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11 The Mesa
3D Graphics Library
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17 <h1>Frequently Asked Questions
</h1>
18 Last updated:
19 September
2018
22 <li><a href=
"#part1">High-level Questions and Answers
</a></li>
23 <li><a href=
"#part2">Compilation and Installation Problems
</a></li>
24 <li><a href=
"#part3">Runtime / Rendering Problems
</a></li>
25 <li><a href=
"#part4">Developer Questions
</a></li>
28 <h2 id=
"part1">1. High-level Questions and Answers
</h2>
30 <h3>1.1 What is Mesa?
</h3>
32 Mesa is an open-source implementation of the OpenGL specification.
33 OpenGL is a programming library for writing interactive
3D applications.
34 See the
<a href=
"https://www.opengl.org/">OpenGL website
</a> for more
38 Mesa
9.x supports the OpenGL
3.1 specification.
42 <h2>1.2 Does Mesa support/use graphics hardware?
</h2>
44 Yes. Specifically, Mesa serves as the OpenGL core for the open-source DRI
48 <li>See the
<a href=
"https://dri.freedesktop.org/">DRI website
</a>
49 for more information.
</li>
50 <li>See
<a href=
"https://01.org/linuxgraphics">01.org
</a>
51 for more information about Intel drivers.
</li>
52 <li>See
<a href=
"https://nouveau.freedesktop.org">nouveau.freedesktop.org
</a>
53 for more information about Nouveau drivers.
</li>
54 <li>See
<a href=
"https://www.x.org/wiki/RadeonFeature">www.x.org/wiki/RadeonFeature
</a>
55 for more information about Radeon drivers.
</li>
58 <h2>1.3 What purpose does Mesa serve today?
</h2>
60 Hardware-accelerated OpenGL implementations are available for most popular
61 operating systems today.
62 Still, Mesa serves at least these purposes:
65 <li>Mesa is used as the core of the open-source X.org DRI
68 <li>Mesa is quite portable and allows OpenGL to be used on systems
69 that have no other OpenGL solution.
71 <li>Software rendering with Mesa serves as a reference for validating the
74 <li>A software implementation of OpenGL is useful for experimentation,
75 such as testing new rendering techniques.
77 <li>Mesa can render images with deep color channels:
16-bit integer
78 and
32-bit floating point color channels are supported.
79 This capability is only now appearing in hardware.
81 <li>Mesa's internal limits (max lights, clip planes, texture size, etc) can be
82 changed for special needs (hardware limits are hard to overcome).
87 <h2>1.4 What's the difference between
"Stand-Alone" Mesa and the DRI drivers?
</h2>
89 <em>Stand-alone Mesa
</em> is the original incarnation of Mesa.
90 On systems running the X Window System it does all its rendering through
94 <li>The GLX API is supported, but it's really just an emulation of the
96 <li>The GLX wire protocol is not supported and there's no OpenGL extension
97 loaded by the X server.
98 <li>There is no hardware acceleration.
99 <li>The OpenGL library,
<code>libGL.so
</code>, contains everything (the
100 programming API, the GLX functions and all the rendering code).
103 Alternately, Mesa acts as the core for a number of OpenGL hardware drivers
104 within the DRI (Direct Rendering Infrastructure):
106 <li>The
<code>libGL.so
</code> library provides the GL and GLX API functions,
107 a GLX protocol encoder, and a device driver loader.
108 <li>The device driver modules (such as
<code>r200_dri.so
</code>) contain
109 a built-in copy of the core Mesa code.
110 <li>The X server loads the GLX module.
111 The GLX module decodes incoming GLX protocol and dispatches the commands
112 to a rendering module.
113 For the DRI, this module is basically a software Mesa renderer.
118 <h2>1.5 How do I upgrade my DRI installation to use a new Mesa release?
</h2>
120 This wasn't easy in the past.
121 Now, the DRI drivers are included in the Mesa tree and can be compiled
122 separately from the X server.
123 Just follow the Mesa
<a href=
"install.html">compilation instructions
</a>.
127 <h2>1.6 Are there other open-source implementations of OpenGL?
</h2>
129 Yes, SGI's
<a href=
"http://oss.sgi.com/projects/ogl-sample/index.html">
130 OpenGL Sample Implementation (SI)
</a> is available.
131 The SI was written during the time that OpenGL was originally designed.
132 Unfortunately, development of the SI has stagnated.
133 Mesa is much more up to date with modern features and extensions.
137 <a href=
"https://sourceforge.net/projects/ogl-es/">Vincent
</a> is
138 an open-source implementation of OpenGL ES for mobile devices.
