#ifndef OSG_BILLBOARD
#define OSG_BILLBOARD 1

#include <osg/Geode>

namespace osg {

/** Billboard - a Geode which orientates its child osg::GeoSet's to face
    the eye point.
    Typical uses are for trees, or particle explosions.
*/
class SG_EXPORT Billboard : public Geode
{
    public:

        enum Mode {
            AXIAL_ROT,
            POINT_ROT_EYE,
            POINT_ROT_WORLD
        };

        Billboard();
        
        virtual Object* clone() const           { return new Billboard(); }
        virtual bool isSameKindAs(Object* obj) { return dynamic_cast<Billboard*>(obj)!=NULL; }
        virtual const char* className() const   { return "Billboard"; }
        virtual void accept(NodeVisitor& nv)    { nv.apply(*this); }


        void setAxis(const Vec3& axis)          { _axis = axis; }
        void getAxis(Vec3& axis) const          { axis = _axis; }

        void setMode(Mode mode)                 { _mode = mode; }
        int getMode() const                     { return _mode; }

        void setPos(int i,const Vec3& pos)      { _positionList[i] = pos; }
        void getPos(int i,Vec3& pos) const      { pos = _positionList[i]; }
        
        /** Add GeoSet to Billboard with default position(0,0,0);
         *  If gset not NULL and is not contained in Billboard then increment its 
         *  reference count, and dirty the bounding box to cause it to recompute on 
         *  next getBound() and return true for success.  Otherwise return false.
         */
        virtual bool addGeoSet( GeoSet *gset );

        /** Add GeoSet to Geode at position pos.
         *  If gset not NULL and is not contained in Billboard then increment its 
         *  reference count, and dirty the bounding box to cause it to recompute on 
         *  next getBound() and return true for success.  Otherwise return false.
         */
        virtual bool addGeoSet(GeoSet *gset,const Vec3& pos);

        /** Remove GeoSet and associated position from Billboard.
         *  If gset is contained in Billboard then remove it from the geoset
         *  list and decrement its reference count, and dirty the 
         *  bounding box to cause it to recompute on next getBound() and
         *  return true for success.  If gset is not found then return false
         *  and do not the reference count of gset is left unchanged.
         */
        virtual bool removeGeoSet( GeoSet *gset );

        void calcRotation(const Vec3& eye_local, const Vec3& pos_local,Matrix& mat);
        void calcTransform(const Vec3& eye_local, const Vec3& pos_local,Matrix& mat);

    protected:

        virtual ~Billboard();

        virtual bool readLocalData(Input& fr);
        virtual bool writeLocalData(Output& fw);
        
        virtual bool computeBound( void );

        typedef std::vector<Vec3> PositionList;

        Mode            _mode;
        Vec3            _axis;
        PositionList    _positionList;

};

};

#endif