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Andreas Boll	ecd5c7c	2012-06-12 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">
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Erik Faye-Lund	269474b	2019-05-06 12:57:15 +0200	[diff] [blame]	5	<title>Frequently Asked Questions</title>
Andreas Boll	ecd5c7c	2012-06-12 09:05:03 +0200	[diff] [blame]	6	<link rel="stylesheet" type="text/css" href="mesa.css">
				7	</head>
				8	<body>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	9
Andreas Boll	b5da52a	2012-09-18 18:57:02 +0200	[diff] [blame]	10	<div class="header">
Erik Faye-Lund	ecdab0d	2019-05-06 13:26:47 +0200	[diff] [blame]	11	The Mesa 3D Graphics Library
Andreas Boll	b5da52a	2012-09-18 18:57:02 +0200	[diff] [blame]	12	</div>
				13
				14	<iframe src="contents.html"></iframe>
				15	<div class="content">
				16
Erik Faye-Lund	269474b	2019-05-06 12:57:15 +0200	[diff] [blame]	17	<h1>Frequently Asked Questions</h1>
Stuart Young	c95dd96	2018-09-20 17:12:43 +1000	[diff] [blame]	18	Last updated: 19 September 2018
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	19
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	20	<h2>Index</h2>
Erik Faye-Lund	da4994f	2019-04-18 13:44:10 +0200	[diff] [blame]	21	<ol>
				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>
				26	</ol>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	27
Erik Faye-Lund	269474b	2019-05-06 12:57:15 +0200	[diff] [blame]	28	<h2 id="part1">1. High-level Questions and Answers</h2>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	29
Erik Faye-Lund	269474b	2019-05-06 12:57:15 +0200	[diff] [blame]	30	<h3>1.1 What is Mesa?</h3>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	31	<p>
Andreas Boll	cc41888	2012-06-12 09:05:33 +0200	[diff] [blame]	32	Mesa is an open-source implementation of the OpenGL specification.
Brian Paul	a376e33	2003-03-30 16:54:36 +0000	[diff] [blame]	33	OpenGL is a programming library for writing interactive 3D applications.
Eric Engestrom	30cf9ff	2017-02-09 02:10:17 +0000	[diff] [blame]	34	See the <a href="https://www.opengl.org/">OpenGL website</a> for more
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	35	information.
				36	</p>
				37	<p>
Andreas Boll	5abb1f8	2012-09-19 18:22:37 +0200	[diff] [blame]	38	Mesa 9.x supports the OpenGL 3.1 specification.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	39	</p>
				40
				41
				42	<h2>1.2 Does Mesa support/use graphics hardware?</h2>
				43	<p>
Brian Paul	7e4cc1c	2005-10-24 23:33:27 +0000	[diff] [blame]	44	Yes. Specifically, Mesa serves as the OpenGL core for the open-source DRI
Andreas Boll	8504f18	2012-09-20 16:23:15 +0200	[diff] [blame]	45	drivers for X.org.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	46	</p>
Andreas Boll	8504f18	2012-09-20 16:23:15 +0200	[diff] [blame]	47	<ul>
Eric Engestrom	30cf9ff	2017-02-09 02:10:17 +0000	[diff] [blame]	48	<li>See the <a href="https://dri.freedesktop.org/">DRI website</a>
Andreas Boll	8504f18	2012-09-20 16:23:15 +0200	[diff] [blame]	49	for more information.</li>
Eric Engestrom	771f6db	2016-07-06 17:09:15 +0100	[diff] [blame]	50	<li>See <a href="https://01.org/linuxgraphics">01.org</a>
Andreas Boll	8504f18	2012-09-20 16:23:15 +0200	[diff] [blame]	51	for more information about Intel drivers.</li>
Eric Engestrom	30cf9ff	2017-02-09 02:10:17 +0000	[diff] [blame]	52	<li>See <a href="https://nouveau.freedesktop.org">nouveau.freedesktop.org</a>
Andreas Boll	8504f18	2012-09-20 16:23:15 +0200	[diff] [blame]	53	for more information about Nouveau drivers.</li>