141 <a href=
"http://www.dsbox.com/minigl.html">miniGL
</a>
142 is a subset of OpenGL for PalmOS devices.
145 <a href=
"http://bellard.org/TinyGL/">TinyGL
</a>
146 is a subset of OpenGL.
150 <a href=
"https://sourceforge.net/projects/softgl/">SoftGL
</a>
151 is an OpenGL subset for mobile devices.
155 <a href=
"http://chromium.sourceforge.net/">Chromium
</a>
156 isn't a conventional OpenGL implementation (it's layered upon OpenGL),
157 but it does export the OpenGL API. It allows tiled rendering, sort-last
162 <a href=
"http://www.ticalc.org/archives/files/fileinfo/361/36173.html">ClosedGL
</a>
163 is an OpenGL subset library for TI graphing calculators.
167 There may be other open OpenGL implementations, but Mesa is the most
168 popular and feature-complete.
172 <h2 id=
"part2">2. Compilation and Installation Problems
</h2>
174 <h3>2.1 What's the easiest way to install Mesa?
</h3>
176 If you're using a Linux-based system, your distro CD most likely already
177 has Mesa packages (like RPM or DEB) which you can easily install.
181 <h3>2.2 I get undefined symbols such as bgnpolygon, v3f, etc...
</h3>
183 You're application is written in IRIS GL, not OpenGL.
184 IRIS GL was the predecessor to OpenGL and is a different thing (almost)
186 Mesa's not the solution.
190 <h3>2.3 Where is the GLUT library?
</h3>
192 GLUT (OpenGL Utility Toolkit) is no longer in the separate
193 <code>MesaGLUT-x.y.z.tar.gz
</code> file.
194 If you don't already have GLUT installed, you should grab
195 <a href=
"http://freeglut.sourceforge.net/">freeglut
</a>.
199 <h3>2.4 Where is the GLw library?
</h3>
201 GLw (OpenGL widget library) is now available from a separate
<a href=
"https://gitlab.freedesktop.org/mesa/glw">git repository
</a>. Unless you're using very old Xt/Motif applications with OpenGL, you shouldn't need it.
205 <h2>2.5 What's the proper place for the libraries and headers?
</h2>
207 On Linux-based systems you'll want to follow the
208 <a href=
"https://www.khronos.org/registry/OpenGL/ABI/">Linux ABI
</a> standard.
209 Basically you'll want the following:
212 <dt><code>/usr/include/GL/gl.h
</code></dt>
213 <dd>the main OpenGL header
</dd>
214 <dt><code>/usr/include/GL/glu.h
</code></dt>
215 <dd>the OpenGL GLU (utility) header
</dd>
216 <dt><code>/usr/include/GL/glx.h
</code></dt>
217 <dd>the OpenGL GLX header
</dd>
218 <dt><code>/usr/include/GL/glext.h
</code></dt>
219 <dd>the OpenGL extensions header
</dd>
220 <dt><code>/usr/include/GL/glxext.h
</code></dt>
221 <dd>the OpenGL GLX extensions header
</dd>
222 <dt><code>/usr/include/GL/osmesa.h
</code></dt>
223 <dd>the Mesa off-screen rendering header
</dd>
224 <dt><code>/usr/lib/libGL.so
</code></dt>
225 <dd>a symlink to
<code>libGL.so
.1</code></dd>
226 <dt><code>/usr/lib/libGL.so
.1</code></dt>
227 <dd>a symlink to
<code>libGL.so
.1.xyz
</code></dd>
228 <dt><code>/usr/lib/libGL.so.xyz
</code></dt>
229 <dd>the actual OpenGL/Mesa library. xyz denotes the
234 When configuring Mesa, there are three meson options that affect the install
235 location that you should take care with:
<code>--prefix
</code>,
236 <code>--libdir
</code>, and
<code>-D dri-drivers-path
</code>. To install Mesa
237 into the system location where it will be available for all programs to use, set
238 <code>--prefix=/usr
</code>. Set
<code>--libdir
</code> to where your Linux
239 distribution installs system libraries, usually either
<code>/usr/lib
</code> or
240 <code>/usr/lib64
</code>. Set
<code>-D dri-drivers-path
</code> to the directory
241 where your Linux distribution installs DRI drivers. To find your system's DRI
242 driver directory, try executing
<code>find /usr -type d -name dri
</code>. For
243 example, if the
<code>find
</code> command listed
<code>/usr/lib64/dri
</code>,
244 then set
<code>-D dri-drivers-path=/usr/lib64/dri
</code>.
247 After determining the correct values for the install location, configure Mesa
248 with
<code>meson configure --prefix=/usr --libdir=xxx -D dri-drivers-path=xxx
</code>
249 and then install with
<code>sudo ninja install
</code>.
