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

  Program:   Visualization Toolkit
  Module:    $RCSfile: vtkParametricSpline.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 vtkParametricSpline - parametric function for 1D interpolating splines
// .SECTION Description
// vtkParametricSpline is a parametric function for 1D interpolating splines.
// vtkParametricSpline maps the single parameter u into a 3D point (x,y,z)
// using three instances of interpolating splines.  This family of 1D splines
// is quaranteed to be parameterized in the interval [0,1].  Attempting to
// evaluate outside this interval will cause the parameter u to be clamped in
// the range [0,1].
//
// When constructed, this class creates instances of vtkCardinalSpline for
// each of the x-y-z coordinates. The user may choose to replace these with
// their own instances of subclasses of vtkSpline.
//
// .SECTION Caveats
// If you wish to tessellate the spline, use the class 
// vtkParametricFunctionSource.
//
// .SECTION See Also
// vtkSpline vtkKochanekSpline vtkCardinalSpline

#ifndef __vtkParametricSpline_h
#define __vtkParametricSpline_h

class vtkSpline;
class vtkPoints;

#include "vtkParametricFunction.h"

class VTK_FILTERING_EXPORT vtkParametricSpline : public vtkParametricFunction
{
public:
  vtkTypeRevisionMacro(vtkParametricSpline,vtkParametricFunction);
  void PrintSelf(ostream& os, vtkIndent indent);
  
  // Description:
  // Construct the spline with the following parameters:
  // MinimumU = 0, MaximumU = 1, JoinU = 0 (unless the spline is
  // closed, then JoinU = 1), TwistU = 0, DerivativesSupplied = 0
  // (the other vtkParametricFunction parameters are ignored).
  static vtkParametricSpline *New();

  // Description
  // Return the parametric dimension of the class.
  virtual int GetDimension() {return 1;}

  // Description:
  // Evaluate the spline at parametric coordinate u[0] returning
  // the point coordinate Pt[3].
  virtual void Evaluate(double u[3], double Pt[3], double Du[9]);

  // Description:
  // Evaluate a scalar value at parametric coordinate u[0] and Pt[3].
  // The scalar value is just the parameter u[0].
  virtual double EvaluateScalar(double u[3], double Pt[3], double Du[9]);

  // Description:
  // By default, this class is constructed with three instances of
  // vtkCardinalSpline (for each of the x-y-z coordinate axes). The user may
  // choose to create and assign their own instances of vtkSpline.
  void SetXSpline(vtkSpline*);
  void SetYSpline(vtkSpline*);
  void SetZSpline(vtkSpline*);
  vtkGetObjectMacro(XSpline,vtkSpline);
  vtkGetObjectMacro(YSpline,vtkSpline);
  vtkGetObjectMacro(ZSpline,vtkSpline);

  // Description:
  // Specify the list of points defining the spline. Do this by 
  // specifying a vtkPoints array containing the points. Note that
  // the order of the points in vtkPoints is the order that the
  // splines will be fit.
  void SetPoints(vtkPoints*);
  vtkGetObjectMacro(Points,vtkPoints);

  // Description:
  // Control whether the spline is open or closed. A closed spline forms
  // a continuous loop: the first and last points are the same, and
  // derivatives are continuous.
  vtkSetMacro(Closed,int);
  vtkGetMacro(Closed,int);
  vtkBooleanMacro(Closed,int);

  // Description:
  // Control whether the spline is parameterized by length or by point index.
  // Default is by length.
  vtkSetMacro(ParameterizeByLength,int);
  vtkGetMacro(ParameterizeByLength,int);
  vtkBooleanMacro(ParameterizeByLength,int);   

  // Description:
  // Set the type of constraint of the left(right) end points. Four
  // constraints are available:
  //
  // 0: the first derivative at left(right) most point is determined
  // from the line defined from the first(last) two points.
  //
  // 1: the first derivative at left(right) most point is set to
  // Left(Right)Value.
  // 
  // 2: the second derivative at left(right) most point is set to
  // Left(Right)Value.
  // 
  // 3: the second derivative at left(right)most points is Left(Right)Value
  // times second derivative at first interior point.
  vtkSetClampMacro(LeftConstraint,int,0,3);
  vtkGetMacro(LeftConstraint,int);
  vtkSetClampMacro(RightConstraint,int,0,3);
  vtkGetMacro(RightConstraint,int);

  // Description:
  // The values of the derivative on the left and right sides. The value
  // is used only if the left(right) constraint is type 1-3.
  vtkSetMacro(LeftValue,double);
  vtkGetMacro(LeftValue,double);
  vtkSetMacro(RightValue,double);
  vtkGetMacro(RightValue,double);

protected:
  vtkParametricSpline();
  ~vtkParametricSpline();

  // Points definition
  vtkPoints *Points;

  // The interpolating splines for each of the x-y-z coordinates
  vtkSpline *XSpline;
  vtkSpline *YSpline;
  vtkSpline *ZSpline;

  // Supplemental variables
  int    Closed;
  int    LeftConstraint;
  int    RightConstraint;
  double LeftValue;
  double RightValue;
  int    ParameterizeByLength;

  // Initializing the spline
  unsigned long InitializeTime;
  int Initialize();
  
  // Internal variable for managing parametric coordinates
  double Length;
  double ClosedLength;
  
private:
  vtkParametricSpline(const vtkParametricSpline&);  // Not implemented.
  void operator=(const vtkParametricSpline&);  // Not implemented.
};

#endif
