#ifndef OSG_ALPHAFUNC
#define OSG_ALPHAFUNC 1

#include <osg/Export>
#include <osg/Object>
#include <osg/GL>

namespace osg {

/** Encapsulte OpenGL glAlphaFunc.
*/     
class SG_EXPORT AlphaFunc : public Object
{
    public :
    
        enum ComparisonFunction {
            NEVER = GL_NEVER,
            LESS = GL_LESS,
            EQUAL = GL_EQUAL,
            LEQUAL = GL_LEQUAL,
            GREATER = GL_GREATER,
            NOTEQUAL = GL_NOTEQUAL,
            GEQUAL = GL_GEQUAL,
            ALWAYS = GL_ALWAYS
        };
    
        AlphaFunc();
        static AlphaFunc* instance();
        virtual bool isSameKindAs(Object* obj) { return dynamic_cast<AlphaFunc*>(obj)!=NULL; }
        virtual Object* clone() const { return new AlphaFunc(); }
        virtual const char* className() const { return "AlphaFunc"; }
    
        void setFunction(ComparisonFunction func,float ref)
        {
            _comparisonFunc = func;
            _referenceValue = ref;
        }
        
        ComparisonFunction getFunction() const { return _comparisonFunc; }
        
        float getRefrenceValue() const { return _referenceValue; }
        
        static void enable();
        static void disable();
        
        void apply();
        
    protected:
    
        virtual ~AlphaFunc();

        virtual bool readLocalData(Input& fr);
        virtual bool writeLocalData(Output& fw);
        
        bool matchFuncStr(const char* str,ComparisonFunction& func);
        const char* getFuncStr(ComparisonFunction func);

        ComparisonFunction _comparisonFunc;
        float _referenceValue;

};

};

#endif