//C++ header - Open Scene Graph - Copyright (C) 1998-2001 Robert Osfield
//Distributed under the terms of the GNU Library General Public License (LGPL)
//as published by the Free Software Foundation.

#ifndef OSG_ANIMATIONPATH
#define OSG_ANIMATIONPATH 1

#include <osg/Matrix>
#include <osg/Quat>
#include <osg/Transform>

#include <map>

namespace osg {

/** AnimationPath for specify the time varying transformation pathway to use when update camera and model objects.
  * Subclassed from Transform::ComputeTransformCallback allows AnimationPath to
  * be attached directly to Transform nodes to move subgraphs around the scene.
*/
class SG_EXPORT AnimationPath : public Transform::ComputeTransformCallback
{
    public:
    
        AnimationPath() {}

        /** get the local transformation matrix for a point in time.*/        
        virtual bool getMatrix(double time,Matrix& matrix) const;

        /** get the local inverse transformation matrix for a point in time.*/        
        virtual bool getInverse(double time,Matrix& matrix) const;
        
        /** Get the transformation matrix which moves from local coords to world coords.*/
        virtual const bool computeLocalToWorldMatrix(Matrix& matrix,const Transform* transform, NodeVisitor* nv) const;
       
        /** Get the transformation matrix which moves from world coords to local coords.*/
        virtual const bool computeWorldToLocalMatrix(Matrix& matrix,const Transform* transform, NodeVisitor* nv) const;

        struct Key
        {
            Key() {}

            Key(const osg::Vec3& position, const osg::Quat& rotation, const osg::Vec3& scale):
                _position(position),
                _rotation(rotation),
                _scale(scale) {}
        
            osg::Vec3 _position;
            osg::Quat _rotation;
            osg::Vec3 _scale;
            
            inline void interpolate(const float ratio,const Key& first, const Key& second)
            {
                float one_minus_ratio = 1.0f-ratio;
                _position = first._position*one_minus_ratio + second._position*ratio;
                _rotation.slerp(ratio,first._rotation,second._rotation);
                _scale = first._scale*one_minus_ratio + second._scale*ratio;
            }
            
            inline void getMatrix(Matrix& matrix) const
            {
                matrix.makeScale(_scale);
                matrix.postMult(_rotation.getMatrix());
                matrix.postMult(osg::Matrix::translate(_position));
            }

            inline void getInverse(Matrix& matrix) const
            {
                matrix.makeScale(1.0f/_scale.x(),1.0f/_scale.y(),1.0f/_scale.y());
                matrix.postMult(_rotation.inverse().getMatrix());
                matrix.postMult(osg::Matrix::translate(-_position));
            }
        };
        
        
        void insert(double time,const Key& key);

    protected:
    
        virtual ~AnimationPath() {}

        typedef std::map<double,Key> TimeKeyMap;
        
        TimeKeyMap _timeKeyMap;

};

}

#endif