Eric Engestrom	30cf9ff	2017-02-09 02:10:17 +0000	[diff] [blame]	54	<li>See <a href="https://www.x.org/wiki/RadeonFeature">www.x.org/wiki/RadeonFeature</a>
Andreas Boll	8504f18	2012-09-20 16:23:15 +0200	[diff] [blame]	55	for more information about Radeon drivers.</li>
				56	</ul>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	57
Brian Paul	65b7905	2004-11-22 17:49:15 +0000	[diff] [blame]	58	<h2>1.3 What purpose does Mesa serve today?</h2>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	59	<p>
Brian Paul	a376e33	2003-03-30 16:54:36 +0000	[diff] [blame]	60	Hardware-accelerated OpenGL implementations are available for most popular
				61	operating systems today.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	62	Still, Mesa serves at least these purposes:
				63	</p>
				64	<ul>
Andreas Boll	8504f18	2012-09-20 16:23:15 +0200	[diff] [blame]	65	<li>Mesa is used as the core of the open-source X.org DRI
Brian Paul	7e4cc1c	2005-10-24 23:33:27 +0000	[diff] [blame]	66	hardware drivers.
Brian Paul	a376e33	2003-03-30 16:54:36 +0000	[diff] [blame]	67	</li>
				68	<li>Mesa is quite portable and allows OpenGL to be used on systems
				69	that have no other OpenGL solution.
				70	</li>
				71	<li>Software rendering with Mesa serves as a reference for validating the
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	72	hardware drivers.
Brian Paul	a376e33	2003-03-30 16:54:36 +0000	[diff] [blame]	73	</li>
				74	<li>A software implementation of OpenGL is useful for experimentation,
				75	such as testing new rendering techniques.
				76	</li>
				77	<li>Mesa can render images with deep color channels: 16-bit integer
				78	and 32-bit floating point color channels are supported.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	79	This capability is only now appearing in hardware.
Brian Paul	a376e33	2003-03-30 16:54:36 +0000	[diff] [blame]	80	</li>
				81	<li>Mesa's internal limits (max lights, clip planes, texture size, etc) can be
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	82	changed for special needs (hardware limits are hard to overcome).
Brian Paul	a376e33	2003-03-30 16:54:36 +0000	[diff] [blame]	83	</li>
				84	</ul>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	85
Brian Paul	65b7905	2004-11-22 17:49:15 +0000	[diff] [blame]	86
Andreas Boll	5abb1f8	2012-09-19 18:22:37 +0200	[diff] [blame]	87	<h2>1.4 What's the difference between "Stand-Alone" Mesa and the DRI drivers?</h2>
Brian Paul	65b7905	2004-11-22 17:49:15 +0000	[diff] [blame]	88	<p>
				89	<em>Stand-alone Mesa</em> is the original incarnation of Mesa.
Brian Paul	7e4cc1c	2005-10-24 23:33:27 +0000	[diff] [blame]	90	On systems running the X Window System it does all its rendering through
				91	the Xlib API:
Andreas Boll	df2be22	2012-06-12 09:05:22 +0200	[diff] [blame]	92	</p>
Brian Paul	65b7905	2004-11-22 17:49:15 +0000	[diff] [blame]	93	<ul>
				94	<li>The GLX API is supported, but it's really just an emulation of the
				95	real thing.
				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, libGL.so, contains everything (the programming API,
				100	the GLX functions and all the rendering code).
				101	</ul>
Brian Paul	65b7905	2004-11-22 17:49:15 +0000	[diff] [blame]	102	<p>
				103	Alternately, Mesa acts as the core for a number of OpenGL hardware drivers
				104	within the DRI (Direct Rendering Infrastructure):
				105	<ul>
				106	<li>The libGL.so library provides the GL and GLX API functions, a GLX
				107	protocol encoder, and a device driver loader.
