3 <head><title>Mesa FAQ
</title></head>
5 <BODY text=
"#000000" bgcolor=
"#55bbff" link=
"#111188">
9 <h1>Mesa Frequently Asked Questions
</h1>
10 Last updated:
27 April
2004
16 <a href=
"#part1">1. High-level Questions and Answers
</a>
18 <a href=
"#part2">2. Compilation and Installation Problems
</a>
20 <a href=
"#part3">3. Runtime / Rendering Problems
</a>
22 <a href=
"#part4">4. Developer Questions
</a>
30 </a><h1><a name=
"part1">1. High-level Questions and Answers
</a></h1>
32 <h2><a name=
"part1">1.1 What is Mesa?
</a></h2>
34 <a name=
"part1">Mesa is an open-source implementation of the OpenGL specification.
35 OpenGL is a programming library for writing interactive
3D applications.
36 See the
</a><a href=
"http://www.opengl.org/">OpenGL website
</a> for more
40 Mesa
5.x supports the OpenGL
1.4 specification.
44 <h2>1.2 Does Mesa support/use graphics hardware?
</h2>
46 Yes. Specifically, Mesa serves as the OpenGL core for the open-source
47 XFree86/DRI OpenGL drivers. See the
<a href=
"http://dri.sf.net/">DRI
48 website
</a> for more information.
51 There have been other hardware drivers for Mesa over the years (such as
52 the
3Dfx Glide/Voodoo driver, an old S3 driver, etc) but the DRI drivers
56 <h2>1.3 What purpose does Mesa (software-based rendering) serve today?
</h2>
58 Hardware-accelerated OpenGL implementations are available for most popular
59 operating systems today.
60 Still, Mesa serves at least these purposes:
63 <li>Mesa is used as the core of the open-source XFree86/DRI hardware drivers.
65 <li>Mesa is quite portable and allows OpenGL to be used on systems
66 that have no other OpenGL solution.
68 <li>Software rendering with Mesa serves as a reference for validating the
71 <li>A software implementation of OpenGL is useful for experimentation,
72 such as testing new rendering techniques.
74 <li>Mesa can render images with deep color channels:
16-bit integer
75 and
32-bit floating point color channels are supported.
76 This capability is only now appearing in hardware.
78 <li>Mesa's internal limits (max lights, clip planes, texture size, etc) can be
79 changed for special needs (hardware limits are hard to overcome).
83 <h2>1.4 How do I upgrade my DRI installation to use a new Mesa release?
</h2>
85 You don't! A copy of the Mesa source code lives inside the XFree86/DRI source
86 tree and gets compiled into the individual DRI driver modules.
87 If you try to install Mesa over an XFree86/DRI installation, you'll lose
88 hardware rendering (because stand-alone Mesa's libGL.so is different than
89 the XFree86 libGL.so).
92 The DRI developers will incorporate the latest release of Mesa into the
93 DRI drivers when the time is right.
96 To upgrade, either look for a new release of
<a href=
"http://www.xfree86.org"
97 target=
"_parent">XFree86
</a> or visit the
98 <a href=
"http://dri.sf.net" target=
"_parent">DRI website
</a> to see
99 if there's newer drivers.
103 <h2>1.5 Are there other open-source implementations of OpenGL?
</h2>
105 Yes, SGI's
<a href=
"http://oss.sgi.com/projects/ogl-sample/index.html"
107 OpenGL Sample Implemenation (SI)
</a> is available.
108 The SI was written during the time that OpenGL was originally designed.
109 Unfortunately, development of the SI has stagnated.
110 Mesa is much more up to date with modern features and extensions.
114 <a href=
"http://ogl-es.sourceforge.net" target=
"_parent">Vincent
</a> is
115 an open-source implementation of OpenGL ES for mobile devices.
118 <a href=
"http://www.dsbox.com/minigl.html" target=
"_parent">miniGL
</a>
119 is a subset of OpenGL for PalmOS devices.
122 <a href=
"http://fabrice.bellard.free.fr/TinyGL/"
123 target=
"_parent">TinyGL
</a> is a subset of OpenGL.
127 <a href=
"http://softgl.studierstube.org/" target=
"_parent">SoftGL
</a>
128 is an OpenGL subset for mobile devices.
132 <a href=
"http://chromium.sourceforge.net/" target=
"_parent">Chromium
</a>
133 isn't a conventional OpenGL implementation (it's layered upon OpenGL),
134 but it does export the OpenGL API. It allows tiled rendering, sort-last
140 There may be other open OpenGL implementations, but Mesa is the most
141 popular and feature-complete.
