#ifndef OSG_FOG
#define OSG_FOG 1

#include <osg/Types>
#include <osg/Vec4>
#include <osg/StateAttribute>
#include <osg/StateSet>

namespace osg {


/** Fog - encapsulates OpenGL fog state. */ 
class SG_EXPORT Fog : public StateAttribute
{
    public :

        Fog();

        META_StateAttribute(Fog,FOG);
        
        /** return -1 if *this < *rhs, 0 if *this==*rhs, 1 if *this>*rhs.*/
        virtual int compare(const StateAttribute& sa) const
        {
            // check the types are equal and then create the rhs variable
            // used by the COMPARE_StateAttribute_Paramter macro's below.
            COMPARE_StateAttribute_Types(Fog,sa)

            // compare each paramter in turn against the rhs.
            COMPARE_StateAttribute_Parameter(_mode)
            COMPARE_StateAttribute_Parameter(_density)
            COMPARE_StateAttribute_Parameter(_start)
            COMPARE_StateAttribute_Parameter(_end)
            COMPARE_StateAttribute_Parameter(_color)

            return 0; // passed all the above comparison macro's, must be equal.
        }

        virtual void setStateSetModes(StateSet& ds,const GLModeValue value) const
        {
            ds.setMode(GL_FOG,value);
        }

        enum Mode {
            LINEAR = GL_LINEAR,
            EXP    = GL_EXP,
            EXP2   = GL_EXP2
        };

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

        inline void  setDensity( const float density )  { _density = density; }
        inline const float getDensity() const           { return _density; }

        inline void  setStart( const float start )      { _start = start; }
        inline const float getStart() const             { return _start; }

        inline void  setEnd( const float end )          { _end = end; }
        inline const float getEnd() const               { return _end; }

        inline void  setColor( const Vec4 &color )      { _color = color; }
        inline const Vec4& getColor() const             { return _color; }

        virtual void apply(State& state) const;

    protected :

        virtual ~Fog();

        Mode   _mode;
        float  _density;
        float  _start;
        float  _end;
        Vec4 _color;
};

};

#endif