//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_DEPTH
#define OSG_DEPTH 1

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

namespace osg {

/** Encapsulate OpenGL glDepthFunc/Mask/Range functions.
*/     
class SG_EXPORT Depth : public StateAttribute
{
    public :
    
    
        Depth();
        
        META_StateAttribute(Depth, DEPTH);
        
        /** 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(Depth,sa)

            // compare each paramter in turn against the rhs.
            COMPARE_StateAttribute_Parameter(_func)
            COMPARE_StateAttribute_Parameter(_depthWriteMask)
            COMPARE_StateAttribute_Parameter(_zNear)
            COMPARE_StateAttribute_Parameter(_zFar)

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

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

        enum Function
        {
            NEVER = GL_NEVER,
            LESS = GL_LESS,
            EQUAL = GL_EQUAL,
            LEQUAL = GL_LEQUAL,
            GREATER = GL_GREATER,
            NOTEQUAL = GL_NOTEQUAL,
            GEQUAL = GL_GEQUAL,
            ALWAYS = GL_ALWAYS
        };

        inline void setFunction(const Function func) { _func = func; }
        
        inline const Function getFunction() const { return _func; }
               

        inline void setWriteMask(const bool mask) { _depthWriteMask = mask; }
        
        inline const bool getWriteMask() const { return _depthWriteMask; }

        inline void setRange(const double zNear, const double zFar)
        {
            _zNear = zNear;
            _zFar = zFar;
        }

        inline const double getZNear() const { return _zNear; }
        inline const double getZFar() const { return _zFar; }

        virtual void apply(State& state) const;

    protected:
    
        virtual ~Depth();

        Function            _func;
        bool                _depthWriteMask;
        
        double              _zNear;
        double              _zFar;

};

};

#endif