				108	<li>The device driver modules (such as r200_dri.so) contain a built-in
				109	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.
				114	</ul>
				115
				116
				117
				118	<h2>1.5 How do I upgrade my DRI installation to use a new Mesa release?</h2>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	119	<p>
Brian Paul	7e4cc1c	2005-10-24 23:33:27 +0000	[diff] [blame]	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>.
Brian Paul	824a4fc	2003-08-06 19:05:26 +0000	[diff] [blame]	124	</p>
				125
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	126
Brian Paul	65b7905	2004-11-22 17:49:15 +0000	[diff] [blame]	127	<h2>1.6 Are there other open-source implementations of OpenGL?</h2>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	128	<p>
Andreas Boll	a73c59b	2012-09-18 19:31:28 +0200	[diff] [blame]	129	Yes, SGI's <a href="http://oss.sgi.com/projects/ogl-sample/index.html">
Nathan Kidd	0691b37	2014-01-03 16:44:00 -0700	[diff] [blame]	130	OpenGL Sample Implementation (SI)</a> is available.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	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.
				134	</p>
Brian Paul	186d4d8	2004-04-27 12:55:08 +0000	[diff] [blame]	135
				136	<p>
Eric Engestrom	30cf9ff	2017-02-09 02:10:17 +0000	[diff] [blame]	137	<a href="https://sourceforge.net/projects/ogl-es/">Vincent</a> is
Brian Paul	186d4d8	2004-04-27 12:55:08 +0000	[diff] [blame]	138	an open-source implementation of OpenGL ES for mobile devices.
				139
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	140	<p>
Andreas Boll	a73c59b	2012-09-18 19:31:28 +0200	[diff] [blame]	141	<a href="http://www.dsbox.com/minigl.html">miniGL</a>
Brian Paul	7df4f95	2003-11-25 21:13:26 +0000	[diff] [blame]	142	is a subset of OpenGL for PalmOS devices.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	143
Brian Paul	7df4f95	2003-11-25 21:13:26 +0000	[diff] [blame]	144	<p>
Andreas Boll	8504f18	2012-09-20 16:23:15 +0200	[diff] [blame]	145	<a href="http://bellard.org/TinyGL/">TinyGL</a>
Andreas Boll	a73c59b	2012-09-18 19:31:28 +0200	[diff] [blame]	146	is a subset of OpenGL.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	147	</p>
Brian Paul	7df4f95	2003-11-25 21:13:26 +0000	[diff] [blame]	148
				149	<p>
Eric Engestrom	30cf9ff	2017-02-09 02:10:17 +0000	[diff] [blame]	150	<a href="https://sourceforge.net/projects/softgl/">SoftGL</a>
Brian Paul	7df4f95	2003-11-25 21:13:26 +0000	[diff] [blame]	151	is an OpenGL subset for mobile devices.
				152	</p>
				153
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	154	<p>
Andreas Boll	a73c59b	2012-09-18 19:31:28 +0200	[diff] [blame]	155	<a href="http://chromium.sourceforge.net/">Chromium</a>
Brian Paul	acbc1e0	2003-11-26 18:10:31 +0000	[diff] [blame]	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
				158	rendering, etc.
				159	</p>
				160
Brian Paul	acbc1e0	2003-11-26 18:10:31 +0000	[diff] [blame]	161	<p>
Andreas Boll	a73c59b	2012-09-18 19:31:28 +0200	[diff] [blame]	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.
