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gerrit-public.fairphone.software / platform / external / mesa3d / da4994f25201ff0e8b0290ec520549ef848fda9f / . / docs / faq.html
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Andreas Bollecd5c7c2012-06-12 09:05:03 +0200[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
2<html lang="en">
3<head>
4 <meta http-equiv="content-type" content="text/html; charset=utf-8">
5 <title>Mesa FAQ</title>
6 <link rel="stylesheet" type="text/css" href="mesa.css">
7</head>
8<body>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]9
Andreas Bollb5da52a2012-09-18 18:57:02 +0200[diff] [blame]10<div class="header">
11 <h1>The Mesa 3D Graphics Library</h1>
12</div>
13
14<iframe src="contents.html"></iframe>
15<div class="content">
16
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]17<center>
18<h1>Mesa Frequently Asked Questions</h1>
Stuart Youngc95dd962018-09-20 17:12:43 +1000[diff] [blame]19Last updated: 19 September 2018
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]20</center>
21
22<br>
23<br>
24<h2>Index</h2>
Erik Faye-Lundda4994f2019-04-18 13:44:10 +0200[diff] [blame^]25<ol>
26 <li><a href="#part1">High-level Questions and Answers</a></li>
27 <li><a href="#part2">Compilation and Installation Problems</a></li>
28 <li><a href="#part3">Runtime / Rendering Problems</a></li>
29 <li><a href="#part4">Developer Questions</a></li>
30</ol>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]31<br>
32<br>
33
34
35
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]36<h1 id="part1">1. High-level Questions and Answers</h1>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]37
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]38<h2>1.1 What is Mesa?</h2>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]39<p>
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]40Mesa is an open-source implementation of the OpenGL specification.
Brian Paula376e332003-03-30 16:54:36 +0000[diff] [blame]41OpenGL is a programming library for writing interactive 3D applications.
Eric Engestrom30cf9ff2017-02-09 02:10:17 +0000[diff] [blame]42See the <a href="https://www.opengl.org/">OpenGL website</a> for more
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]43information.
44</p>
45<p>
Andreas Boll5abb1f82012-09-19 18:22:37 +0200[diff] [blame]46Mesa 9.x supports the OpenGL 3.1 specification.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]47</p>
48
49
50<h2>1.2 Does Mesa support/use graphics hardware?</h2>
51<p>
Brian Paul7e4cc1c2005-10-24 23:33:27 +0000[diff] [blame]52Yes. Specifically, Mesa serves as the OpenGL core for the open-source DRI
Andreas Boll8504f182012-09-20 16:23:15 +0200[diff] [blame]53drivers for X.org.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]54</p>
Andreas Boll8504f182012-09-20 16:23:15 +0200[diff] [blame]55<ul>
Eric Engestrom30cf9ff2017-02-09 02:10:17 +0000[diff] [blame]56 <li>See the <a href="https://dri.freedesktop.org/">DRI website</a>
Andreas Boll8504f182012-09-20 16:23:15 +0200[diff] [blame]57 for more information.</li>
Eric Engestrom771f6db2016-07-06 17:09:15 +0100[diff] [blame]58 <li>See <a href="https://01.org/linuxgraphics">01.org</a>
Andreas Boll8504f182012-09-20 16:23:15 +0200[diff] [blame]59 for more information about Intel drivers.</li>
Eric Engestrom30cf9ff2017-02-09 02:10:17 +0000[diff] [blame]60 <li>See <a href="https://nouveau.freedesktop.org">nouveau.freedesktop.org</a>
Andreas Boll8504f182012-09-20 16:23:15 +0200[diff] [blame]61 for more information about Nouveau drivers.</li>
Eric Engestrom30cf9ff2017-02-09 02:10:17 +0000[diff] [blame]62 <li>See <a href="https://www.x.org/wiki/RadeonFeature">www.x.org/wiki/RadeonFeature</a>
Andreas Boll8504f182012-09-20 16:23:15 +0200[diff] [blame]63 for more information about Radeon drivers.</li>
64</ul>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]65
Brian Paul65b79052004-11-22 17:49:15 +0000[diff] [blame]66<h2>1.3 What purpose does Mesa serve today?</h2>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]67<p>
Brian Paula376e332003-03-30 16:54:36 +0000[diff] [blame]68Hardware-accelerated OpenGL implementations are available for most popular
69operating systems today.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]70Still, Mesa serves at least these purposes:
71</p>
72<ul>
Andreas Boll8504f182012-09-20 16:23:15 +0200[diff] [blame]73<li>Mesa is used as the core of the open-source X.org DRI
Brian Paul7e4cc1c2005-10-24 23:33:27 +0000[diff] [blame]74 hardware drivers.
