# ===========================================================================
#         http://www.nongnu.org/autoconf-archive/mdl_have_opengl.html
# ===========================================================================
#
# SYNOPSIS
#
#   MDL_HAVE_OPENGL
#
# DESCRIPTION
#
#   Search for OpenGL. We search first for Mesa (a GPL'ed version of Mesa)
#   before a vendor's version of OpenGL, unless we were specifically asked
#   not to with `--with-Mesa=no' or `--without-Mesa'.
#
#   The four "standard" OpenGL libraries are searched for: "-lGL", "-lGLU",
#   "-lGLX" (or "-lMesaGL", "-lMesaGLU" as the case may be) and "-lglut".
#
#   All of the libraries that are found (since "-lglut" or "-lGLX" might be
#   missing) are added to the shell output variable "GL_LIBS", along with
#   any other libraries that are necessary to successfully link an OpenGL
#   application (e.g. the X11 libraries). Care has been taken to make sure
#   that all of the libraries in "GL_LIBS" are listed in the proper order.
#
#   Additionally, the shell output variable "GL_CFLAGS" is set to any flags
#   (e.g. "-I" flags) that are necessary to successfully compile an OpenGL
#   application.
#
#   The following shell variable (which are not output variables) are also
#   set to either "yes" or "no" (depending on which libraries were found) to
#   help you determine exactly what was found.
#
#     have_GL
#     have_GLU
#     have_GLX
#     have_glut
#
# LICENSE
#
#   Copyright (c) 2008 Matthew D. Langston
#   Copyright (c) 2008 Ahmet Inan <auto@ainan.org>
#
#   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 have received 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 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([MDL_HAVE_OPENGL],
[
  AC_REQUIRE([AC_PROG_CC])
  AC_REQUIRE([AC_PATH_X])
  AC_REQUIRE([AC_PATH_XTRA])

  AC_CACHE_CHECK([for OpenGL], mdl_cv_have_OpenGL,
  [
dnl Check for Mesa first, unless we were asked not to.
    AC_ARG_WITH([--with-Mesa],
                   [Prefer the Mesa library over a vendors native OpenGL library (default=yes)],
                   with_Mesa_help_string)
    AC_ARG_ENABLE(Mesa, $with_Mesa_help_string, use_Mesa=$enableval, use_Mesa=yes)

    if test x"$use_Mesa" = xyes; then
       GL_search_list="MesaGL   GL"
      GLU_search_list="MesaGLU GLU"
      GLX_search_list="MesaGLX GLX"
    else
       GL_search_list="GL  MesaGL"
      GLU_search_list="GLU MesaGLU"
      GLX_search_list="GLX MesaGLX"
    fi

    AC_LANG_SAVE
    AC_LANG_C

dnl If we are running under X11 then add in the appropriate libraries.
if test x"$no_x" != xyes; then
dnl Add everything we need to compile and link X programs to GL_X_CFLAGS
dnl and GL_X_LIBS.
  GL_CFLAGS="$X_CFLAGS"
  GL_X_LIBS="$X_PRE_LIBS $X_LIBS -lX11 -lXext -lXmu -lXt -lXi $X_EXTRA_LIBS"
fi
    GL_save_CPPFLAGS="$CPPFLAGS"
    CPPFLAGS="$GL_CFLAGS"

    GL_save_LIBS="$LIBS"
    LIBS="$GL_X_LIBS"


    # Save the "AC_MSG_RESULT file descriptor" to FD 8.
    exec 8>&AC_FD_MSG

    # Temporarily turn off AC_MSG_RESULT so that the user gets pretty
    # messages.
    exec AC_FD_MSG>/dev/null

    AC_SEARCH_LIBS(glAccum,          $GL_search_list, have_GL=yes,   have_GL=no)
    AC_SEARCH_LIBS(gluBeginCurve,   $GLU_search_list, have_GLU=yes,  have_GLU=no)
    AC_SEARCH_LIBS(glXChooseVisual, $GLX_search_list, have_GLX=yes,  have_GLX=no)
    AC_SEARCH_LIBS(glutInit,        glut,             have_glut=yes, have_glut=no)



    # Restore pretty messages.
    exec AC_FD_MSG>&8

    if test -n "$LIBS"; then
      mdl_cv_have_OpenGL=yes
      GL_LIBS="$LIBS"
      AC_SUBST(GL_CFLAGS)
      AC_SUBST(GL_LIBS)
    else
      mdl_cv_have_OpenGL=no
      GL_CFLAGS=
    fi

dnl Reset GL_X_LIBS regardless, since it was just a temporary variable
dnl and we don't want to be global namespace polluters.
    GL_X_LIBS=

    LIBS="$GL_save_LIBS"
    CPPFLAGS="$GL_save_CPPFLAGS"

    AC_LANG_RESTORE

dnl bugfix: dont forget to cache this variables, too
    mdl_cv_GL_CFLAGS="$GL_CFLAGS"
    mdl_cv_GL_LIBS="$GL_LIBS"
    mdl_cv_have_GL="$have_GL"
    mdl_cv_have_GLU="$have_GLU"
    mdl_cv_have_GLX="$have_GLX"
    mdl_cv_have_glut="$have_glut"
  ])
  GL_CFLAGS="$mdl_cv_GL_CFLAGS"
  GL_LIBS="$mdl_cv_GL_LIBS"
  have_GL="$mdl_cv_have_GL"
  have_GLU="$mdl_cv_have_GLU"
  have_GLX="$mdl_cv_have_GLX"
  have_glut="$mdl_cv_have_glut"
])
dnl endof bugfix -ainan