Brian Paul	0c65604	2006-06-08 19:59:41 +0000	[diff] [blame]	164	</p>
				165
				166	<p>
Brian Paul	acbc1e0	2003-11-26 18:10:31 +0000	[diff] [blame]	167	There may be other open OpenGL implementations, but Mesa is the most
				168	popular and feature-complete.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	169	</p>
				170
Brian Paul	65b7905	2004-11-22 17:49:15 +0000	[diff] [blame]	171
Erik Faye-Lund	269474b	2019-05-06 12:57:15 +0200	[diff] [blame]	172	<h2 id="part2">2. Compilation and Installation Problems</h2>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	173
Erik Faye-Lund	269474b	2019-05-06 12:57:15 +0200	[diff] [blame]	174	<h3>2.1 What's the easiest way to install Mesa?</h3>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	175	<p>
Andreas Boll	cc41888	2012-06-12 09:05:33 +0200	[diff] [blame]	176	If you're using a Linux-based system, your distro CD most likely already
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	177	has Mesa packages (like RPM or DEB) which you can easily install.
Andreas Boll	cc41888	2012-06-12 09:05:33 +0200	[diff] [blame]	178	</p>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	179
				180
Erik Faye-Lund	269474b	2019-05-06 12:57:15 +0200	[diff] [blame]	181	<h3>2.2 I get undefined symbols such as bgnpolygon, v3f, etc...</h3>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	182	<p>
Andreas Boll	cc41888	2012-06-12 09:05:33 +0200	[diff] [blame]	183	You're application is written in IRIS GL, not OpenGL.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	184	IRIS GL was the predecessor to OpenGL and is a different thing (almost)
				185	entirely.
				186	Mesa's not the solution.
Andreas Boll	cc41888	2012-06-12 09:05:33 +0200	[diff] [blame]	187	</p>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	188
				189
Erik Faye-Lund	269474b	2019-05-06 12:57:15 +0200	[diff] [blame]	190	<h3>2.3 Where is the GLUT library?</h3>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	191	<p>
Andreas Boll	cc41888	2012-06-12 09:05:33 +0200	[diff] [blame]	192	GLUT (OpenGL Utility Toolkit) is no longer in the separate MesaGLUT-x.y.z.tar.gz file.
José Fonseca	9a7f84d	2011-07-14 17:28:52 +0100	[diff] [blame]	193	If you don't already have GLUT installed, you should grab
				194	<a href="http://freeglut.sourceforge.net/">freeglut</a>.
Andreas Boll	cc41888	2012-06-12 09:05:33 +0200	[diff] [blame]	195	</p>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	196
				197
Erik Faye-Lund	269474b	2019-05-06 12:57:15 +0200	[diff] [blame]	198	<h3>2.4 Where is the GLw library?</h3>
Kenneth Graunke	c548192	2011-08-05 16:59:04 -0700	[diff] [blame]	199	<p>
Eric Engestrom	30cf9ff	2017-02-09 02:10:17 +0000	[diff] [blame]	200	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.
Andreas Boll	cc41888	2012-06-12 09:05:33 +0200	[diff] [blame]	201	</p>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	202
Kenneth Graunke	c548192	2011-08-05 16:59:04 -0700	[diff] [blame]	203
Andreas Boll	cc41888	2012-06-12 09:05:33 +0200	[diff] [blame]	204	<h2>2.5 What's the proper place for the libraries and headers?</h2>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	205	<p>
Andreas Boll	cc41888	2012-06-12 09:05:33 +0200	[diff] [blame]	206	On Linux-based systems you'll want to follow the
Andreas Boll	a73c59b	2012-09-18 19:31:28 +0200	[diff] [blame]	207	<a href="http://oss.sgi.com/projects/ogl-sample/ABI/index.html">Linux ABI</a> standard.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	208	Basically you'll want the following:
				209	</p>
Erik Faye-Lund	b16e593	2019-06-04 15:42:46 +0200	[diff] [blame^]	210	<dl>
				211	<dt><code>/usr/include/GL/gl.h</code></dt>
				212	<dd>the main OpenGL header</dd>
				213	<dt><code>/usr/include/GL/glu.h</code></dt>
				214	<dd>the OpenGL GLU (utility) header</dd>
				215	<dt><code>/usr/include/GL/glx.h</code></dt>
				216	<dd>the OpenGL GLX header</dd>
				217	<dt><code>/usr/include/GL/glext.h</code></dt>
				218	<dd>the OpenGL extensions header</dd>
				219	<dt><code>/usr/include/GL/glxext.h</code></dt>
				220	<dd>the OpenGL GLX extensions header</dd>
				221	<dt><code>/usr/include/GL/osmesa.h</code></dt>
				222	<dd>the Mesa off-screen rendering header</dd>
				223	<dt><code>/usr/lib/libGL.so</code></dt>
				224	<dd>a symlink to <code>libGL.so.1</code></dd>
				225	<dt><code>/usr/lib/libGL.so.1</code></dt>
				226	<dd>a symlink to <code>libGL.so.1.xyz</code></dd>
				227	<dt><code>/usr/lib/libGL.so.xyz</code></dt>
				228	<dd>the actual OpenGL/Mesa library. xyz denotes the
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	229	Mesa version number.
