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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
24 <li><a href=
"#part1">High-level Questions and Answers
</a></li>
25 <li><a href=
"#part2">Compilation and Installation Problems
</a></li>
26 <li><a href=
"#part3">Runtime / Rendering Problems
</a></li>
27 <li><a href=
"#part4">Developer Questions
</a></li>
32 <h2 id=
"part1">1. High-level Questions and Answers
</h2>
34 <h3>1.1 What is Mesa?
</h3>
36 Mesa is an open-source implementation of the OpenGL specification.
37 OpenGL is a programming library for writing interactive
3D applications.
38 See the
<a href=
"https://www.opengl.org/">OpenGL website
</a> for more
42 Mesa
9.x supports the OpenGL
3.1 specification.
46 <h2>1.2 Does Mesa support/use graphics hardware?
</h2>
48 Yes. Specifically, Mesa serves as the OpenGL core for the open-source DRI
52 <li>See the
<a href=
"https://dri.freedesktop.org/">DRI website
</a>
53 for more information.
</li>
54 <li>See
<a href=
"https://01.org/linuxgraphics">01.org
</a>
55 for more information about Intel drivers.
</li>
56 <li>See
<a href=
"https://nouveau.freedesktop.org">nouveau.freedesktop.org
</a>
57 for more information about Nouveau drivers.
</li>
58 <li>See
<a href=
"https://www.x.org/wiki/RadeonFeature">www.x.org/wiki/RadeonFeature
</a>
59 for more information about Radeon drivers.
</li>
62 <h2>1.3 What purpose does Mesa serve today?
</h2>
64 Hardware-accelerated OpenGL implementations are available for most popular
65 operating systems today.
66 Still, Mesa serves at least these purposes:
69 <li>Mesa is used as the core of the open-source X.org DRI
72 <li>Mesa is quite portable and allows OpenGL to be used on systems
73 that have no other OpenGL solution.
75 <li>Software rendering with Mesa serves as a reference for validating the
78 <li>A software implementation of OpenGL is useful for experimentation,
79 such as testing new rendering techniques.
81 <li>Mesa can render images with deep color channels:
16-bit integer
82 and
32-bit floating point color channels are supported.
83 This capability is only now appearing in hardware.
85 <li>Mesa's internal limits (max lights, clip planes, texture size, etc) can be
86 changed for special needs (hardware limits are hard to overcome).
91 <h2>1.4 What's the difference between
"Stand-Alone" Mesa and the DRI drivers?
</h2>
93 <em>Stand-alone Mesa
</em> is the original incarnation of Mesa.
94 On systems running the X Window System it does all its rendering through
98 <li>The GLX API is supported, but it's really just an emulation of the
100 <li>The GLX wire protocol is not supported and there's no OpenGL extension
101 loaded by the X server.
102 <li>There is no hardware acceleration.
103 <li>The OpenGL library, libGL.so, contains everything (the programming API,
104 the GLX functions and all the rendering code).
107 Alternately, Mesa acts as the core for a number of OpenGL hardware drivers
108 within the DRI (Direct Rendering Infrastructure):
110 <li>The libGL.so library provides the GL and GLX API functions, a GLX
111 protocol encoder, and a device driver loader.
112 <li>The device driver modules (such as r200_dri.so) contain a built-in
113 copy of the core Mesa code.
114 <li>The X server loads the GLX module.
115 The GLX module decodes incoming GLX protocol and dispatches the commands
116 to a rendering module.
117 For the DRI, this module is basically a software Mesa renderer.
122 <h2>1.5 How do I upgrade my DRI installation to use a new Mesa release?
</h2>
124 This wasn't easy in the past.
125 Now, the DRI drivers are included in the Mesa tree and can be compiled
126 separately from the X server.
127 Just follow the Mesa
<a href=
"install.html">compilation instructions
</a>.
131 <h2>1.6 Are there other open-source implementations of OpenGL?
</h2>
133 Yes, SGI's
<a href=
"http://oss.sgi.com/projects/ogl-sample/index.html">
134 OpenGL Sample Implementation (SI)
</a> is available.
135 The SI was written during the time that OpenGL was originally designed.
136 Unfortunately, development of the SI has stagnated.
137 Mesa is much more up to date with modern features and extensions.
141 <a href=
"https://sourceforge.net/projects/ogl-es/">Vincent
</a> is
142 an open-source implementation of OpenGL ES for mobile devices.
