//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_LOD
#define OSG_LOD 1

#include <osg/Group>

namespace osg {

/** LOD - Level Of Detail group node which allows switching between children
    depending on distance from eye point.
    Typical uses are for load balancing - objects further away from
    the eye point are rendered at a lower level of detail, and at times
    of high stress on the graphics pipeline lower levels of detail can
    also be chosen.
*/
class SG_EXPORT LOD : public Group
{
    public :
        LOD() {}

        META_Node(LOD);

        virtual void traverse(NodeVisitor& nv);
        
        /** Sets the value of range list element index to range which
            is a floating point distance specified in world coordinates.
            Range list automatically expands to accommodate values beyond
            the current getNumRanges().*/
        void setRange(const unsigned int index, const float range);
        
        /** returns the range for specified index.*/
        inline const float getRange(const unsigned int index) const { return _rangeList[index]; }
        
        /** returns the number of ranges currently set.*/
        inline const int getNumRanges() const { return _rangeList.size(); }

        /** Sets the object-space point which defines the center of the osg::LOD.  
            center is affected by any transforms in the hierarchy above the osg::LOD.*/
        inline void setCenter(const Vec3 &center) { _center = center; }
        
        /** return the LOD center point. */
        inline const Vec3& getCenter() const { return _center; }


        /** return the child to traverse.
            Selected by the distance between the eye point in local
            coordinates and the LOD center, multiplied by the bias.*/ 
        const int evaluate(const Vec3& eye_local,const float bias=1.0f) const;


    protected :
        virtual ~LOD() {}

        typedef std::vector<float> RangeList;
        RangeList _rangeList;
        RangeList _rangeList2;

        Vec3 _center;

};

};

#endif