149 </a><h1><a name=
"part2">2. Compilation and Installation Problems
</a></h1>
152 <h2><a name=
"part2">2.1 What's the easiest way to install Mesa?
</a></h2>
154 <a name=
"part2">If you're using a Linux-based system, your distro CD most likely already
155 has Mesa packages (like RPM or DEB) which you can easily install.
159 <h2><a name=
"part2">2.2 Running
<code>configure; make
</code> Doesn't Work
</a></h2>
161 <a name=
"part2">Unfortunately, the GNU autoconf/automake/libtool system doesn't seem to work
162 too well on non GNU/Linux systems, even after installing gmake, gcc, etc.
163 For that reason, Mesa's
<b>old-style
</b> makefile system is still included.
164 The old-style system uses good old traditional Makefiles. Try the following:
165 </a></p><pre><a name=
"part2"> cd Mesa-x.y.z
166 cp Makefile.X11 Makefile
169 <a name=
"part2">You'll see a list of system configurations from which to choose.
171 </a><pre><a name=
"part2"> make linux-x86
174 <a name=
"part2">If you're experienced with GNU autoconf/automake/libtool and think you can help
175 with maintence, contact the Mesa developers.
176 FYI, the Mesa developers generally don't use the autoconf/automake system.
177 We're especially annoyed with the fact that a +
5000-line script (libtool)
178 is needed to make shared libraries (ugh).
181 <h2><a name=
"part2">2.3 Mesa still doesn't compile
</a></h2>
183 <a name=
"part2">If the old-style Makefile system doesn't work either, make sure you have
184 the most recent version of Mesa.
185 Otherwise, file a bug report or post to the Mesa3d-users mailing list.
186 Give as much info as possible when describing your problem.
190 <h2><a name=
"part2">2.4 I get undefined symbols such as bgnpolygon, v3f, etc...
</a></h2>
192 <a name=
"part2">You're application is written in IRIS GL, not OpenGL.
193 IRIS GL was the predecessor to OpenGL and is a different thing (almost)
195 Mesa's not the solution.
199 <h2><a name=
"part2">2.5 Where is the GLUT library?
</a></h2>
201 <a name=
"part2">GLUT (OpenGL Utility Toolkit) is in the separate MesaDemos-x.y.z.tar.gz file.
202 If you don't already have GLUT installed, you should grab the MesaDemos
203 package and unpack it before compiling Mesa.
208 <h2><a name=
"part2">2.6 What's the proper place for the libraries and headers?
</a></h2>
210 <a name=
"part2">On Linux-based systems you'll want to follow the
211 </a><a href=
"http://oss.sgi.com/projects/ogl-sample/ABI/index.html"
212 target=
"_parent">Linux ABI
</a> standard.
213 Basically you'll want the following:
216 <li>/usr/include/GL/gl.h - the main OpenGL header
217 </li><li>/usr/include/GL/glu.h - the OpenGL GLU (utility) header
218 </li><li>/usr/include/GL/glx.h - the OpenGL GLX header
219 </li><li>/usr/include/GL/glext.h - the OpenGL extensions header
220 </li><li>/usr/include/GL/glxext.h - the OpenGL GLX extensions header
221 </li><li>/usr/include/GL/osmesa.h - the Mesa off-screen rendering header
222 </li><li>/usr/lib/libGL.so - a symlink to libGL.so
.1
223 </li><li>/usr/lib/libGL.so
.1 - a symlink to libGL.so
.1.xyz
224 </li><li>/usr/lib/libGL.so.xyz - the actual OpenGL/Mesa library. xyz denotes the
226 </li><li>/usr/lib/libGLU.so - a symlink to libGLU.so
.1
227 </li><li>/usr/lib/libGLU.so
.1 - a symlink to libGLU.so
.1.3.xyz
228 </li><li>/usr/lib/libGLU.so.xyz - the OpenGL Utility library. xyz denotes the Mesa
232 After installing XFree86 and the DRI drivers, some of these files
233 may be symlinks into the /usr/X11R6/ tree.
236 The old-style Makefile system doesn't install the Mesa libraries; it's
237 up to you to copy them (and the headers) to the right place.
240 The GLUT header and library should go in the same directories.
247 </a><h1><a name=
"part3">3. Runtime / Rendering Problems
</a></h1>
249 <h2><a name=
"part3">3.1 Rendering is slow / why isn't my graphics hardware being used?
