documentation/opengl.sgml - wine - Git at Google

   <chapter id="opengl">
     <title>Wine and OpenGL</title>

     <sect1 id="opengl-required">
       <title>What is needed to have OpenGL support in Wine</title>

       <para>
         Basically, if you have a Linux OpenGL ABI compliant libGL
         (<ulink url="http://oss.sgi.com/projects/ogl-sample/ABI/">
           http://oss.sgi.com/projects/ogl-sample/ABI/</ulink>)
         installed on your computer, you should have everything
 	that is needed.
       </para>
       <para>
         To be more clear, I will detail one step after another what
         the <command>configure</command> script checks.
       </para>
       <para>
         If, after Wine compiles, OpenGL support is not compiled in,
         you can always check <filename>config.log</filename> to see
         which of the following points failed.
       </para>

       <sect2>
         <title>Header files</title>

         <para>
           The needed header files to build OpenGL support in Wine are :
         </para>

         <variablelist>
           <varlistentry>
             <term><filename>gl.h:</filename></term>
             <listitem>
               <para>
                 the definition of all OpenGL core functions, types and enumerants
               </para>
             </listitem>
           </varlistentry>
           <varlistentry>
             <term><filename>glx.h:</filename></term>
             <listitem>
               <para>
                 how OpenGL integrates in the X Window environment
               </para>
             </listitem>
           </varlistentry>
           <varlistentry>
             <term><filename>glext.h:</filename></term>
             <listitem>
               <para>
                 the list of all registered OpenGL extensions
               </para>
             </listitem>
           </varlistentry>
         </variablelist>

         <para>
           The latter file (<filename>glext.h</filename>) is, as of
           now, not necessary to build Wine. But as this file can be
           easily obtained from SGI
           (<ulink url="http://oss.sgi.com/projects/ogl-sample/ABI/glext.h">
             http://oss.sgi.com/projects/ogl-sample/ABI/glext.h</ulink>),
           and that all OpenGL should provide one, I decided to keep it here.
         </para>
       </sect2>

       <sect2>
         <title>OpenGL library thread-safety</title>

         <para>
           After that, the script checks if the OpenGL library relies
           or not on the pthread library to provide thread safety (most
           'modern' OpenGL libraries do).
         </para>
         <para>
           If the OpenGL library explicitly links in libpthread (you
           can check it with a <command>ldd libGL.so</command>), you
           need to force OpenGL support by starting
           <command>configure</command> with the
           <parameter>--enable-opengl</parameter> flag.
         </para>
         <para>
           The reason to this is that Wine contains some hacks done by
           Ove to cohabit with pthread that are known to work well in
           most of the cases (glibc 2.1.x). On the other hand, we never
           got Wine to work with glibc 2.0.6. Thus, I deemed preferable
           to play it safe : by default, I suppose that the hack won't
           work and that it's the user's responsibility to enable it.
         </para>
         <para>
           Anyway, it should be pretty safe to build with
           <parameter>--enable-opengl</parameter>.
         </para>
       </sect2>

       <sect2>
         <title>OpenGL library itself</title>

         <para>
           To check for the presence of 'libGL' on the system, the
           script checks if it defines the
           <function>glXCreateContext</function> function. There should
           be no problem here.
         </para>
       </sect2>

       <sect2>
         <title>glXGetProcAddressARB function</title>

         <para>
           The core of Wine's OpenGL implementation (at least for all
           extensions) is the <function>glXGetProcAddressARB</function>
           function. Your OpenGL library needs to have this function
           defined for Wine to be able to support OpenGL.
         </para>
         <para>
           If your library does not provide it, you are out of luck.
         </para>
         <note>
           <para>
             this is not completely true as one could rewrite a
             <function>glXGetProcAddressARB</function> replacement
             using <function>dlopen</function> and friends, but well,
             telling people to upgrade is easier :-).
           </para>
         </note>
       </sect2>
     </sect1>

     <sect1 id="opengl-configure">
       <title>How to configure</title>

       <para>
         Configuration is quite easy : once OpenGL support has been
         built in Wine, this internal OpenGL driver will be used each
         time an application tries to load
         <filename>opengl32.dll</filename>.
       </para>
       <para>
         Due to restrictions (that do not exist in Windows) on OpenGL
         contexts, if you want to prevent the screen to flicker when
         using OpenGL applications (all games are using double-buffered
         contexts), you need to set the following option in your
         <filename>~/.wine/config</filename> file
         in the [x11drv] section :
       </para>
       <programlisting>
 DesktopDoubleBuffered = Y
       </programlisting>
       <para>
         and to run Wine with the <parameter>--desktop</parameter>
         option.
       </para>
     </sect1>

