# ===========================================================================
#              http://autoconf-archive.cryp.to/ax_check_gl.html
# ===========================================================================
#
# SYNOPSIS
#
#   AX_CHECK_GL
#
# DESCRIPTION
#
#   Check for an OpenGL implementation. If GL is found, the required
#   compiler and linker flags are included in the output variables
#   "GL_CFLAGS" and "GL_LIBS", respectively. If no usable GL implementation
#   is found, "no_gl" is set to "yes".
#
#   If the header "GL/gl.h" is found, "HAVE_GL_GL_H" is defined. If the
#   header "OpenGL/gl.h" is found, HAVE_OPENGL_GL_H is defined. These
#   preprocessor definitions may not be mutually exclusive.
#
# LAST MODIFICATION
#
#   2008-10-07
#
# COPYLEFT
#
#   Copyright (c) 2008 Braden McDaniel <braden@endoframe.com>
#
#   This program is free software; you can redistribute it and/or modify it
#   under the terms of the GNU General Public License as published by the
#   Free Software Foundation; either version 2 of the License, or (at your
#   option) any later version.
#
#   This program 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 GNU General
#   Public License for more details.
#
#   You should haeceived a copy of the GNU General Public License along
#   with this program. If not, see <http://www.gnu.org/licenses/>.
#
#   As a special exception, the respective Autoconf Macro's copyright owner
#   gives unlimited permission to copy, distribute and modify the configure
#   scripts that are the output of Autoconf when processing the Macro. You
#   need not follow the terms of the GNU General Public License when using
#   or distributing such scripts, even though portions of the text of the
#   Macro appear in them. The GNU General Public License (GPL) does govern
#   all other use of the material that constitutes the Autoconf Macro.
#
#   This special exception to the GPL applies to versions of the Autoconf
#   Macro released by the Autoconf Macro Archive. When you make and
#   distribute a modified version of the Autoconf Macro, you may extend this
#   special exception to the GPL to apply to your modified version as well.

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

AC_LANG_PUSH([C])
AX_LANG_COMPILER_MS
AS_IF([test X$ax_compiler_ms = Xno],
      [GL_CFLAGS="${PTHREAD_CFLAGS}"; GL_LIBS="${PTHREAD_LIBS} -lm"])

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

ax_save_CPPFLAGS="${CPPFLAGS}"
CPPFLAGS="${GL_CFLAGS} ${CPPFLAGS}"
AC_CHECK_HEADERS([GL/gl.h OpenGL/gl.h])
CPPFLAGS="${ax_save_CPPFLAGS}"

AC_CHECK_HEADERS([windows.h])

m4_define([AX_CHECK_GL_PROGRAM],
          [AC_LANG_PROGRAM([[
# if defined(HAVE_WINDOWS_H) && defined(_WIN32)
#   include <windows.h>
# endif
# ifdef HAVE_GL_GL_H
#   include <GL/gl.h>
# elif defined(HAVE_OPENGL_GL_H)
#   include <OpenGL/gl.h>
# else
#   error no gl.h
# endif]],
                           [[glBegin(0)]])])

AC_CACHE_CHECK([for OpenGL library], [ax_cv_check_gl_libgl],
[ax_cv_check_gl_libgl="no"
case $host_cpu in
  x86_64) ax_check_gl_libdir=lib64 ;;
  *)      ax_check_gl_libdir=lib ;;
esac
ax_save_CPPFLAGS="${CPPFLAGS}"
CPPFLAGS="${GL_CFLAGS} ${CPPFLAGS}"
ax_save_LIBS="${LIBS}"
LIBS=""
ax_check_libs="-lopengl32 -lGL"
for ax_lib in ${ax_check_libs}; do
  AS_IF([test X$ax_compiler_ms = Xyes],
        [ax_try_lib=`echo $ax_lib | sed -e 's/^-l//' -e 's/$/.lib/'`],
        [ax_try_lib="${ax_lib}"])
  LIBS="${ax_try_lib} ${GL_LIBS} ${ax_save_LIBS}"
AC_LINK_IFELSE([AX_CHECK_GL_PROGRAM],
               [ax_cv_check_gl_libgl="${ax_try_lib}"; break],
               [ax_check_gl_nvidia_flags="-L/usr/${ax_check_gl_libdir}/nvidia" LIBS="${ax_try_lib} ${ax_check_gl_nvidia_flags} ${GL_LIBS} ${ax_save_LIBS}"
AC_LINK_IFELSE([AX_CHECK_GL_PROGRAM],
               [ax_cv_check_gl_libgl="${ax_try_lib} ${ax_check_gl_nvidia_flags}"; break],
               [ax_check_gl_dylib_flag='-dylib_file /System/Library/Frameworks/OpenGL.framework/Versions/A/Libraries/libGL.dylib:/System/Library/Frameworks/OpenGL.framework/Versions/A/Libraries/libGL.dylib' LIBS="${ax_try_lib} ${ax_check_gl_dylib_flag} ${GL_LIBS} ${ax_save_LIBS}"
AC_LINK_IFELSE([AX_CHECK_GL_PROGRAM],
               [ax_cv_check_gl_libgl="${ax_try_lib} ${ax_check_gl_dylib_flag}"; break])])])
done

AS_IF([test "X$ax_cv_check_gl_libgl" = Xno -a "X$no_x" = Xyes],
[LIBS='-framework OpenGL'
AC_LINK_IFELSE([AX_CHECK_GL_PROGRAM],
               [ax_cv_check_gl_libgl="$LIBS"])])

LIBS=${ax_save_LIBS}
CPPFLAGS=${ax_save_CPPFLAGS}])

AS_IF([test "X$ax_cv_check_gl_libgl" = Xno],
      [no_gl=yes; GL_CFLAGS=""; GL_LIBS=""],
      [GL_LIBS="${ax_cv_check_gl_libgl} ${GL_LIBS}"])
AC_LANG_POP([C])

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