</a></h2>
251 <a name=
"part3">Stand-alone Mesa (downloaded as MesaLib-x.y.z.tar.gz) doesn't have any
252 support for hardware acceleration (with the exception of the
3DFX Voodoo
256 <a name=
"part3">What you really want is a DRI or NVIDIA (or another vendor's OpenGL) driver
257 for your particular hardware.
260 <a name=
"part3">You can run the
<code>glxinfo
</code> program to learn about your OpenGL
262 Look for the GL_VENDOR and GL_RENDERER values.
263 That will identify who's OpenGL library you're using and what sort of
264 hardware it has detected.
267 <a name=
"part3">If your DRI-based driver isn't working, go to the
268 </a><a href=
"http://dri.sf.net/" target=
"_parent">DRI website
</a> for trouble-shooting information.
272 <h2>3.2 I'm seeing errors in depth (Z) buffering. Why?
</h2>
274 Make sure the ratio of the far to near clipping planes isn't too great.
276 <a href=
"http://www.sgi.com/software/opengl/advanced97/notes/node18.html"
278 here
</a> for details.
281 Mesa uses a
16-bit depth buffer by default which is smaller and faster
282 to clear than a
32-bit buffer but not as accurate.
283 If you need a deeper you can modify the parameters to
284 <code> glXChooseVisual
</code> in your code.
288 <h2>3.3 Why Isn't depth buffering working at all?
</h2>
290 Be sure you're requesting a depth buffered-visual. If you set the MESA_DEBUG
291 environment variable it will warn you about trying to enable depth testing
292 when you don't have a depth buffer.
294 <p>Specifically, make sure
<code>glutInitDisplayMode
</code> is being called
295 with
<code>GLUT_DEPTH
</code> or
<code>glXChooseVisual
</code> is being
296 called with a non-zero value for GLX_DEPTH_SIZE.
298 <p>This discussion applies to stencil buffers, accumulation buffers and
303 <h2>3.4 Why does glGetString() always return NULL?
</h2>
305 Be sure you have an active/current OpenGL rendering context before
310 <h2>3.5 GL_POINTS and GL_LINES don't touch the right pixels
</h2>
312 If you're trying to draw a filled region by using GL_POINTS or GL_LINES
313 and seeing holes or gaps it's because of a float-to-int rounding problem.
314 But this is not a bug.
315 See Appendix H of the OpenGL Programming Guide -
"OpenGL Correctness Tips".
316 Basically, applying a translation of (
0.375,
0.375,
0.0) to your coordinates
317 will fix the problem.
325 </a><h1><a name=
"part4">4. Developer Questions
</a></h1>
327 <h2><a name=
"part4">4.1 How can I contribute?
</a></h2>
329 <a name=
"part4">First, join the Mesa3d-dev mailing list. That's where Mesa development
333 <a name=
"part4">The
</a><a href=
"http://www.opengl.org/developers/documentation/specs.html" target=
"_parent">
334 OpenGL Specification
</a> is the bible for OpenGL implemention work.
337 <p>Most of the Mesa development work involves implementing new OpenGL
338 extensions, writing hardware drivers (for the DRI), and code optimization.
341 <h2>4.2 How do I write a new device driver?
</h2>
343 Unfortunately, writing a device driver isn't easy.
344 It requires detailed understanding of OpenGL, the Mesa code, and your
345 target hardware/operating system.
346 3D graphics are not simple.
349 The best way to get started is to use an existing driver as your starting
351 For a software driver, the X11 and OSMesa drivers are good examples.
352 For a hardware driver, the Radeon and R200 DRI drivers are good examples.
354 <p>The DRI website has more information about writing hardware drivers.
355 The process isn't well document because the Mesa driver interface changes
356 over time, and we seldome have spare time for writing documentation.
357 That being said, many people have managed to figure out the process.
360 Joining the appropriate mailing lists and asking questions (and searching
361 the archives) is a good way to get information.
365 <h2>4.3 Why isn't GL_EXT_texture_compression_s3tc implemented in Mesa and/or the DRI drivers?
</h2>
367 The
<a href=
"http://oss.sgi.com/projects/ogl-sample/registry/EXT/texture_compression_s3tc.txt" target=
"_parent">specification for the extension
</a>
368 indicates that there are intellectual property (IP) and/or patent issues
371 <p>We've been unsucessful in getting a response from S3 (or whoever owns
372 the IP nowadays) to indicate whether or not an open source project can
373 implement the extension (specifically the compression/decompression
377 Until we can get official permission to do so, this extension will not
378 be implemented in Mesa.