AC_DEFUN([AX_CHECK_GL],
[AC_REQUIRE([AC_PATH_X])dnl
AC_REQUIRE([ACX_PTHREAD])dnl

#
# There isn't a reliable way to know we should use the Apple OpenGL framework
# without a configure option.  A Mac OS X user may have installed an
# alternative GL implementation (e.g., Mesa), which may or may not depend on X.
#
AC_ARG_WITH([apple-opengl-framework],
            [AC_HELP_STRING([--with-apple-opengl-framework],
                            [use Apple OpenGL framework (Mac OS X only)])])
if test "X$with_apple_opengl_framework" = "Xyes"; then
  AC_DEFINE([HAVE_APPLE_OPENGL_FRAMEWORK], [1],
            [Use the Apple OpenGL framework.])
  GL_CFLAGS="-framework OpenGL"
else
  GL_CFLAGS="${PTHREAD_CFLAGS}"
  GL_LIBS="${PTHREAD_LIBS} -lm"

  #
  # Use x_includes and x_libraries if they have been set (presumably by
  # AC_PATH_X).
  #
  if test "X$no_x" != "Xyes"; then
    if test -n "$x_includes"; then
      GL_CFLAGS="-I${x_includes} ${GL_CFLAGS}"
    fi
    if test -n "$x_libraries"; then
      GL_LIBS="-L${x_libraries} -lX11 ${GL_LIBS}"
    fi
  fi

  AC_LANG_PUSH(C)

  AC_CHECK_HEADERS([windows.h])

  AC_CACHE_CHECK([for OpenGL library], [ax_cv_check_gl_libgl],
  [ax_cv_check_gl_libgl="no"
  ax_save_CPPFLAGS="${CPPFLAGS}"
  CPPFLAGS="${GL_CFLAGS} ${CPPFLAGS}"
  ax_save_LIBS="${LIBS}"
  LIBS=""
  ax_check_libs="-lopengl32 -lGL"
    for ax_lib in ${ax_check_libs}; do
    if test "X$CC" = "Xcl"; then
      ax_try_lib=`echo $ax_lib | sed -e 's/^-l//' -e 's/$/.lib/'`
    else
      ax_try_lib="${ax_lib}"
    fi
    LIBS="${ax_try_lib} ${GL_LIBS} ${ax_save_LIBS}"
    AC_TRY_LINK([
# if HAVE_WINDOWS_H && defined(_WIN32)
#   include <windows.h>
# endif
# include <GL/gl.h>
],
    [glBegin(0)],
    [ax_cv_check_gl_libgl="${ax_try_lib}"; break])
  done
  LIBS=${ax_save_LIBS}
  CPPFLAGS=${ax_save_CPPFLAGS}])

  if test "X${ax_cv_check_gl_libgl}" = "Xno"; then
    no_gl="yes"
    GL_CFLAGS=""
    GL_LIBS=""
  else
    GL_LIBS="${ax_cv_check_gl_libgl} ${GL_LIBS}"
  fi
  AC_LANG_POP(C)
fi

AC_SUBST([GL_CFLAGS])
AC_SUBST([GL_LIBS])
])dnl