Brian Paula376e332003-03-30 16:54:36 +0000[diff] [blame]75</li>
76<li>Mesa is quite portable and allows OpenGL to be used on systems
77 that have no other OpenGL solution.
78</li>
79<li>Software rendering with Mesa serves as a reference for validating the
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]80 hardware drivers.
Brian Paula376e332003-03-30 16:54:36 +0000[diff] [blame]81</li>
82<li>A software implementation of OpenGL is useful for experimentation,
83 such as testing new rendering techniques.
84</li>
85<li>Mesa can render images with deep color channels: 16-bit integer
86 and 32-bit floating point color channels are supported.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]87 This capability is only now appearing in hardware.
Brian Paula376e332003-03-30 16:54:36 +0000[diff] [blame]88</li>
89<li>Mesa's internal limits (max lights, clip planes, texture size, etc) can be
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]90 changed for special needs (hardware limits are hard to overcome).
Brian Paula376e332003-03-30 16:54:36 +0000[diff] [blame]91</li>
92</ul>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]93
Brian Paul65b79052004-11-22 17:49:15 +0000[diff] [blame]94
Andreas Boll5abb1f82012-09-19 18:22:37 +0200[diff] [blame]95<h2>1.4 What's the difference between "Stand-Alone" Mesa and the DRI drivers?</h2>
Brian Paul65b79052004-11-22 17:49:15 +0000[diff] [blame]96<p>
97<em>Stand-alone Mesa</em> is the original incarnation of Mesa.
Brian Paul7e4cc1c2005-10-24 23:33:27 +0000[diff] [blame]98On systems running the X Window System it does all its rendering through
99the Xlib API:
Andreas Bolldf2be222012-06-12 09:05:22 +0200[diff] [blame]100</p>
Brian Paul65b79052004-11-22 17:49:15 +0000[diff] [blame]101<ul>
102<li>The GLX API is supported, but it's really just an emulation of the
103 real thing.
104<li>The GLX wire protocol is not supported and there's no OpenGL extension
105 loaded by the X server.
106<li>There is no hardware acceleration.
107<li>The OpenGL library, libGL.so, contains everything (the programming API,
108 the GLX functions and all the rendering code).
109</ul>
Brian Paul65b79052004-11-22 17:49:15 +0000[diff] [blame]110<p>
111Alternately, Mesa acts as the core for a number of OpenGL hardware drivers
112within the DRI (Direct Rendering Infrastructure):
113<ul>
114<li>The libGL.so library provides the GL and GLX API functions, a GLX
115 protocol encoder, and a device driver loader.
116<li>The device driver modules (such as r200_dri.so) contain a built-in
117 copy of the core Mesa code.
118<li>The X server loads the GLX module.
119 The GLX module decodes incoming GLX protocol and dispatches the commands
120 to a rendering module.
121 For the DRI, this module is basically a software Mesa renderer.
122</ul>
123
124
125
126<h2>1.5 How do I upgrade my DRI installation to use a new Mesa release?</h2>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]127<p>
Brian Paul7e4cc1c2005-10-24 23:33:27 +0000[diff] [blame]128This wasn't easy in the past.
