/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield 
 *
 * This library is open source and may be redistributed and/or modified under  
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 * OpenSceneGraph Public License for more details.
*/

#ifndef OSG_CLAMPCOLOR
#define OSG_CLAMPCOLOR 1

#include <osg/StateAttribute>

#ifndef GL_ARB_color_buffer_float
#define GL_RGBA_FLOAT_MODE_ARB                  0x8820
#define GL_CLAMP_VERTEX_COLOR_ARB               0x891A
#define GL_CLAMP_FRAGMENT_COLOR_ARB             0x891B
#define GL_CLAMP_READ_COLOR_ARB                 0x891C
#define GL_FIXED_ONLY_ARB                       0x891D
#endif

namespace osg {

/** Encapsulates OpenGL ClampColor state. */
class OSG_EXPORT ClampColor : public StateAttribute
{
    public :

        enum Target {
          CLAMP_VERTEX_COLOR   = GL_CLAMP_VERTEX_COLOR_ARB,
          CLAMP_FRAGMENT_COLOR = GL_CLAMP_FRAGMENT_COLOR_ARB,
          CLAMP_READ_COLOR     = GL_CLAMP_READ_COLOR_ARB
        };

        enum Mode {
          FIXED_ONLY = GL_FIXED_ONLY_ARB,
          FALSE      = GL_FALSE,
          TRUE       = GL_TRUE
        };


        ClampColor();
        
        ClampColor(Target target, Mode mode);

        /** Copy constructor using CopyOp to manage deep vs shallow copy. */
        ClampColor(const ClampColor& trans,const CopyOp& copyop=CopyOp::SHALLOW_COPY):
            StateAttribute(trans,copyop),
            _target(trans._target),
            _mode(trans._mode) {}

        META_StateAttribute(osg, ClampColor,CLAMPCOLOR);
        
        /** Return -1 if *this < *rhs, 0 if *this==*rhs, 1 if *this>*rhs. */
        virtual int compare(const StateAttribute& sa) const
        {
            // Check for equal types, then create the rhs variable
            // used by the COMPARE_StateAttribute_Paramter macros below.
            COMPARE_StateAttribute_Types(ClampColor,sa)

            // Compare each parameter in turn against the rhs.
            COMPARE_StateAttribute_Parameter(_target)
            COMPARE_StateAttribute_Parameter(_mode)

            return 0; // Passed all the above comparison macros, so must be equal.
        }

        inline void setTarget(Target target)
        {
            _target = target;
        }

        inline Target getTarget() const { return _target; }


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

        inline Mode getMode() const { return _mode; }

        
        virtual void apply(State& state) const;
        /** Encapsulates queries of extension availability, obtains extension
          * function pointers, and provides convinience wrappers for
          * calling extension functions. */        
        class OSG_EXPORT Extensions : public osg::Referenced
        {
            public:
                Extensions(unsigned int contextID);

                Extensions(const Extensions& rhs);
                
                void lowestCommonDenominator(const Extensions& rhs);
                
                void setupGLExtenions(unsigned int contextID);

                void setClampColorSupported(bool flag) { _isClampColorSupported=flag; }
                bool isClampColorSupported() const { return _isClampColorSupported; }
                
                void setClampColorProc(void* ptr) { _glClampColor = ptr; }
                void glClampColor(GLenum target, GLenum mode) const;

            protected:

                ~Extensions() {}
                
                bool    _isClampColorSupported;

                void*   _glClampColor;

        };
        
        /** Returns the Extensions object for the given context.
          * If createIfNotInitalized is true and the Exentsions object doesn't
          * exist, getExtensions() creates it on the given context.
          * Returns NULL if createIfNotInitalized is false and the Extensions
          * object doesn't exist. */
        static Extensions* getExtensions(unsigned int contextID,bool createIfNotInitalized);

        /** setExtensions() allows users to override the extensions across graphics contexts.
          * Typically used when you have different extensions supported across graphics pipes,
          * but need to ensure that they all use the same low common denominator extensions. */
        static void setExtensions(unsigned int contextID,Extensions* extensions);


    protected :

        virtual ~ClampColor();


        Target _target;
        Mode   _mode;
};

}

#endif