253 <h2 id=
"part3">3. Runtime / Rendering Problems
</h2>
255 <h3>3.1 Rendering is slow / why isn't my graphics hardware being used?
</h3>
257 If Mesa can't use its hardware accelerated drivers it falls back on one of its software renderers.
258 (eg. classic swrast, softpipe or llvmpipe)
261 You can run the
<code>glxinfo
</code> program to learn about your OpenGL
263 Look for the
<code>OpenGL vendor
</code> and
<code>OpenGL renderer
</code> values.
264 That will identify who's OpenGL library with which driver you're using and what sort of
265 hardware it has detected.
268 If you're using a hardware accelerated driver you want
<code>direct rendering: Yes
</code>.
271 If your DRI-based driver isn't working, go to the
272 <a href=
"https://dri.freedesktop.org/">DRI website
</a> for trouble-shooting information.
276 <h3>3.2 I'm seeing errors in depth (Z) buffering. Why?
</h3>
278 Make sure the ratio of the far to near clipping planes isn't too great.
280 <a href=
"https://www.opengl.org/archives/resources/faq/technical/depthbuffer.htm#0040">here
</a>
284 Mesa uses a
16-bit depth buffer by default which is smaller and faster
285 to clear than a
32-bit buffer but not as accurate.
286 If you need a deeper you can modify the parameters to
287 <code>glXChooseVisual
</code> in your code.
291 <h3>3.3 Why Isn't depth buffering working at all?
</h3>
293 Be sure you're requesting a depth buffered-visual. If you set the
294 <code>MESA_DEBUG
</code> environment variable it will warn you about trying
295 to enable depth testing when you don't have a depth buffer.
297 <p>Specifically, make sure
<code>glutInitDisplayMode
</code> is being called
298 with
<code>GLUT_DEPTH
</code> or
<code>glXChooseVisual
</code> is being
299 called with a non-zero value for
<code>GLX_DEPTH_SIZE
</code>.
301 <p>This discussion applies to stencil buffers, accumulation buffers and
306 <h3>3.4 Why does
<code>glGetString()
</code> always return
<code>NULL
</code>?
</h3>
308 Be sure you have an active/current OpenGL rendering context before
309 calling
<code>glGetString
</code>.
313 <h3>3.5 <code>GL_POINTS
</code> and
<code>GL_LINES
</code> don't touch the
316 If you're trying to draw a filled region by using
<code>GL_POINTS
</code> or
317 <code>GL_LINES
</code> and seeing holes or gaps it's because of a float-to-int
318 rounding problem. But this is not a bug. See Appendix H of the OpenGL
319 Programming Guide -
"OpenGL Correctness Tips". Basically, applying a
320 translation of (
0.375,
0.375,
0.0) to your coordinates will fix the problem.
324 <h2 id=
"part4">4. Developer Questions
</h2>
326 <h3>4.1 How can I contribute?
</h3>
328 First, join the
<a href=
"lists.html">mesa-dev mailing list
</a>.
329 That's where Mesa development is discussed.
332 The
<a href=
"https://www.opengl.org/documentation">
333 OpenGL Specification
</a> is the bible for OpenGL implementation work.
336 <p>Most of the Mesa development work involves implementing new OpenGL
337 extensions, writing hardware drivers (for the DRI), and code optimization.
340 <h3>4.2 How do I write a new device driver?
</h3>
342 Unfortunately, writing a device driver isn't easy.
343 It requires detailed understanding of OpenGL, the Mesa code, and your
344 target hardware/operating system.
345 3D graphics are not simple.
348 The best way to get started is to use an existing driver as your starting
350 For a classic hardware driver, the i965 driver is a good example.
351 For a Gallium3D hardware driver, the r300g, r600g and the i915g are good examples.
353 <p>The DRI website has more information about writing hardware drivers.
354 The process isn't well document because the Mesa driver interface changes
355 over time, and we seldom have spare time for writing documentation.
356 That being said, many people have managed to figure out the process.
359 Joining the appropriate mailing lists and asking questions (and searching
360 the archives) is a good way to get information.
364 <h3>4.3 Why isn't
<code>GL_EXT_texture_compression_s3tc
</code> implemented in
367 Oh but it is! Prior to
2nd October
2017, the Mesa project did not include s3tc
368 support due to intellectual property (IP) and/or patent issues around the s3tc
372 As of Mesa
17.3.0, Mesa now officially supports s3tc, as the patent has expired.
375 In versions prior to this, a
3rd party
<a href=
"https://dri.freedesktop.org/wiki/S3TC">
376 plug-in library
</a> was required.