129Now, the DRI drivers are included in the Mesa tree and can be compiled
130separately from the X server.
131Just follow the Mesa <a href="install.html">compilation instructions</a>.
Brian Paul824a4fc2003-08-06 19:05:26 +0000[diff] [blame]132</p>
133
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]134
Brian Paul65b79052004-11-22 17:49:15 +0000[diff] [blame]135<h2>1.6 Are there other open-source implementations of OpenGL?</h2>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]136<p>
Andreas Bolla73c59b2012-09-18 19:31:28 +0200[diff] [blame]137Yes, SGI's <a href="http://oss.sgi.com/projects/ogl-sample/index.html">
Nathan Kidd0691b372014-01-03 16:44:00 -0700[diff] [blame]138OpenGL Sample Implementation (SI)</a> is available.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]139The SI was written during the time that OpenGL was originally designed.
140Unfortunately, development of the SI has stagnated.
141Mesa is much more up to date with modern features and extensions.
142</p>
Brian Paul186d4d82004-04-27 12:55:08 +0000[diff] [blame]143
144<p>
Eric Engestrom30cf9ff2017-02-09 02:10:17 +0000[diff] [blame]145<a href="https://sourceforge.net/projects/ogl-es/">Vincent</a> is
Brian Paul186d4d82004-04-27 12:55:08 +0000[diff] [blame]146an open-source implementation of OpenGL ES for mobile devices.
147
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]148<p>
Andreas Bolla73c59b2012-09-18 19:31:28 +0200[diff] [blame]149<a href="http://www.dsbox.com/minigl.html">miniGL</a>
Brian Paul7df4f952003-11-25 21:13:26 +0000[diff] [blame]150is a subset of OpenGL for PalmOS devices.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]151
Brian Paul7df4f952003-11-25 21:13:26 +0000[diff] [blame]152<p>
Andreas Boll8504f182012-09-20 16:23:15 +0200[diff] [blame]153<a href="http://bellard.org/TinyGL/">TinyGL</a>
Andreas Bolla73c59b2012-09-18 19:31:28 +0200[diff] [blame]154is a subset of OpenGL.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]155</p>
Brian Paul7df4f952003-11-25 21:13:26 +0000[diff] [blame]156
157<p>
Eric Engestrom30cf9ff2017-02-09 02:10:17 +0000[diff] [blame]158<a href="https://sourceforge.net/projects/softgl/">SoftGL</a>
Brian Paul7df4f952003-11-25 21:13:26 +0000[diff] [blame]159is an OpenGL subset for mobile devices.
160</p>
161
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]162<p>
Andreas Bolla73c59b2012-09-18 19:31:28 +0200[diff] [blame]163<a href="http://chromium.sourceforge.net/">Chromium</a>
Brian Paulacbc1e02003-11-26 18:10:31 +0000[diff] [blame]164isn't a conventional OpenGL implementation (it's layered upon OpenGL),
165but it does export the OpenGL API. It allows tiled rendering, sort-last
166rendering, etc.
167</p>
168
Brian Paulacbc1e02003-11-26 18:10:31 +0000[diff] [blame]169<p>
Andreas Bolla73c59b2012-09-18 19:31:28 +0200[diff] [blame]170<a href="http://www.ticalc.org/archives/files/fileinfo/361/36173.html">ClosedGL</a>
171is an OpenGL subset library for TI graphing calculators.
Brian Paul0c656042006-06-08 19:59:41 +0000[diff] [blame]172</p>
173
174<p>
Brian Paulacbc1e02003-11-26 18:10:31 +0000[diff] [blame]175There may be other open OpenGL implementations, but Mesa is the most
176popular and feature-complete.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]177</p>
178
Brian Paul65b79052004-11-22 17:49:15 +0000[diff] [blame]179
180
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]181<br>
182<br>
183
184
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]185<h1 id="part2">2. Compilation and Installation Problems</h1>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]186
187
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]188<h2>2.1 What's the easiest way to install Mesa?</h2>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]189<p>
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]190If you're using a Linux-based system, your distro CD most likely already
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]191has Mesa packages (like RPM or DEB) which you can easily install.
