#ifndef OSG_FBOEXTENSIONS
#define OSG_FBOEXTENSIONS 1

#include <osg/GL>
#include <osg/buffered_value>

#ifndef GL_EXT_framebuffer_object
#define GL_EXT_framebuffer_object 1
#define GL_FRAMEBUFFER_EXT                     0x8D40
#define GL_RENDERBUFFER_EXT                    0x8D41
#define GL_STENCIL_INDEX_EXT                   0x8D45
#define GL_STENCIL_INDEX1_EXT                  0x8D46
#define GL_STENCIL_INDEX4_EXT                  0x8D47
#define GL_STENCIL_INDEX8_EXT                  0x8D48
#define GL_STENCIL_INDEX16_EXT                 0x8D49
#define GL_RENDERBUFFER_WIDTH_EXT              0x8D42
#define GL_RENDERBUFFER_HEIGHT_EXT             0x8D43
#define GL_RENDERBUFFER_INTERNAL_FORMAT_EXT    0x8D44
#define GL_RENDERBUFFER_RED_SIZE_EXT           0x8D50
#define GL_RENDERBUFFER_GREEN_SIZE_EXT         0x8D51
#define GL_RENDERBUFFER_BLUE_SIZE_EXT          0x8D52
#define GL_RENDERBUFFER_ALPHA_SIZE_EXT         0x8D53
#define GL_RENDERBUFFER_DEPTH_SIZE_EXT         0x8D54
#define GL_RENDERBUFFER_STENCIL_SIZE_EXT       0x8D55
#define GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE_EXT            0x8CD0
#define GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME_EXT            0x8CD1
#define GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL_EXT          0x8CD2
#define GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_CUBE_MAP_FACE_EXT  0x8CD3
#define GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_3D_ZOFFSET_EXT     0x8CD4
#define GL_COLOR_ATTACHMENT0_EXT                0x8CE0
#define GL_COLOR_ATTACHMENT1_EXT                0x8CE1
#define GL_COLOR_ATTACHMENT2_EXT                0x8CE2
#define GL_COLOR_ATTACHMENT3_EXT                0x8CE3
#define GL_COLOR_ATTACHMENT4_EXT                0x8CE4
#define GL_COLOR_ATTACHMENT5_EXT                0x8CE5
#define GL_COLOR_ATTACHMENT6_EXT                0x8CE6
#define GL_COLOR_ATTACHMENT7_EXT                0x8CE7
#define GL_COLOR_ATTACHMENT8_EXT                0x8CE8
#define GL_COLOR_ATTACHMENT9_EXT                0x8CE9
#define GL_COLOR_ATTACHMENT10_EXT               0x8CEA
#define GL_COLOR_ATTACHMENT11_EXT               0x8CEB
#define GL_COLOR_ATTACHMENT12_EXT               0x8CEC
#define GL_COLOR_ATTACHMENT13_EXT               0x8CED
#define GL_COLOR_ATTACHMENT14_EXT               0x8CEE
#define GL_COLOR_ATTACHMENT15_EXT               0x8CEF
#define GL_DEPTH_ATTACHMENT_EXT                 0x8D00
#define GL_STENCIL_ATTACHMENT_EXT               0x8D20
#define GL_FRAMEBUFFER_COMPLETE_EXT                          0x8CD5
#define GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT_EXT             0x8CD6
#define GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT_EXT     0x8CD7
#define GL_FRAMEBUFFER_INCOMPLETE_DUPLICATE_ATTACHMENT_EXT   0x8CD8
#define GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS_EXT             0x8CD9
#define GL_FRAMEBUFFER_INCOMPLETE_FORMATS_EXT                0x8CDA
#define GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER_EXT            0x8CDB
#define GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER_EXT            0x8CDC
#define GL_FRAMEBUFFER_UNSUPPORTED_EXT                       0x8CDD
#define GL_FRAMEBUFFER_BINDING_EXT             0x8CA6
#define GL_RENDERBUFFER_BINDING_EXT            0x8CA7
#define GL_MAX_COLOR_ATTACHMENTS_EXT           0x8CDF
#define GL_MAX_RENDERBUFFER_SIZE_EXT           0x84E8
#define GL_INVALID_FRAMEBUFFER_OPERATION_EXT   0x0506
#endif

namespace osg
{

    class FBOExtensions
    {
    public:
        typedef void APIENTRY TglBindRenderbufferEXT(GLenum, GLuint);
        typedef void APIENTRY TglGenRenderbuffersEXT(GLsizei, GLuint *);
        typedef void APIENTRY TglRenderbufferStorageEXT(GLenum, GLenum, GLsizei, GLsizei);
        typedef void APIENTRY TglBindFramebufferEXT(GLenum, GLuint);
        typedef void APIENTRY TglGenFramebuffersEXT(GLsizei, GLuint *);
        typedef GLenum APIENTRY TglCheckFramebufferStatusEXT(GLenum);
        typedef void APIENTRY TglFramebufferTexture1DEXT(GLenum, GLenum, GLenum, GLuint, GLint);
        typedef void APIENTRY TglFramebufferTexture2DEXT(GLenum, GLenum, GLenum, GLuint, GLint);
        typedef void APIENTRY TglFramebufferTexture3DEXT(GLenum, GLenum, GLenum, GLuint, GLint, GLint);
        typedef void APIENTRY TglFramebufferRenderbufferEXT(GLenum, GLenum, GLenum, GLuint);
        typedef void APIENTRY TglGenerateMipmapEXT(GLenum);

        TglBindRenderbufferEXT *glBindRenderbufferEXT;
        TglGenRenderbuffersEXT *glGenRenderbuffersEXT;
        TglRenderbufferStorageEXT *glRenderbufferStorageEXT;
        TglBindFramebufferEXT *glBindFramebufferEXT;
        TglGenFramebuffersEXT *glGenFramebuffersEXT;
        TglCheckFramebufferStatusEXT *glCheckFramebufferStatusEXT;
        TglFramebufferTexture1DEXT *glFramebufferTexture1DEXT;
        TglFramebufferTexture2DEXT *glFramebufferTexture2DEXT;
        TglFramebufferTexture3DEXT *glFramebufferTexture3DEXT;
        TglFramebufferRenderbufferEXT *glFramebufferRenderbufferEXT;
        TglGenerateMipmapEXT *glGenerateMipmapEXT;

        static FBOExtensions *instance(unsigned contextID)
        {
            static buffered_object<FBOExtensions *> _instances;
            FBOExtensions *ext = _instances[contextID];
            if (!ext)
            {
                ext = new FBOExtensions(contextID);
                _instances[contextID] = ext;
            }
            return ext;
        }

        bool isSupported() const { return _supported; }

    protected:
        FBOExtensions(unsigned int contextID);

    private:        
        bool _supported;
    };

}

#endif