/*=========================================================================

  Program:   Visualization Toolkit
  Module:    $RCSfile: vtkPolyDataPointSampler.h,v $

  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 vtkPolyDataPointSampler - generate points from vtkPolyData
// .SECTION Description
// vtkPolyDataPointSampler generates points from input vtkPolyData. The
// points are placed approximately a specified distance apart.
//
// This filter functions as follows. First, it regurgitates all input points,
// then 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
// functiona 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.
//
// .SECTION Caveats
// 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.

// .SECTION See Also
// vtkImplicitModeller

#ifndef __vtkPolyDataPointSampler_h
#define __vtkPolyDataPointSampler_h

#include "vtkPolyDataAlgorithm.h"

class VTK_GRAPHICS_EXPORT vtkPolyDataPointSampler : public vtkPolyDataAlgorithm 
{
public:
  // Description:
  // Instantiate this class.
  static vtkPolyDataPointSampler *New();

  // Description:
  // Standard macros for type information and printing.
  vtkTypeRevisionMacro(vtkPolyDataPointSampler,vtkPolyDataAlgorithm);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Set/Get the approximate distance between points. This is an absolute
  // distance measure.
  vtkSetClampMacro(Distance,double,0.0,VTK_LARGE_FLOAT);
  vtkGetMacro(Distance,double);
  
  // Description:
  // Specify/retrieve a boolean flag indicating whether cell vertex points should
  // be output.
  vtkGetMacro(GenerateVertexPoints,int);  
  vtkSetMacro(GenerateVertexPoints,int);  
  vtkBooleanMacro(GenerateVertexPoints,int);  

  // Description:
  // Specify/retrieve a boolean flag indicating whether cell edges should
  // be sampled to produce output points.
  vtkGetMacro(GenerateEdgePoints,int);  
  vtkSetMacro(GenerateEdgePoints,int);  
  vtkBooleanMacro(GenerateEdgePoints,int);  

  // Description:
  // Specify/retrieve a boolean flag indicating whether cell interiors should
  // be sampled to produce output points.
  vtkGetMacro(GenerateInteriorPoints,int);  
  vtkSetMacro(GenerateInteriorPoints,int);  
  vtkBooleanMacro(GenerateInteriorPoints,int);  

  // Description:
  // 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.
  vtkGetMacro(GenerateVertices,int);  
  vtkSetMacro(GenerateVertices,int);  
  vtkBooleanMacro(GenerateVertices,int);  

protected:
  vtkPolyDataPointSampler();
  ~vtkPolyDataPointSampler() {}

  int RequestData(vtkInformation *, vtkInformationVector **, vtkInformationVector *);

  double Distance;
  double Distance2;
  
  int GenerateVertexPoints;
  int GenerateEdgePoints;
  int GenerateInteriorPoints;
  int GenerateVertices;

  void SampleEdge(vtkPoints *pts, double x0[3], double x1[3]);
  void SampleTriangle(vtkPoints *newPts, vtkPoints *inPts, 
                      vtkIdType *pts);
  void SamplePolygon(vtkPoints *newPts, vtkPoints *inPts, 
                      vtkIdType npts, vtkIdType *pts);

private:
  vtkPolyDataPointSampler(const vtkPolyDataPointSampler&);  // Not implemented.
  void operator=(const vtkPolyDataPointSampler&);  // Not implemented.
};

#endif