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]192</p>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]193
194
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]195<h2>2.2 I get undefined symbols such as bgnpolygon, v3f, etc...</h2>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]196<p>
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]197You're application is written in IRIS GL, not OpenGL.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]198IRIS GL was the predecessor to OpenGL and is a different thing (almost)
199entirely.
200Mesa's not the solution.
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]201</p>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]202
203
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]204<h2>2.3 Where is the GLUT library?</h2>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]205<p>
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]206GLUT (OpenGL Utility Toolkit) is no longer in the separate MesaGLUT-x.y.z.tar.gz file.
José Fonseca9a7f84d2011-07-14 17:28:52 +0100[diff] [blame]207If you don't already have GLUT installed, you should grab
208<a href="http://freeglut.sourceforge.net/">freeglut</a>.
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]209</p>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]210
211
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]212<h2>2.4 Where is the GLw library?</h2>
Kenneth Graunkec5481922011-08-05 16:59:04 -0700[diff] [blame]213<p>
Eric Engestrom30cf9ff2017-02-09 02:10:17 +0000[diff] [blame]214GLw (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.
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]215</p>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]216
Kenneth Graunkec5481922011-08-05 16:59:04 -0700[diff] [blame]217
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]218<h2>2.5 What's the proper place for the libraries and headers?</h2>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]219<p>
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]220On Linux-based systems you'll want to follow the
Andreas Bolla73c59b2012-09-18 19:31:28 +0200[diff] [blame]221<a href="http://oss.sgi.com/projects/ogl-sample/ABI/index.html">Linux ABI</a> standard.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]222Basically you'll want the following:
223</p>
224<ul>
225<li>/usr/include/GL/gl.h - the main OpenGL header
226</li><li>/usr/include/GL/glu.h - the OpenGL GLU (utility) header
227</li><li>/usr/include/GL/glx.h - the OpenGL GLX header
228</li><li>/usr/include/GL/glext.h - the OpenGL extensions header
229</li><li>/usr/include/GL/glxext.h - the OpenGL GLX extensions header
230</li><li>/usr/include/GL/osmesa.h - the Mesa off-screen rendering header
231</li><li>/usr/lib/libGL.so - a symlink to libGL.so.1
232</li><li>/usr/lib/libGL.so.1 - a symlink to libGL.so.1.xyz
233</li><li>/usr/lib/libGL.so.xyz - the actual OpenGL/Mesa library. xyz denotes the
234Mesa version number.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]235</li></ul>
236<p>
Eric Engestrom46d68832019-04-24 13:16:57 +0100[diff] [blame]237When configuring Mesa, there are three meson options that affect the install
Andreas Bollb534c392012-10-05 23:14:10 +0200[diff] [blame]238location that you should take care with: <code>--prefix</code>,
Eric Engestrom46d68832019-04-24 13:16:57 +0100[diff] [blame]239<code>--libdir</code>, and <code>-D dri-drivers-path</code>. To install Mesa
Andreas Bollb534c392012-10-05 23:14:10 +0200[diff] [blame]240into the system location where it will be available for all programs to use, set
241<code>--prefix=/usr</code>. Set <code>--libdir</code> to where your Linux
242distribution installs system libraries, usually either <code>/usr/lib</code> or
Eric Engestrom46d68832019-04-24 13:16:57 +0100[diff] [blame]243<code>/usr/lib64</code>. Set <code>-D dri-drivers-path</code> to the directory
Andreas Bollb534c392012-10-05 23:14:10 +0200[diff] [blame]244where your Linux distribution installs DRI drivers. To find your system's DRI
245driver directory, try executing <code>find /usr -type d -name dri</code>. For
246example, if the <code>find</code> command listed <code>/usr/lib64/dri</code>,
