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

  Program:   Visualization Toolkit
  Module:    vtkQuaternionInterpolator.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   vtkQuaternionInterpolator
 * @brief   interpolate a quaternion
 *
 * This class is used to interpolate a series of quaternions representing
 * the rotations of a 3D object.  The interpolation may be linear in form
 * (using spherical linear interpolation SLERP), or via spline interpolation
 * (using SQUAD). In either case the interpolation is specialized to
 * quaternions since the interpolation occurs on the surface of the unit
 * quaternion sphere.
 *
 * To use this class, specify at least two pairs of (t,q[4]) with the
 * AddQuaternion() method.  Next interpolate the tuples with the
 * InterpolateQuaternion(t,q[4]) method, where "t" must be in the range of
 * (t_min,t_max) parameter values specified by the AddQuaternion() method (t
 * is clamped otherwise), and q[4] is filled in by the method.
 *
 * There are several important background references. Ken Shoemake described
 * the practical application of quaternions for the interpolation of rotation
 * (K. Shoemake, "Animating rotation with quaternion curves", Computer
 * Graphics (Siggraph '85) 19(3):245--254, 1985). Another fine reference
 * (available on-line) is E. B. Dam, M. Koch, and M. Lillholm, Technical
 * Report DIKU-TR-98/5, Dept. of Computer Science, University of Copenhagen,
 * Denmark.
 *
 * @warning
 * Note that for two or less quaternions, Slerp (linear) interpolation is
 * performed even if spline interpolation is requested. Also, the tangents to
 * the first and last segments of spline interpolation are (arbitrarily)
 * defined by repeating the first and last quaternions.
 *
 * @warning
 * There are several methods particular to quaternions (norms, products,
 * etc.) implemented interior to this class. These may be moved to a separate
 * quaternion class at some point.
 *
 * @sa
 * vtkQuaternion
*/

#ifndef vtkQuaternionInterpolator_h
#define vtkQuaternionInterpolator_h

#include "vtkCommonMathModule.h" // For export macro
#include "vtkObject.h"

class vtkQuaterniond;
class vtkQuaternionList;

class VTKCOMMONMATH_EXPORT vtkQuaternionInterpolator : public vtkObject
{
public:
  vtkTypeMacro(vtkQuaternionInterpolator, vtkObject);
  void PrintSelf(ostream& os, vtkIndent indent) override;

  /**
   * Instantiate the class.
   */
  static vtkQuaternionInterpolator* New();

  /**
   * Return the number of quaternions in the list of quaternions to be
   * interpolated.
   */
  int GetNumberOfQuaternions();

  //@{
  /**
   * Obtain some information about the interpolation range. The numbers
   * returned (corresponding to parameter t, usually thought of as time)
   * are undefined if the list of transforms is empty. This is a convenience
   * method for interpolation.
   */
  double GetMinimumT();
  double GetMaximumT();
  //@}

  /**
   * Reset the class so that it contains no data; i.e., the array of (t,q[4])
   * information is discarded.
   */
  void Initialize();

  //@{
  /**
   * Add another quaternion to the list of quaternions to be interpolated.
   * Note that using the same time t value more than once replaces the
   * previous quaternion at t. At least one quaternions must be added to
   * define an interpolation functions.
   */
  void AddQuaternion(double t, const vtkQuaterniond& q);
  void AddQuaternion(double t, double q[4]);
  //@}

  /**
   * Delete the quaternion at a particular parameter t. If there is no
   * quaternion tuple defined at t, then the method does nothing.
   */
  void RemoveQuaternion(double t);

  //@{
  /**
   * Interpolate the list of quaternions and determine a new quaternion
   * (i.e., fill in the quaternion provided). If t is outside the range of
   * (min,max) values, then t is clamped to lie within the range.
   */
  void InterpolateQuaternion(double t, vtkQuaterniond& q);
  void InterpolateQuaternion(double t, double q[4]);
  //@}

  /**
   * Enums to control the type of interpolation to use.
   */
  enum {INTERPOLATION_TYPE_LINEAR=0,
        INTERPOLATION_TYPE_SPLINE
  };

  //@{
  /**
   * Specify which type of function to use for interpolation. By default
   * (SetInterpolationFunctionToSpline()), cubic spline interpolation using a
   * modified Kochanek basis is employed. Otherwise, if
   * SetInterpolationFunctionToLinear() is invoked, linear spherical interpolation
   * is used between each pair of quaternions.
   */
  vtkSetClampMacro(InterpolationType,int,INTERPOLATION_TYPE_LINEAR,
                   INTERPOLATION_TYPE_SPLINE);
  vtkGetMacro(InterpolationType,int);
  void SetInterpolationTypeToLinear()
    {this->SetInterpolationType(INTERPOLATION_TYPE_LINEAR);}
  void SetInterpolationTypeToSpline()
    {this->SetInterpolationType(INTERPOLATION_TYPE_SPLINE);}
  //@}

protected:
  vtkQuaternionInterpolator();
  ~vtkQuaternionInterpolator() override;

  // Specify the type of interpolation to use
  int InterpolationType;

  // Internal variables for interpolation functions
  vtkQuaternionList *QuaternionList; //used for linear quaternion interpolation

private:
  vtkQuaternionInterpolator(const vtkQuaternionInterpolator&) = delete;
  void operator=(const vtkQuaternionInterpolator&) = delete;

};

#endif