Erik Faye-Lund	b16e593	2019-06-04 15:42:46 +0200	[diff] [blame^]	230	</dd>
				231	</dl>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	232	<p>
Eric Engestrom	46d6883	2019-04-24 13:16:57 +0100	[diff] [blame]	233	When configuring Mesa, there are three meson options that affect the install
Andreas Boll	b534c39	2012-10-05 23:14:10 +0200	[diff] [blame]	234	location that you should take care with: <code>--prefix</code>,
Eric Engestrom	46d6883	2019-04-24 13:16:57 +0100	[diff] [blame]	235	<code>--libdir</code>, and <code>-D dri-drivers-path</code>. To install Mesa
Andreas Boll	b534c39	2012-10-05 23:14:10 +0200	[diff] [blame]	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
Eric Engestrom	46d6883	2019-04-24 13:16:57 +0100	[diff] [blame]	239	<code>/usr/lib64</code>. Set <code>-D dri-drivers-path</code> to the directory
Andreas Boll	b534c39	2012-10-05 23:14:10 +0200	[diff] [blame]	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>,
Eric Engestrom	46d6883	2019-04-24 13:16:57 +0100	[diff] [blame]	243	then set <code>-D dri-drivers-path=/usr/lib64/dri</code>.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	244	</p>
				245	<p>
Andreas Boll	b534c39	2012-10-05 23:14:10 +0200	[diff] [blame]	246	After determining the correct values for the install location, configure Mesa
Eric Engestrom	46d6883	2019-04-24 13:16:57 +0100	[diff] [blame]	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>.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	249	</p>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	250
				251
Erik Faye-Lund	269474b	2019-05-06 12:57:15 +0200	[diff] [blame]	252	<h2 id="part3">3. Runtime / Rendering Problems</h2>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	253
Erik Faye-Lund	269474b	2019-05-06 12:57:15 +0200	[diff] [blame]	254	<h3>3.1 Rendering is slow / why isn't my graphics hardware being used?</h3>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	255	<p>
Andreas Boll	b534c39	2012-10-05 23:14:10 +0200	[diff] [blame]	256	If Mesa can't use its hardware accelerated drivers it falls back on one of its software renderers.
				257	(eg. classic swrast, softpipe or llvmpipe)
Andreas Boll	cc41888	2012-06-12 09:05:33 +0200	[diff] [blame]	258	</p>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	259	<p>
Andreas Boll	cc41888	2012-06-12 09:05:33 +0200	[diff] [blame]	260	You can run the <code>glxinfo</code> program to learn about your OpenGL
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	261	library.
Andreas Boll	b534c39	2012-10-05 23:14:10 +0200	[diff] [blame]	262	Look for the <code>OpenGL vendor</code> and <code>OpenGL renderer</code> values.
				263	That will identify who's OpenGL library with which driver you're using and what sort of
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	264	hardware it has detected.
Andreas Boll	cc41888	2012-06-12 09:05:33 +0200	[diff] [blame]	265	</p>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	266	<p>
Andreas Boll	b534c39	2012-10-05 23:14:10 +0200	[diff] [blame]	267	If you're using a hardware accelerated driver you want <code>direct rendering: Yes</code>.
