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

  Program:   Visualization Toolkit
  Module:    vtkStreamLine.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   vtkStreamLine
 * @brief   generate streamline in arbitrary dataset
 *
 * vtkStreamLine is a filter that generates a streamline for an arbitrary
 * dataset. A streamline is a line that is everywhere tangent to the vector
 * field. Scalar values also are calculated along the streamline and can be
 * used to color the line. Streamlines are calculated by integrating from
 * a starting point through the vector field. Integration can be performed
 * forward in time (see where the line goes), backward in time (see where the
 * line came from), or in both directions. It also is possible to compute
 * vorticity along the streamline. Vorticity is the projection (i.e., dot
 * product) of the flow rotation on the velocity vector, i.e., the rotation
 * of flow around the streamline.
 *
 * vtkStreamLine defines the instance variable StepLength. This parameter
 * controls the time increment used to generate individual points along
 * the streamline(s). Smaller values result in more line
 * primitives but smoother streamlines. The StepLength instance variable is
 * defined in terms of time (i.e., the distance that the particle travels in
 * the specified time period). Thus, the line segments will be smaller in areas
 * of low velocity and larger in regions of high velocity. (NOTE: This is
 * different than the IntegrationStepLength defined by the superclass
 * vtkStreamer. IntegrationStepLength is used to control integration step
 * size and is expressed as a fraction of the cell length.) The StepLength
 * instance variable is important because subclasses of vtkStreamLine (e.g.,
 * vtkDashedStreamLine) depend on this value to build their representation.
 *
 * @sa
 * vtkStreamer vtkDashedStreamLine vtkStreamPoints
*/

#ifndef vtkStreamLine_h
#define vtkStreamLine_h

#include "vtkFiltersFlowPathsModule.h" // For export macro
#include "vtkStreamer.h"

#ifndef VTK_LEGACY_REMOVE

class VTKFILTERSFLOWPATHS_EXPORT vtkStreamLine : public vtkStreamer
{
public:
  vtkTypeMacro(vtkStreamLine,vtkStreamer);
  void PrintSelf(ostream& os, vtkIndent indent);

  /**
   * Construct object with step size set to 1.0.
   */
  static vtkStreamLine *New();

  //@{
  /**
   * Specify the length of a line segment. The length is expressed in terms of
   * elapsed time. Smaller values result in smoother appearing streamlines, but
   * greater numbers of line primitives.
   */
  vtkSetClampMacro(StepLength,double,0.000001,VTK_DOUBLE_MAX);
  vtkGetMacro(StepLength,double);
  //@}

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

  // Convert streamer array into vtkPolyData
  virtual int RequestData(vtkInformation *, vtkInformationVector **, vtkInformationVector *);

  // the length of line primitives
  double StepLength;

private:
  vtkStreamLine(const vtkStreamLine&) VTK_DELETE_FUNCTION;
  void operator=(const vtkStreamLine&) VTK_DELETE_FUNCTION;
};

#endif // VTK_LEGACY_REMOVE
#endif