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

  Program:   Visualization Toolkit
  Module:    $RCSfile: vtkDashedStreamLine.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 vtkDashedStreamLine - generate constant-time dashed streamline in arbitrary dataset
// .SECTION Description
// vtkDashedStreamLine is a filter that generates a "dashed" streamline for 
// an arbitrary dataset. The streamline consists of a series of dashes, each 
// of which represents (approximately) a constant time increment. Thus, in the
// resulting visual representation, relatively long dashes represent areas of 
// high velocity, and small dashes represent areas of low velocity.
//
// vtkDashedStreamLine introduces the instance variable DashFactor. 
// DashFactor interacts with its superclass' instance variable StepLength to
// create the dashes. DashFactor is the percentage of the StepLength line 
// segment that is visible. Thus, if the DashFactor=0.75, the dashes will be 
// "three-quarters on" and "one-quarter off".

// .SECTION See Also
// vtkStreamer vtkStreamLine vtkStreamPoints

#ifndef __vtkDashedStreamLine_h
#define __vtkDashedStreamLine_h

#include "vtkStreamLine.h"

class VTK_GRAPHICS_EXPORT vtkDashedStreamLine : public vtkStreamLine
{
public:
  static vtkDashedStreamLine *New();
  vtkTypeRevisionMacro(vtkDashedStreamLine,vtkStreamLine);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // For each dash, specify the fraction of the dash that is "on". A factor
  // of 1.0 will result in a continuous line, a factor of 0.5 will result in 
  // dashed that are half on and half off.
  vtkSetClampMacro(DashFactor,double,0.01,1.0);
  vtkGetMacro(DashFactor,double);

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

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

  // the fraction of on versus off in dash
  double DashFactor;
  
private:
  vtkDashedStreamLine(const vtkDashedStreamLine&);  // Not implemented.
  void operator=(const vtkDashedStreamLine&);  // Not implemented.
};

#endif