     <sect1 id="opengl-works">
       <title>How it all works</title>

       <para>
         The core OpenGL function calls are the same between Windows
         and Linux. So what is the difficulty to support it in Wine ?
         Well, there are two different problems :
       </para>

       <orderedlist>
         <listitem>
           <para>
             the interface to the windowing system is different for
             each OS. It's called 'GLX' for Linux (well, for X Window)
             and 'wgl' for Windows. Thus, one need first to emulate one
             (wgl) with the other (GLX).
           </para>
         </listitem>
         <listitem>
           <para>
             the calling convention between Windows (the 'Pascal'
             convention or 'stdcall') is different from the one used on
             Linux (the 'C' convention or 'cdecl'). This means that
             each call to an OpenGL function must be 'translated' and
             cannot be used directly by the Windows program.
           </para>
         </listitem>
       </orderedlist>

       <para>
         Add to this some brain-dead programs (using GL calls without
         setting-up a context or deleting three time the same context)
         and you have still some work to do :-)
       </para>

       <sect2>
         <title>The Windowing system integration</title>

         <para>
           This integration is done at two levels :
         </para>

         <orderedlist>
           <listitem>
             <para>
               At GDI level for all pixel format selection routines (ie
               choosing if one wants a depth / alpha buffer, the size
               of these buffers, ...) and to do the 'page flipping' in
               double buffer mode. This is implemented in
               <filename>graphics/x11drv/opengl.c</filename> (all these
               functions are part of Wine's graphic driver function
               pointer table and thus could be reimplemented if ever Wine
               works on another Windowing system than X).
             </para>
           </listitem>
           <listitem>
             <para>
               In the <filename>OpenGL32.DLL</filename> itself for all
               other functionalities (context creation / deletion,
               querying of extension functions, ...). This is done in
               <filename>dlls/opengl32/wgl.c</filename>.
             </para>
           </listitem>
         </orderedlist>
       </sect2>

       <sect2>
         <title>The thunks</title>

         <para>
           The thunks are the Wine code that does the calling
           convention translation and they are auto-generated by a Perl
           script. In Wine's CVS tree, these thunks are already
           generated for you. Now, if you want to do it yourself, there
           is how it all works....
         </para>
         <para>
           The script is located in <filename>dlls/opengl32</filename>
           and is called <command>make_opengl</command>. It requires
           Perl5 to work and takes two arguments :
         </para>

         <orderedlist>
           <listitem>
             <para>
               The first is the path to the OpenGL registry. Now, you
               will all ask 'but what is the OpenGL registry ?' :-)
               Well, it's part of the OpenGL sample implementation
               source tree from SGI (more informations at this URL :
               <ulink url="http://oss.sgi.com/projects/ogl-sample/">
                 http://oss.sgi.com/projects/ogl-sample/</ulink>.
             </para>
             <para>
               To summarize, these files contain human-readable but
               easily parsed information on ALL OpenGL core functions
               and ALL registered extensions (for example the
               prototype, the OpenGL version, ...).
             </para>
           </listitem>
           <listitem>
             <para>
               the second is the OpenGL version to 'simulate'. This
               fixes the list of functions that the Windows application
               can link directly to without having to query them from
               the OpenGL driver. Windows is based, for now, on OpenGL
               1.1, but the thunks that are in the CVS tree are
               generated for OpenGL 1.2.
             </para>
             <para>
               This option can have three values:
               <literal>1.0</literal>, <literal>1.1</literal> and
               <literal>1.2</literal>.
             </para>
           </listitem>
         </orderedlist>

