VTK-5.0.0/Filtering/vtkSpline.h

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

  Program:   Visualization Toolkit
  Module:    $RCSfile: vtkSpline.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 vtkSpline - spline abstract class for interpolating splines
// .SECTION Description
// vtkSpline interpolates a set of data points (i.e., interpolation means
// that the spline passes through the points).  vtkSpline is an abstract
// class: its subclasses vtkCardinalSpline and vtkKochenekSpline do the
// interpolation. Note that this spline maps the 1D parametric coordinate
// t into a single value x. Thus if you want to use the spline to 
// interpolate points (i.e. x[3]), you have to create three splines for
// each of the x-y-z coordinates. Fortunately, the vtkParametricSpline
// class does this for you.
//
// Typically a spline is used by adding a sequence of parametric coordinate /
// data (t,x) values followed by use of an evaluation function (e.g.,
// vtkCardinalSpline::Evaluate()).  Since these splines are 1D, a point in
// this context is an independent / dependent variable pair. 
//
// Splines can also be set up to be closed or open. Closed splines continue
// from the last point to the first point with continuous function and 
// derivative values. (You don't need to duplicate the first point to close
// the spline, just set ClosedOn.) 
//
// This implementation of splines does not use a normalized parametric
// coordinate. If the spline is open, then the parameter space is (tMin <= t
// <= tMax) where tMin and tMax are the minimum and maximum parametric values
// seen when performing AddPoint(). If the spline is closed, then the
// parameter space is (tMin <= t <= (tMax+1)) where tMin and tMax are the
// minimum and maximum parametric values seen when performing AddPoint().
// Note, however, that this behavior can be changed by explicitly setting
// the ParametricRange(tMin,tMax). If set, the parameter space remains
// (tMin <= t <= tMax), except that additions of data with parametric
// values outside this range are clamped within this range.

// .SECTION See Also
// vtkCardinalSpline vtkKochenekSpline vtkParametricSpline
// vtkParametricFunctionSource


#ifndef __vtkSpline_h
#define __vtkSpline_h

#include "vtkObject.h"

class vtkPiecewiseFunction;

class VTK_FILTERING_EXPORT vtkSpline : public vtkObject
{
public:
  vtkTypeRevisionMacro(vtkSpline,vtkObject);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Set/Get the parametric range. If not set, the range is determined
  // implicitly by keeping track of the (min,max) parameter values for
  // t. If set, the AddPoint() method will clamp the t value to lie
  // within the specified range.
  void SetParametricRange(double tMin, double tMax);
  void SetParametricRange(double tRange[2])
    {this->SetParametricRange(tRange[0],tRange[1]);}
  void GetParametricRange(double tRange[2]) const;

  // Description:
  // Set/Get ClampValue. If On, results of the interpolation will be
  // clamped to the min/max of the input data.
  vtkSetMacro(ClampValue,int);
  vtkGetMacro(ClampValue,int);
  vtkBooleanMacro(ClampValue,int);

  // Description:
  // Compute the coefficients for the spline.
  virtual void Compute () = 0;

  // Description:
  // Interpolate the value of the spline at parametric location of t.
  virtual double Evaluate (double t) = 0;

  // Description:
  // Return the number of points inserted thus far.
  int GetNumberOfPoints();

  // Description:
  // Add a pair of points to be fit with the spline.
  void AddPoint (double t, double x);

  // Description:
  // Remove a point from the data to be fit with the spline.
  void RemovePoint (double t);
 
  // Description:
  // Remove all points from the data.
  void RemoveAllPoints ();

  // 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:
  // 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);

  // Description:
  // Return the MTime also considering the Piecewise function.
  unsigned long GetMTime();

  // Description:
  // Deep copy of spline data.
  virtual void DeepCopy(vtkSpline *s);

protected:
  vtkSpline();
  ~vtkSpline();

  unsigned long ComputeTime;
  int ClampValue;
  double *Intervals;
  double *Coefficients;
  int LeftConstraint;
  double LeftValue;
  int RightConstraint;
  double RightValue;
  vtkPiecewiseFunction *PiecewiseFunction;
  int Closed;
  
  // Explicitly specify the parametric range.
  double ParametricRange[2];

  // Helper methods
  double ComputeLeftDerivative();
  double ComputeRightDerivative();
  int FindIndex(int size, double t);

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

#endif