#ifndef OSG_GL
#define OSG_GL 1

#ifdef WIN32

	// this works with no problems
//    #ifndef _WINDOWS_
//		#define  WIN32_LEAN_AND_MEAN
//        #include <windows.h>
//    #endif

// follows lifted from glut.h, to avoid including <windows.h>

//#if defined(_WIN32)

// GLUT 3.7 now tries to avoid including <windows.h>
//   to avoid name space pollution, but Win32's <GL/gl.h> 
//   needs APIENTRY and WINGDIAPI defined properly. 
# if 0
#  define  WIN32_LEAN_AND_MEAN
#  include <windows.h>
# else
   // XXX This is from Win32's <windef.h> 
#  ifndef APIENTRY
#   define GLUT_APIENTRY_DEFINED
#   if (_MSC_VER >= 800) || defined(_STDCALL_SUPPORTED)
#    define APIENTRY    __stdcall
#   else
#    define APIENTRY
#   endif
#  endif
   // XXX This is from Win32's <winnt.h> 
#  ifndef CALLBACK
#   if (defined(_M_MRX000) || defined(_M_IX86) || defined(_M_ALPHA) || defined(_M_PPC)) && !defined(MIDL_PASS)
#    define CALLBACK __stdcall
#   else
#    define CALLBACK
#   endif
#  endif
   // XXX This is from Win32's <wingdi.h> and <winnt.h> 
#  ifndef WINGDIAPI
#   define GLUT_WINGDIAPI_DEFINED
#   define WINGDIAPI __declspec(dllimport)
#  endif
   // XXX This is from Win32's <ctype.h> 
#  ifndef _WCHAR_T_DEFINED
typedef unsigned short wchar_t;
#   define _WCHAR_T_DEFINED
#  endif
# endif



    #ifndef __gl_h_
        #include <GL/gl.h>
    #endif
    #ifndef __glu_h__
        #include <GL/glu.h>
    #endif
  
#else

    // GL_GLEXT_LEGACY required by some Linux OpenGL implementations
    // to allow compilation of glPointParameterfEXT.
    #define GL_GLEXT_LEGACY 1
    #include <GL/gl.h>
    #include <GL/glu.h>
    #include <GL/glx.h>
#endif

#endif  // __osgGL_h