/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2005 Robert Osfield 
 *
 * This library is open source and may be redistributed and/or modified under  
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 * OpenSceneGraph Public License for more details.
*/

#ifndef OSGGA_UFO_MANIPULATOR_DEF
#define OSGGA_UFO_MANIPULATOR_DEF 1

#include <iostream>

#include <osgGA/MatrixManipulator>
#include <osg/Node>
#include <osg/Matrix>

    /**
      \class osgGA::UFOManipulator
      \brief A UFO manipulator driven with keybindings.

      The UFOManipulator is better suited for applications that employ 
      architectural walk-throughs, or situations where the eyepoint motion
      model must move slowly, deliberately and well controlled.  

      The UFO Manipulator allows the following movements with the listed
      Key combinations:
        \param UpArrow          Acceleration forward.
        \param DownArrow        Acceleration backward (or deceleration forward).
        \param LeftArrow        Rotate view and direction of travel to the left.
        \param RightArrow       Rotate view and direction of travel to the right.
        \param SpaceBar         Brake.  Gradually decelerates linear and rotational movement.
        \param Shift/UpArrow    Accelerate up.
        \param Shift/DownArrow  Accelerate down.
        \param Shift/LeftArrow  Accelerate (linearly) left.
        \param Shift/RightArrow Accelerate (linearly) right.
        \param Shift/SpaceBar   Instant brake.  Immediately stop all linear and rotational movement.

    When the Shift key is released, up, down, linear left and/or linear right movement is decelerated.

        \param Ctrl/UpArrow     Rotate view (but not direction of travel) up.
        \param Ctrl/DownArrow   Rotate view (but not direction of travel) down.
        \param Ctrl/LeftArrow   Rotate view (but not direction of travel) left.
        \param Ctrl/RightArrow  Rotate view (but not direction of travel) right.
        \param Ctrl/Return      Straightens out the view offset.

    */

namespace osgGA {

class OSGGA_EXPORT UFOManipulator : public osgGA::MatrixManipulator
{

    public:
        /** Default constructor */
        UFOManipulator();

        /** return className
          \return returns constant "UFO"
          */
        virtual const char* className() const;

        /** Set the current position with a matrix 
          \param matrix  A viewpoint matrix.
         */
        virtual void setByMatrix( const osg::Matrixd &matrix ) ;

        /** Set the current position with the invers matrix
          \param invmat The inverse of a viewpoint matrix
          */
        virtual void setByInverseMatrix( const osg::Matrixd &invmat);

        /** Get the current viewmatrix */
        virtual osg::Matrixd getMatrix() const;

        /** Get the current inverse view matrix */
        virtual osg::Matrixd getInverseMatrix() const ;

        /** Set the  subgraph this manipulator is driving the eye through.
            \param node     root of subgraph
         */
        virtual void setNode(osg::Node* node);

        /** Get the root node of the subgraph this manipulator is driving the eye through (const)*/
        virtual const osg::Node* getNode() const;

        /** Get the root node of the subgraph this manipulator is driving the eye through */
        virtual osg::Node* getNode();

        /** Computes the home position based on the extents and scale of the 
            scene graph rooted at node */
        virtual void computeHomePosition();

        /** Sets the viewpoint matrix to the home position */
        virtual void home(const osgGA::GUIEventAdapter&, osgGA::GUIActionAdapter&) ;
        void home(double);

        virtual void init(const GUIEventAdapter& ,GUIActionAdapter&);

        /** Handles incoming osgGA events */
        bool handle(const osgGA::GUIEventAdapter& ea,osgGA::GUIActionAdapter &aa);

        /** Reports Usage parameters to the application */
        void getUsage(osg::ApplicationUsage& usage) const;

        /** Report the current position as LookAt vectors */
        void getCurrentPositionAsLookAt( osg::Vec3 &eye, osg::Vec3 &center, osg::Vec3 &up );

        protected:

    private:
        osg::ref_ptr<osg::Node> _node;
        float       _viewAngle;
        osg::Matrixd _matrix;
        osg::Matrixd _inverseMatrix;
        osg::Matrixd _offset;

        double    _minHeightAboveGround;
        double    _minDistanceInFront;

        double    _speedEpsilon;
        double    _forwardSpeed;
        double    _sideSpeed;
        double    _upSpeed;
        double    _speedAccelerationFactor;
        double    _speedDecelerationFactor;

        bool      _decelerateUpSideRate;

        double    _directionRotationEpsilon;
        double    _directionRotationRate;
        double    _directionRotationAcceleration;
        double    _directionRotationDeceleration;

        double    _viewOffsetDelta;
        double    _pitchOffsetRate;
        double    _pitchOffset;
        double    _yawOffsetRate;
        double    _yawOffset;

        double    _t0;
        double    _dt;
        osg::Vec3 _direction;
        osg::Vec3 _position;


        bool _shift;
        bool _ctrl;
        bool _decelerateOffsetRate;

        bool _straightenOffset;

        void _stop();
        void _keyDown( const osgGA::GUIEventAdapter &ea, osgGA::GUIActionAdapter &);
        void _keyUp( const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter &);
        void _frame(const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter &);

        void _adjustPosition();
};

}

#endif