         <para>
           This script generates three files :
         </para>

         <orderedlist>
           <listitem>
             <para>
               <filename>opengl32.spec</filename> gives Wine's linker
               the signature of all function in the
               <filename>OpenGL32.DLL</filename> library so that the
               application can link them. Only 'core' functions are
               listed here.
             </para>
           </listitem>
           <listitem>
             <para>
               <filename>opengl_norm.c</filename> contains all the
               thunks for the 'core' functions. Your OpenGL library
               must provide ALL the function used in this file as these
               are not queried at run time.
             </para>
           </listitem>
           <listitem>
             <para>
               <filename>opengl_ext.c</filename> contains all the
               functions that are not part of the 'core' functions.
               Contrary to the thunks in
               <filename>opengl_norm.c</filename>, these functions do
               not depend at all on what your libGL provides.
             </para>
             <para>
               In fact, before using one of these thunks, the Windows
               program first needs to 'query' the function pointer. At
               this point, the corresponding thunk is useless. But as
               we first query the same function in libGL and store the
               returned function pointer in the thunk, the latter
               becomes functional.
             </para>
           </listitem>
         </orderedlist>
       </sect2>
     </sect1>

     <sect1 id="opengl-problems">
       <title>Known problems - shortcomings</title>

       <sect2>
         <title>Missing GLU32.DLL</title>

         <para>
           GLU is a library that is layered upon OpenGL. There is a
           100% correspondence between the
           <filename>libGLU.so</filename> that is used on Linux and
           <filename>GLU32.DLL</filename>.
         </para>
         <para>
           As for the moment, I did not create a set of thunks to support this
           library natively in Wine (it would easy to do, but I am waiting for
           a better solution than adding another autogenerated thunk file), you
           can always download anywhere on the net (it's free) a
           <filename>GLU32.DLL</filename> file (by browsing, for example,
           <ulink url="http://www.dll-files.com/dllindex/index.shtml">
             http://www.dll-files.com/dllindex/index.shtml</ulink>).
         </para>
       </sect2>

       <sect2>
         <title>OpenGL not detected at configure time</title>

         <para>
           See section (I) for a detailed explanation of the
           <filename>configure</filename> requirements.
         </para>
       </sect2>

       <sect2>
         <title>When running an OpenGL application, the screen flickers</title>

         <para>
           See section (II) for how to create the context
           double-buffered and thus preventing this flicker effect.
         </para>
       </sect2>

       <sect2>
         <title>Wine gives me the following error message : </title>

         <screen>
 Extension defined in the OpenGL library but NOT in opengl_ext.c...
 Please report (lionel.ulmer@free.fr) !
         </screen>

         <para>
           This means that the extension requested by the application
           is found in the libGL used by Linux (ie the call to
           <function>glXGetProcAddressARB</function> returns a
           non-<constant>NULL</constant> pointer) but that this string
           was NOT found in Wine's extension registry.
         </para>
         <para>
           This can come from two causes :
         </para>

         <orderedlist>
           <listitem>
             <para>
               The <filename>opengl_ext.c</filename> file is too old
               and needs to be generated again.
             </para>
           </listitem>
           <listitem>
             <para>
               Use of obsolete extensions that are not supported
               anymore by SGI or of 'private' extensions that are not
               registered. An example of the former are
               <function>glMTexCoord2fSGIS</function> and
               <function>glSelectTextureSGIS</function> as used by
               Quake 2 (and apparently also by old versions of Half
               Life). If documentation can be found on these functions,
               they can be added to Wine's extension set.
             </para>
           </listitem>
         </orderedlist>

         <para>
           If you have this, run with <parameter>--debugmsg
             +opengl</parameter> and send me
           <email>lionel.ulmer@free.fr</email> the TRACE.
         </para>
       </sect2>

       <sect2>
         <title><filename>libopengl32.so</filename> is built but it is still not working</title>

         <para>
           This may be caused by some missing functions required by
           <filename>opengl_norm.c</filename> but that your Linux
           OpenGL library does not provide.
         </para>
         <para>
           To check for this, do the following steps :
         </para>

         <orderedlist>
           <listitem>
             <para>
               create a dummy <filename>.c</filename> file :
             </para>
             <programlisting>
 int main(void) {
     return 0;
 }
             </programlisting>
           </listitem>
           <listitem>
             <para>
               try to compile it by linking both libwine and
               libopengl32 (this command line supposes that you
               installed the Wine libraries in
               <filename>/usr/local/lib</filename>, YMMV) :
             </para>
             <programlisting>
 gcc dummy.c -L/usr/local/lib -lwine -lopengl32
             </programlisting>
           </listitem>
           <listitem>
             <para>
               if it works, the problem is somewhere else (and you can
               send me an email). If not, you could re-generate the
               thunk files for OpenGL 1.1 for example (and send me your
               OpenGL version so that this problem can be detected at
               configure time).
             </para>
           </listitem>
         </orderedlist>
       </sect2>
     </sect1>
   </chapter>