145 <a href=
"http://www.dsbox.com/minigl.html">miniGL
</a>
146 is a subset of OpenGL for PalmOS devices.
149 <a href=
"http://bellard.org/TinyGL/">TinyGL
</a>
150 is a subset of OpenGL.
154 <a href=
"https://sourceforge.net/projects/softgl/">SoftGL
</a>
155 is an OpenGL subset for mobile devices.
159 <a href=
"http://chromium.sourceforge.net/">Chromium
</a>
160 isn't a conventional OpenGL implementation (it's layered upon OpenGL),
161 but it does export the OpenGL API. It allows tiled rendering, sort-last
166 <a href=
"http://www.ticalc.org/archives/files/fileinfo/361/36173.html">ClosedGL
</a>
167 is an OpenGL subset library for TI graphing calculators.
171 There may be other open OpenGL implementations, but Mesa is the most
172 popular and feature-complete.
181 <h2 id=
"part2">2. Compilation and Installation Problems
</h2>
184 <h3>2.1 What's the easiest way to install Mesa?
</h3>
186 If you're using a Linux-based system, your distro CD most likely already
187 has Mesa packages (like RPM or DEB) which you can easily install.
191 <h3>2.2 I get undefined symbols such as bgnpolygon, v3f, etc...
</h3>
193 You're application is written in IRIS GL, not OpenGL.
194 IRIS GL was the predecessor to OpenGL and is a different thing (almost)
196 Mesa's not the solution.
200 <h3>2.3 Where is the GLUT library?
</h3>
202 GLUT (OpenGL Utility Toolkit) is no longer in the separate MesaGLUT-x.y.z.tar.gz file.
203 If you don't already have GLUT installed, you should grab
204 <a href=
"http://freeglut.sourceforge.net/">freeglut
</a>.
208 <h3>2.4 Where is the GLw library?
</h3>
210 GLw (OpenGL widget library) is now available from a separate
<a href=
"https://cgit.freedesktop.org/mesa/glw/">git repository
</a>. Unless you're using very old Xt/Motif applications with OpenGL, you shouldn't need it.
214 <h2>2.5 What's the proper place for the libraries and headers?
</h2>
216 On Linux-based systems you'll want to follow the
217 <a href=
"http://oss.sgi.com/projects/ogl-sample/ABI/index.html">Linux ABI
</a> standard.
218 Basically you'll want the following:
221 <li>/usr/include/GL/gl.h - the main OpenGL header
222 </li><li>/usr/include/GL/glu.h - the OpenGL GLU (utility) header
223 </li><li>/usr/include/GL/glx.h - the OpenGL GLX header
224 </li><li>/usr/include/GL/glext.h - the OpenGL extensions header
225 </li><li>/usr/include/GL/glxext.h - the OpenGL GLX extensions header
226 </li><li>/usr/include/GL/osmesa.h - the Mesa off-screen rendering header
227 </li><li>/usr/lib/libGL.so - a symlink to libGL.so
.1
228 </li><li>/usr/lib/libGL.so
.1 - a symlink to libGL.so
.1.xyz
229 </li><li>/usr/lib/libGL.so.xyz - the actual OpenGL/Mesa library. xyz denotes the
233 When configuring Mesa, there are three meson options that affect the install
234 location that you should take care with:
<code>--prefix
</code>,
235 <code>--libdir
</code>, and
<code>-D dri-drivers-path
</code>. To install Mesa
236 into the system location where it will be available for all programs to use, set
237 <code>--prefix=/usr
</code>. Set
<code>--libdir
</code> to where your Linux
238 distribution installs system libraries, usually either
<code>/usr/lib
</code> or
239 <code>/usr/lib64
</code>. Set
<code>-D dri-drivers-path
</code> to the directory
240 where your Linux distribution installs DRI drivers. To find your system's DRI
241 driver directory, try executing
<code>find /usr -type d -name dri
</code>. For
242 example, if the
<code>find
</code> command listed
<code>/usr/lib64/dri
</code>,
243 then set
<code>-D dri-drivers-path=/usr/lib64/dri
</code>.
246 After determining the correct values for the install location, configure Mesa
247 with
<code>meson configure --prefix=/usr --libdir=xxx -D dri-drivers-path=xxx
</code>
248 and then install with
<code>sudo ninja install
</code>.