Eric Engestrom46d68832019-04-24 13:16:57 +0100[diff] [blame]247then set <code>-D dri-drivers-path=/usr/lib64/dri</code>.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]248</p>
249<p>
Andreas Bollb534c392012-10-05 23:14:10 +0200[diff] [blame]250After determining the correct values for the install location, configure Mesa
Eric Engestrom46d68832019-04-24 13:16:57 +0100[diff] [blame]251with <code>meson configure --prefix=/usr --libdir=xxx -D dri-drivers-path=xxx</code>
252and then install with <code>sudo ninja install</code>.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]253</p>
254<br>
255<br>
256
257
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]258<h1 id="part3">3. Runtime / Rendering Problems</h1>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]259
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]260<h2>3.1 Rendering is slow / why isn't my graphics hardware being used?</h2>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]261<p>
Andreas Bollb534c392012-10-05 23:14:10 +0200[diff] [blame]262If Mesa can't use its hardware accelerated drivers it falls back on one of its software renderers.
263(eg. classic swrast, softpipe or llvmpipe)
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]264</p>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]265<p>
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]266You can run the <code>glxinfo</code> program to learn about your OpenGL
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]267library.
Andreas Bollb534c392012-10-05 23:14:10 +0200[diff] [blame]268Look for the <code>OpenGL vendor</code> and <code>OpenGL renderer</code> values.
269That will identify who's OpenGL library with which driver you're using and what sort of
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]270hardware it has detected.
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]271</p>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]272<p>
Andreas Bollb534c392012-10-05 23:14:10 +0200[diff] [blame]273If you're using a hardware accelerated driver you want <code>direct rendering: Yes</code>.
274</p>
275<p>
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]276If your DRI-based driver isn't working, go to the
Eric Engestrom30cf9ff2017-02-09 02:10:17 +0000[diff] [blame]277<a href="https://dri.freedesktop.org/">DRI website</a> for trouble-shooting information.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]278</p>
279
280
281<h2>3.2 I'm seeing errors in depth (Z) buffering. Why?</h2>
282<p>
283Make sure the ratio of the far to near clipping planes isn't too great.
284Look
Eric Engestrom30cf9ff2017-02-09 02:10:17 +0000[diff] [blame]285<a href="https://www.opengl.org/resources/faq/technical/depthbuffer.htm#0040">here</a>
Andreas Bolla73c59b2012-09-18 19:31:28 +0200[diff] [blame]286for details.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]287</p>
288<p>
289Mesa uses a 16-bit depth buffer by default which is smaller and faster
290to clear than a 32-bit buffer but not as accurate.
291If you need a deeper you can modify the parameters to
292<code> glXChooseVisual</code> in your code.
293</p>
294
295
296<h2>3.3 Why Isn't depth buffering working at all?</h2>
297<p>
298Be sure you're requesting a depth buffered-visual. If you set the MESA_DEBUG
299environment variable it will warn you about trying to enable depth testing
300when you don't have a depth buffer.
301</p>
302<p>Specifically, make sure <code>glutInitDisplayMode</code> is being called
303with <code>GLUT_DEPTH</code> or <code>glXChooseVisual</code> is being
304called with a non-zero value for GLX_DEPTH_SIZE.
305</p>
306<p>This discussion applies to stencil buffers, accumulation buffers and
307alpha channels too.
308</p>
309
310
311<h2>3.4 Why does glGetString() always return NULL?</h2>
312<p>
313Be sure you have an active/current OpenGL rendering context before
314calling glGetString.
315</p>
316
317
318<h2>3.5 GL_POINTS and GL_LINES don't touch the right pixels</h2>
319<p>
320If you're trying to draw a filled region by using GL_POINTS or GL_LINES
321and seeing holes or gaps it's because of a float-to-int rounding problem.