 <!-- Keep this comment at the end of the file
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	<chapter id="opengl">
	<title>Wine and OpenGL</title>

	<sect1 id="opengl-required">
	<title>What is needed to have OpenGL support in Wine</title>

	<para>
	Basically, if you have a Linux OpenGL ABI compliant libGL
	(<ulink url="http://oss.sgi.com/projects/ogl-sample/ABI/">
	http://oss.sgi.com/projects/ogl-sample/ABI/</ulink>)
	installed on your computer, you should have everything
	that is needed.
	</para>
	<para>
	To be more clear, I will detail one step after another what
	the <command>configure</command> script checks.
	</para>
	<para>
	If, after Wine compiles, OpenGL support is not compiled in,
	you can always check <filename>config.log</filename> to see
	which of the following points failed.
	</para>

	<sect2>
	<title>Header files</title>

	<para>
	The needed header files to build OpenGL support in Wine are :
	</para>

	<variablelist>
	<varlistentry>
	<term><filename>gl.h:</filename></term>
	<listitem>
	<para>
	the definition of all OpenGL core functions, types and enumerants
	</para>
	</listitem>
	</varlistentry>
	<varlistentry>
	<term><filename>glx.h:</filename></term>
	<listitem>
	<para>
	how OpenGL integrates in the X Window environment
	</para>
	</listitem>
	</varlistentry>
	<varlistentry>
	<term><filename>glext.h:</filename></term>
	<listitem>
	<para>
	the list of all registered OpenGL extensions
	</para>
	</listitem>
	</varlistentry>
	</variablelist>

	<para>
	The latter file (<filename>glext.h</filename>) is, as of
	now, not necessary to build Wine. But as this file can be
	easily obtained from SGI
	(<ulink url="http://oss.sgi.com/projects/ogl-sample/ABI/glext.h">
	http://oss.sgi.com/projects/ogl-sample/ABI/glext.h</ulink>),
	and that all OpenGL should provide one, I decided to keep it here.
	</para>
	</sect2>

	<sect2>
	<title>OpenGL library thread-safety</title>

	<para>
	After that, the script checks if the OpenGL library relies
	or not on the pthread library to provide thread safety (most
	'modern' OpenGL libraries do).
	</para>
	<para>
	If the OpenGL library explicitly links in libpthread (you
	can check it with a <command>ldd libGL.so</command>), you
	need to force OpenGL support by starting
	<command>configure</command> with the
	<parameter>--enable-opengl</parameter> flag.
	</para>
	<para>
	The reason to this is that Wine contains some hacks done by
	Ove to cohabit with pthread that are known to work well in
	most of the cases (glibc 2.1.x). On the other hand, we never
	got Wine to work with glibc 2.0.6. Thus, I deemed preferable
	to play it safe : by default, I suppose that the hack won't
	work and that it's the user's responsibility to enable it.
	</para>
	<para>
	Anyway, it should be pretty safe to build with
	<parameter>--enable-opengl</parameter>.
	</para>
	</sect2>

	<sect2>
	<title>OpenGL library itself</title>

	<para>
	To check for the presence of 'libGL' on the system, the
	script checks if it defines the
	<function>glXCreateContext</function> function. There should
	be no problem here.
	</para>
	</sect2>

	<sect2>
	<title>glXGetProcAddressARB function</title>

	<para>
	The core of Wine's OpenGL implementation (at least for all
	extensions) is the <function>glXGetProcAddressARB</function>
	function. Your OpenGL library needs to have this function
	defined for Wine to be able to support OpenGL.
	</para>
	<para>
	If your library does not provide it, you are out of luck.
	</para>
	<note>
	<para>
	this is not completely true as one could rewrite a
	<function>glXGetProcAddressARB</function> replacement
	using <function>dlopen</function> and friends, but well,
	telling people to upgrade is easier :-).
	</para>
	</note>
	</sect2>
	</sect1>

	<sect1 id="opengl-configure">
	<title>How to configure</title>

	<para>
	Configuration is quite easy : once OpenGL support has been
	built in Wine, this internal OpenGL driver will be used each
	time an application tries to load
	<filename>opengl32.dll</filename>.
	</para>
	<para>
	Due to restrictions (that do not exist in Windows) on OpenGL
	contexts, if you want to prevent the screen to flicker when
	using OpenGL applications (all games are using double-buffered
	contexts), you need to set the following option in your
	<filename>~/.wine/config</filename> file
	in the [x11drv] section :
	</para>
	<programlisting>
	DesktopDoubleBuffered = Y
	</programlisting>
	<para>
	and to run Wine with the <parameter>--desktop</parameter>
	option.
	</para>
	</sect1>

