformationVector**, vtkInformationVector*) override;
double Distance;
int PointGenerationMode;
bool GenerateVertexPoints;
bool GenerateEdgePoints;
bool GenerateInteriorPoints;
bool GenerateVertices;
bool InterpolatePointData;
private:
vtkPolyDataPointSampler(const vtkPolyDataPointSampler&) = delete;
void operator=(const vtkPolyDataPointSampler&) = delete;
};
VTK_ABI_NAMESPACE_END
#endif
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