254 <h2 id=
"part3">3. Runtime / Rendering Problems
</h2>
256 <h3>3.1 Rendering is slow / why isn't my graphics hardware being used?
</h3>
258 If Mesa can't use its hardware accelerated drivers it falls back on one of its software renderers.
259 (eg. classic swrast, softpipe or llvmpipe)
262 You can run the
<code>glxinfo
</code> program to learn about your OpenGL
264 Look for the
<code>OpenGL vendor
</code> and
<code>OpenGL renderer
</code> values.
265 That will identify who's OpenGL library with which driver you're using and what sort of
266 hardware it has detected.
269 If you're using a hardware accelerated driver you want
<code>direct rendering: Yes
</code>.
272 If your DRI-based driver isn't working, go to the
273 <a href=
"https://dri.freedesktop.org/">DRI website
</a> for trouble-shooting information.
277 <h3>3.2 I'm seeing errors in depth (Z) buffering. Why?
</h3>
279 Make sure the ratio of the far to near clipping planes isn't too great.
281 <a href=
"https://www.opengl.org/resources/faq/technical/depthbuffer.htm#0040">here
</a>
285 Mesa uses a
16-bit depth buffer by default which is smaller and faster
286 to clear than a
32-bit buffer but not as accurate.
287 If you need a deeper you can modify the parameters to
288 <code> glXChooseVisual
</code> in your code.
292 <h3>3.3 Why Isn't depth buffering working at all?
</h3>
294 Be sure you're requesting a depth buffered-visual. If you set the MESA_DEBUG
295 environment variable it will warn you about trying to enable depth testing
296 when you don't have a depth buffer.
298 <p>Specifically, make sure
<code>glutInitDisplayMode
</code> is being called
299 with
<code>GLUT_DEPTH
</code> or
<code>glXChooseVisual
</code> is being
300 called with a non-zero value for GLX_DEPTH_SIZE.
302 <p>This discussion applies to stencil buffers, accumulation buffers and
307 <h3>3.4 Why does glGetString() always return NULL?
</h3>
309 Be sure you have an active/current OpenGL rendering context before
314 <h3>3.5 GL_POINTS and GL_LINES don't touch the right pixels
</h3>
316 If you're trying to draw a filled region by using GL_POINTS or GL_LINES
317 and seeing holes or gaps it's because of a float-to-int rounding problem.
318 But this is not a bug.
319 See Appendix H of the OpenGL Programming Guide -
"OpenGL Correctness Tips".
320 Basically, applying a translation of (
0.375,
0.375,
0.0) to your coordinates
321 will fix the problem.
328 <h2 id=
"part4">4. Developer Questions
</h2>
330 <h3>4.1 How can I contribute?
</h3>
332 First, join the
<a href=
"lists.html">mesa-dev mailing list
</a>.
333 That's where Mesa development is discussed.
336 The
<a href=
"https://www.opengl.org/documentation">
337 OpenGL Specification
</a> is the bible for OpenGL implementation work.
340 <p>Most of the Mesa development work involves implementing new OpenGL
341 extensions, writing hardware drivers (for the DRI), and code optimization.
344 <h3>4.2 How do I write a new device driver?
</h3>
346 Unfortunately, writing a device driver isn't easy.
347 It requires detailed understanding of OpenGL, the Mesa code, and your
348 target hardware/operating system.
349 3D graphics are not simple.
352 The best way to get started is to use an existing driver as your starting
354 For a classic hardware driver, the i965 driver is a good example.
355 For a Gallium3D hardware driver, the r300g, r600g and the i915g are good examples.
357 <p>The DRI website has more information about writing hardware drivers.
358 The process isn't well document because the Mesa driver interface changes
359 over time, and we seldom have spare time for writing documentation.
360 That being said, many people have managed to figure out the process.
363 Joining the appropriate mailing lists and asking questions (and searching
364 the archives) is a good way to get information.
368 <h3>4.3 Why isn't GL_EXT_texture_compression_s3tc implemented in Mesa?
</h3>
370 Oh but it is! Prior to
2nd October
2017, the Mesa project did not include s3tc
371 support due to intellectual property (IP) and/or patent issues around the s3tc
375 As of Mesa
17.3.0, Mesa now officially supports s3tc, as the patent has expired.
378 In versions prior to this, a
3rd party
<a href=
"https://dri.freedesktop.org/wiki/S3TC">
379 plug-in library
</a> was required.