				268	</p>
				269	<p>
Andreas Boll	cc41888	2012-06-12 09:05:33 +0200	[diff] [blame]	270	If your DRI-based driver isn't working, go to the
Eric Engestrom	30cf9ff	2017-02-09 02:10:17 +0000	[diff] [blame]	271	<a href="https://dri.freedesktop.org/">DRI website</a> for trouble-shooting information.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	272	</p>
				273
				274
Erik Faye-Lund	269474b	2019-05-06 12:57:15 +0200	[diff] [blame]	275	<h3>3.2 I'm seeing errors in depth (Z) buffering. Why?</h3>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	276	<p>
				277	Make sure the ratio of the far to near clipping planes isn't too great.
				278	Look
Eric Engestrom	30cf9ff	2017-02-09 02:10:17 +0000	[diff] [blame]	279	<a href="https://www.opengl.org/resources/faq/technical/depthbuffer.htm#0040">here</a>
Andreas Boll	a73c59b	2012-09-18 19:31:28 +0200	[diff] [blame]	280	for details.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	281	</p>
				282	<p>
				283	Mesa uses a 16-bit depth buffer by default which is smaller and faster
				284	to clear than a 32-bit buffer but not as accurate.
				285	If you need a deeper you can modify the parameters to
Erik Faye-Lund	b2ac758	2019-05-28 13:53:03 +0200	[diff] [blame]	286	<code>glXChooseVisual</code> in your code.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	287	</p>
				288
				289
Erik Faye-Lund	269474b	2019-05-06 12:57:15 +0200	[diff] [blame]	290	<h3>3.3 Why Isn't depth buffering working at all?</h3>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	291	<p>
Erik Faye-Lund	392c083	2019-05-28 13:14:03 +0200	[diff] [blame]	292	Be sure you're requesting a depth buffered-visual. If you set the
				293	<code>MESA_DEBUG</code> environment variable it will warn you about trying
				294	to enable depth testing when you don't have a depth buffer.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	295	</p>
				296	<p>Specifically, make sure <code>glutInitDisplayMode</code> is being called
				297	with <code>GLUT_DEPTH</code> or <code>glXChooseVisual</code> is being
Erik Faye-Lund	392c083	2019-05-28 13:14:03 +0200	[diff] [blame]	298	called with a non-zero value for <code>GLX_DEPTH_SIZE</code>.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	299	</p>
				300	<p>This discussion applies to stencil buffers, accumulation buffers and
				301	alpha channels too.
				302	</p>
				303
				304
Erik Faye-Lund	392c083	2019-05-28 13:14:03 +0200	[diff] [blame]	305	<h3>3.4 Why does <code>glGetString()</code> always return <code>NULL</code>?</h3>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	306	<p>
				307	Be sure you have an active/current OpenGL rendering context before
Erik Faye-Lund	392c083	2019-05-28 13:14:03 +0200	[diff] [blame]	308	calling <code>glGetString</code>.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	309	</p>
				310
				311
Erik Faye-Lund	392c083	2019-05-28 13:14:03 +0200	[diff] [blame]	312	<h3>3.5 <code>GL_POINTS</code> and <code>GL_LINES</code> don't touch the
				313	right pixels</h3>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	314	<p>
Erik Faye-Lund	392c083	2019-05-28 13:14:03 +0200	[diff] [blame]	315	If you're trying to draw a filled region by using <code>GL_POINTS</code> or
				316	<code>GL_LINES</code> and seeing holes or gaps it's because of a float-to-int
				317	rounding problem. But this is not a bug. See Appendix H of the OpenGL
				318	Programming Guide - "OpenGL Correctness Tips". Basically, applying a
				319	translation of (0.375, 0.375, 0.0) to your coordinates will fix the problem.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	320	</p>
				321
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	322
Erik Faye-Lund	269474b	2019-05-06 12:57:15 +0200	[diff] [blame]	323	<h2 id="part4">4. Developer Questions</h2>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	324
Erik Faye-Lund	269474b	2019-05-06 12:57:15 +0200	[diff] [blame]	325	<h3>4.1 How can I contribute?</h3>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	326	<p>
Andreas Boll	5abb1f8	2012-09-19 18:22:37 +0200	[diff] [blame]	327	First, join the <a href="lists.html">mesa-dev mailing list</a>.
