/*
-----------------------------------------------------------------------------
This source file is part of OGRE
    (Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2014 Torus Knot Software Ltd

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
-----------------------------------------------------------------------------
*/
#ifndef __RotationalSpline_H__
#define __RotationalSpline_H__

#include "OgrePrerequisites.h"
#include "OgreQuaternion.h"
#include "OgreHeaderPrefix.h"

namespace Ogre {

    /** \addtogroup Core
    *  @{
    */
    /** \addtogroup Math
    *  @{
    */
    /** This class interpolates orientations (rotations) along a spline using 
        derivatives of quaternions.

        Like the SimpleSpline class, this class is about interpolating values 
        smoothly over a spline. Whilst SimpleSpline deals with positions (the normal
        sense we think about splines), this class interpolates orientations. The
        theory is identical, except we're now in 4-dimensional space instead of 3.
    @par
        In positional splines, we use the points and tangents on those points to generate
        control points for the spline. In this case, we use quaternions and derivatives
        of the quaternions (i.e. the rate and direction of change at each point). This is the
        same as SimpleSpline since a tangent is a derivative of a position. We effectively 
        generate an extra quaternion in between each actual quaternion which when take with 
        the original quaternion forms the 'tangent' of that quaternion.
    */
    class _OgreExport RotationalSpline
    {
    public:
        RotationalSpline();
        ~RotationalSpline();

        /** Adds a control point to the end of the spline. */
        void addPoint(const Quaternion& p);

        /** Gets the detail of one of the control points of the spline. */
        const Quaternion& getPoint(unsigned short index) const;

        /** Gets the number of control points in the spline. */
        unsigned short getNumPoints(void) const;

        /** Clears all the points in the spline. */
        void clear(void);

        /** Updates a single point in the spline. 

            This point must already exist in the spline.
        */
        void updatePoint(unsigned short index, const Quaternion& value);

        /** Returns an interpolated point based on a parametric value over the whole series.

            Given a t value between 0 and 1 representing the parametric distance along the
            whole length of the spline, this method returns an interpolated point.
        @param t Parametric value.
        @param useShortestPath Defines if rotation should take the shortest possible path
        */
        Quaternion interpolate(Real t, bool useShortestPath=true);

        /** Interpolates a single segment of the spline given a parametric value.
        @param fromIndex The point index to treat as t=0. fromIndex + 1 is deemed to be t=1
        @param t Parametric value
        @param useShortestPath Defines if rotation should take the shortest possible path
        */
        Quaternion interpolate(unsigned int fromIndex, Real t, bool useShortestPath=true);

        /** Tells the spline whether it should automatically calculate tangents on demand
            as points are added.

            The spline calculates tangents at each point automatically based on the input points.
            Normally it does this every time a point changes. However, if you have a lot of points
            to add in one go, you probably don't want to incur this overhead and would prefer to 
            defer the calculation until you are finished setting all the points. You can do this
            by calling this method with a parameter of 'false'. Just remember to manually call 
            the recalcTangents method when you are done.
        @param autoCalc If true, tangents are calculated for you whenever a point changes. If false, 
            you must call reclacTangents to recalculate them when it best suits.
        */
        void setAutoCalculate(bool autoCalc);

        /** Recalculates the tangents associated with this spline. 

            If you tell the spline not to update on demand by calling setAutoCalculate(false)
            then you must call this after completing your updates to the spline points.
        */
        void recalcTangents(void);

    private:

        bool mAutoCalc;



        std::vector<Quaternion> mPoints;
        std::vector<Quaternion> mTangents;

    };

    /** @} */
    /** @} */

}

#include "OgreHeaderSuffix.h"

#endif