	<sect1 id="opengl-works">
	<title>How it all works</title>

	<para>
	The core OpenGL function calls are the same between Windows
	and Linux. So what is the difficulty to support it in Wine ?
	Well, there are two different problems :
	</para>

	<orderedlist>
	<listitem>
	<para>
	the interface to the windowing system is different for
	each OS. It's called 'GLX' for Linux (well, for X Window)
	and 'wgl' for Windows. Thus, one need first to emulate one
	(wgl) with the other (GLX).
	</para>
	</listitem>
	<listitem>
	<para>
	the calling convention between Windows (the 'Pascal'
	convention or 'stdcall') is different from the one used on
	Linux (the 'C' convention or 'cdecl'). This means that
	each call to an OpenGL function must be 'translated' and
	cannot be used directly by the Windows program.
	</para>
	</listitem>
	</orderedlist>

	<para>
	Add to this some brain-dead programs (using GL calls without
	setting-up a context or deleting three time the same context)
	and you have still some work to do :-)
	</para>

	<sect2>
	<title>The Windowing system integration</title>

	<para>
	This integration is done at two levels :
	</para>

	<orderedlist>
	<listitem>
	<para>
	At GDI level for all pixel format selection routines (ie
	choosing if one wants a depth / alpha buffer, the size
	of these buffers, ...) and to do the 'page flipping' in
	double buffer mode. This is implemented in
	<filename>graphics/x11drv/opengl.c</filename> (all these
	functions are part of Wine's graphic driver function
	pointer table and thus could be reimplemented if ever Wine
	works on another Windowing system than X).
	</para>
	</listitem>
	<listitem>
	<para>
	In the <filename>OpenGL32.DLL</filename> itself for all
	other functionalities (context creation / deletion,
	querying of extension functions, ...). This is done in
	<filename>dlls/opengl32/wgl.c</filename>.
	</para>
	</listitem>
	</orderedlist>
	</sect2>

	<sect2>
	<title>The thunks</title>

	<para>
	The thunks are the Wine code that does the calling
	convention translation and they are auto-generated by a Perl
	script. In Wine's CVS tree, these thunks are already
	generated for you. Now, if you want to do it yourself, there
	is how it all works....
	</para>
	<para>
	The script is located in <filename>dlls/opengl32</filename>
	and is called <command>make_opengl</command>. It requires
	Perl5 to work and takes two arguments :
	</para>

	<orderedlist>
	<listitem>
	<para>
	The first is the path to the OpenGL registry. Now, you
	will all ask 'but what is the OpenGL registry ?' :-)
	Well, it's part of the OpenGL sample implementation
	source tree from SGI (more informations at this URL :
	<ulink url="http://oss.sgi.com/projects/ogl-sample/">
	http://oss.sgi.com/projects/ogl-sample/</ulink>.
	</para>
	<para>
	To summarize, these files contain human-readable but
	easily parsed information on ALL OpenGL core functions
	and ALL registered extensions (for example the
	prototype, the OpenGL version, ...).
	</para>
	</listitem>
	<listitem>
	<para>
	the second is the OpenGL version to 'simulate'. This
	fixes the list of functions that the Windows application
	can link directly to without having to query them from
	the OpenGL driver. Windows is based, for now, on OpenGL
	1.1, but the thunks that are in the CVS tree are
	generated for OpenGL 1.2.
	</para>
	<para>
	This option can have three values:
	<literal>1.0</literal>, <literal>1.1</literal> and
	<literal>1.2</literal>.
	</para>
	</listitem>
	</orderedlist>