Brian Paul	d5299bf	2006-08-21 14:26:06 +0000	[diff] [blame]	328	That's where Mesa development is discussed.
Dan Nicholson	f71032b	2007-12-14 09:59:16 -0800	[diff] [blame]	329	</p>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	330	<p>
Eric Engestrom	30cf9ff	2017-02-09 02:10:17 +0000	[diff] [blame]	331	The <a href="https://www.opengl.org/documentation">
Nathan Kidd	0691b37	2014-01-03 16:44:00 -0700	[diff] [blame]	332	OpenGL Specification</a> is the bible for OpenGL implementation work.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	333	You should read it.
				334	</p>
				335	<p>Most of the Mesa development work involves implementing new OpenGL
				336	extensions, writing hardware drivers (for the DRI), and code optimization.
				337	</p>
				338
Erik Faye-Lund	269474b	2019-05-06 12:57:15 +0200	[diff] [blame]	339	<h3>4.2 How do I write a new device driver?</h3>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	340	<p>
				341	Unfortunately, writing a device driver isn't easy.
				342	It requires detailed understanding of OpenGL, the Mesa code, and your
				343	target hardware/operating system.
				344	3D graphics are not simple.
				345	</p>
				346	<p>
				347	The best way to get started is to use an existing driver as your starting
				348	point.
Andreas Boll	b534c39	2012-10-05 23:14:10 +0200	[diff] [blame]	349	For a classic hardware driver, the i965 driver is a good example.
				350	For a Gallium3D hardware driver, the r300g, r600g and the i915g are good examples.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	351	</p>
				352	<p>The DRI website has more information about writing hardware drivers.
				353	The process isn't well document because the Mesa driver interface changes
Nathan Kidd	0691b37	2014-01-03 16:44:00 -0700	[diff] [blame]	354	over time, and we seldom have spare time for writing documentation.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	355	That being said, many people have managed to figure out the process.
				356	</p>
				357	<p>
				358	Joining the appropriate mailing lists and asking questions (and searching
				359	the archives) is a good way to get information.
				360	</p>
				361
				362
Erik Faye-Lund	392c083	2019-05-28 13:14:03 +0200	[diff] [blame]	363	<h3>4.3 Why isn't <code>GL_EXT_texture_compression_s3tc</code> implemented in
				364	Mesa?</h3>
Brian Paul	fc528e2	2003-12-31 20:59:51 +0000	[diff] [blame]	365	<p>
Stuart Young	c95dd96	2018-09-20 17:12:43 +1000	[diff] [blame]	366	Oh but it is! Prior to 2nd October 2017, the Mesa project did not include s3tc
				367	support due to intellectual property (IP) and/or patent issues around the s3tc
				368	algorithm.
Brian Paul	fc528e2	2003-12-31 20:59:51 +0000	[diff] [blame]	369	</p>
				370	<p>
Stuart Young	c95dd96	2018-09-20 17:12:43 +1000	[diff] [blame]	371	As of Mesa 17.3.0, Mesa now officially supports s3tc, as the patent has expired.
				372	</p>
				373	<p>
				374	In versions prior to this, a 3rd party <a href="https://dri.freedesktop.org/wiki/S3TC">
				375	plug-in library</a> was required.
Brian Paul	fc528e2	2003-12-31 20:59:51 +0000	[diff] [blame]	376	</p>
				377
Andreas Boll	b5da52a	2012-09-18 18:57:02 +0200	[diff] [blame]	378	</div>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	379	</body>
				380	</html>