322But this is not a bug.
323See Appendix H of the OpenGL Programming Guide - "OpenGL Correctness Tips".
324Basically, applying a translation of (0.375, 0.375, 0.0) to your coordinates
325will fix the problem.
326</p>
327
328<br>
329<br>
330
331
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]332<h1 id="part4">4. Developer Questions</h1>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]333
Andreas Bollcc418882012-06-12 09:05:33 +0200[diff] [blame]334<h2>4.1 How can I contribute?</h2>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]335<p>
Andreas Boll5abb1f82012-09-19 18:22:37 +0200[diff] [blame]336First, join the <a href="lists.html">mesa-dev mailing list</a>.
Brian Pauld5299bf2006-08-21 14:26:06 +0000[diff] [blame]337That's where Mesa development is discussed.
Dan Nicholsonf71032b2007-12-14 09:59:16 -0800[diff] [blame]338</p>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]339<p>
Eric Engestrom30cf9ff2017-02-09 02:10:17 +0000[diff] [blame]340The <a href="https://www.opengl.org/documentation">
Nathan Kidd0691b372014-01-03 16:44:00 -0700[diff] [blame]341OpenGL Specification</a> is the bible for OpenGL implementation work.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]342You should read it.
343</p>
344<p>Most of the Mesa development work involves implementing new OpenGL
345extensions, writing hardware drivers (for the DRI), and code optimization.
346</p>
347
348<h2>4.2 How do I write a new device driver?</h2>
349<p>
350Unfortunately, writing a device driver isn't easy.
351It requires detailed understanding of OpenGL, the Mesa code, and your
352target hardware/operating system.
3533D graphics are not simple.
354</p>
355<p>
356The best way to get started is to use an existing driver as your starting
357point.
Andreas Bollb534c392012-10-05 23:14:10 +0200[diff] [blame]358For a classic hardware driver, the i965 driver is a good example.
359For a Gallium3D hardware driver, the r300g, r600g and the i915g are good examples.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]360</p>
361<p>The DRI website has more information about writing hardware drivers.
362The process isn't well document because the Mesa driver interface changes
Nathan Kidd0691b372014-01-03 16:44:00 -0700[diff] [blame]363over time, and we seldom have spare time for writing documentation.
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]364That being said, many people have managed to figure out the process.
365</p>
366<p>
367Joining the appropriate mailing lists and asking questions (and searching
368the archives) is a good way to get information.
369</p>
370
371
Brian Paul0c656042006-06-08 19:59:41 +0000[diff] [blame]372<h2>4.3 Why isn't GL_EXT_texture_compression_s3tc implemented in Mesa?</h2>
Brian Paulfc528e22003-12-31 20:59:51 +0000[diff] [blame]373<p>
Stuart Youngc95dd962018-09-20 17:12:43 +1000[diff] [blame]374Oh but it is! Prior to 2nd October 2017, the Mesa project did not include s3tc
375support due to intellectual property (IP) and/or patent issues around the s3tc
376algorithm.
Brian Paulfc528e22003-12-31 20:59:51 +0000[diff] [blame]377</p>
378<p>
Stuart Youngc95dd962018-09-20 17:12:43 +1000[diff] [blame]379As of Mesa 17.3.0, Mesa now officially supports s3tc, as the patent has expired.
380</p>
381<p>
382In versions prior to this, a 3rd party <a href="https://dri.freedesktop.org/wiki/S3TC">
383plug-in library</a> was required.
Brian Paulfc528e22003-12-31 20:59:51 +0000[diff] [blame]384</p>
385
Andreas Bollb5da52a2012-09-18 18:57:02 +0200[diff] [blame]386</div>
Brian Paul0b27ace2003-03-08 17:38:57 +0000[diff] [blame]387</body>
388</html>