	<para>
	This script generates three files :
	</para>

	<orderedlist>
	<listitem>
	<para>
	<filename>opengl32.spec</filename> gives Wine's linker
	the signature of all function in the
	<filename>OpenGL32.DLL</filename> library so that the
	application can link them. Only 'core' functions are
	listed here.
	</para>
	</listitem>
	<listitem>
	<para>
	<filename>opengl_norm.c</filename> contains all the
	thunks for the 'core' functions. Your OpenGL library
	must provide ALL the function used in this file as these
	are not queried at run time.
	</para>
	</listitem>
	<listitem>
	<para>
	<filename>opengl_ext.c</filename> contains all the
	functions that are not part of the 'core' functions.
	Contrary to the thunks in
	<filename>opengl_norm.c</filename>, these functions do
	not depend at all on what your libGL provides.
	</para>
	<para>
	In fact, before using one of these thunks, the Windows
	program first needs to 'query' the function pointer. At
	this point, the corresponding thunk is useless. But as
	we first query the same function in libGL and store the
	returned function pointer in the thunk, the latter
	becomes functional.
	</para>
	</listitem>
	</orderedlist>
	</sect2>
	</sect1>

	<sect1 id="opengl-problems">
	<title>Known problems - shortcomings</title>

	<sect2>
	<title>Missing GLU32.DLL</title>

	<para>
	GLU is a library that is layered upon OpenGL. There is a
	100% correspondence between the
	<filename>libGLU.so</filename> that is used on Linux and
	<filename>GLU32.DLL</filename>.
	</para>
	<para>
	As for the moment, I did not create a set of thunks to support this
	library natively in Wine (it would easy to do, but I am waiting for
	a better solution than adding another autogenerated thunk file), you
	can always download anywhere on the net (it's free) a
	<filename>GLU32.DLL</filename> file (by browsing, for example,
	<ulink url="http://www.dll-files.com/dllindex/index.shtml">
	http://www.dll-files.com/dllindex/index.shtml</ulink>).
	</para>
	</sect2>

	<sect2>
	<title>OpenGL not detected at configure time</title>

	<para>
	See section (I) for a detailed explanation of the
	<filename>configure</filename> requirements.
	</para>
	</sect2>

	<sect2>
	<title>When running an OpenGL application, the screen flickers</title>

	<para>
	See section (II) for how to create the context
	double-buffered and thus preventing this flicker effect.
	</para>
	</sect2>

	<sect2>
	<title>Wine gives me the following error message : </title>

	<screen>
	Extension defined in the OpenGL library but NOT in opengl_ext.c...
	Please report (lionel.ulmer@free.fr) !
	</screen>

	<para>
	This means that the extension requested by the application
	is found in the libGL used by Linux (ie the call to
	<function>glXGetProcAddressARB</function> returns a
	non-<constant>NULL</constant> pointer) but that this string
	was NOT found in Wine's extension registry.
	</para>
	<para>
	This can come from two causes :
	</para>

	<orderedlist>
	<listitem>
	<para>
	The <filename>opengl_ext.c</filename> file is too old
	and needs to be generated again.
	</para>
	</listitem>
	<listitem>
	<para>
	Use of obsolete extensions that are not supported
	anymore by SGI or of 'private' extensions that are not
	registered. An example of the former are
	<function>glMTexCoord2fSGIS</function> and
	<function>glSelectTextureSGIS</function> as used by
	Quake 2 (and apparently also by old versions of Half
	Life). If documentation can be found on these functions,
	they can be added to Wine's extension set.
	</para>
	</listitem>
	</orderedlist>

	<para>
	If you have this, run with <parameter>--debugmsg
	+opengl</parameter> and send me
	<email>lionel.ulmer@free.fr</email> the TRACE.
	</para>
	</sect2>

	<sect2>
	<title><filename>libopengl32.so</filename> is built but it is still not working</title>

	<para>
	This may be caused by some missing functions required by
	<filename>opengl_norm.c</filename> but that your Linux
	OpenGL library does not provide.
	</para>
	<para>
	To check for this, do the following steps :
	</para>

	<orderedlist>
	<listitem>
	<para>
	create a dummy <filename>.c</filename> file :
	</para>
	<programlisting>
	int main(void) {
	return 0;
	}
	</programlisting>
	</listitem>
	<listitem>
	<para>
	try to compile it by linking both libwine and
	libopengl32 (this command line supposes that you
	installed the Wine libraries in
	<filename>/usr/local/lib</filename>, YMMV) :
	</para>
	<programlisting>
	gcc dummy.c -L/usr/local/lib -lwine -lopengl32
	</programlisting>
	</listitem>
	<listitem>
	<para>
	if it works, the problem is somewhere else (and you can
	send me an email). If not, you could re-generate the
	thunk files for OpenGL 1.1 for example (and send me your
	OpenGL version so that this problem can be detected at
	configure time).
	</para>
	</listitem>
	</orderedlist>
	</sect2>
	</sect1>
	</chapter>

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