Gitiles
Code Review Sign In
gerrit-public.fairphone.software / platform / external / mesa3d / 51ab599ddb213d6b846f333bbf03d5f6dde4831f / . / docs / egl.html
blob: 305e5f6eab71c5222ef17566257af16d0b6fa263 [file] [log] [blame]
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]1<html>
2
3<title>Mesa EGL</title>
4
5<head><link rel="stylesheet" type="text/css" href="mesa.css"></head>
6
7<body>
8
9<h1>Mesa EGL</h1>
10
11<p>The current version of EGL in Mesa implements EGL 1.4. More information
12about EGL can be found at
Brian Paulaeff9f92010-01-21 08:13:32 -0700[diff] [blame]13<a href="http://www.khronos.org/egl/" target="_parent">
14http://www.khronos.org/egl/</a>.</p>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]15
16<p>The Mesa's implementation of EGL uses a driver architecture. The main
17library (<code>libEGL</code>) is window system neutral. It provides the EGL
18API entry points and helper functions for use by the drivers. Drivers are
19dynamically loaded by the main library and most of the EGL API calls are
20directly dispatched to the drivers.</p>
21
22<p>The driver in use decides the window system to support. For drivers that
23support hardware rendering, there are usually multiple drivers supporting the
24same window system. Each one of of them supports a certain range of graphics
25cards.</p>
26
27<h2>Build EGL</h2>
28
29<ol>
30<li>
31<p>Run <code>configure</code> with the desired state trackers and and enable
32the Gallium driver for your hardware. For example</p>
33
34<pre>
Chia-I Wua6342af2010-01-26 10:54:45 +0800[diff] [blame]35 $ ./configure --with-state-trackers=egl,es,vega --enable-gallium-{swrast,intel}
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]36</pre>
37
Chia-I Wu3c967a92010-01-22 16:31:43 +0800[diff] [blame]38<p>The main library will be enabled by default. The <code>egl</code> state
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]39tracker is needed by a number of EGL drivers. EGL drivers will be covered
40later. The <a href="opengles.html">es state tracker</a> provides OpenGL ES 1.x
41and 2.x and the <a href="openvg.html">vega state tracker</a> provides OpenVG
421.x.</p>
43</li>
44
45<li>Build and install Mesa as usual.</li>
46</ol>
47
48<p>In the given example, it will build and install <code>libEGL</code>,
49<code>libGLESv1_CM</code>, <code>libGLESv2</code>, <code>libOpenVG</code>, and
50one or more EGL drivers.</p>
51
52<h3>Configure Options</h3>
53
54<p>There are several options that control the build of EGL at configuration
55time</p>
56
57<ul>
58<li><code>--enable-egl</code>
59
60<p>By default, EGL is enabled. When disabled, the main library and the drivers
61will not be built.</p>
62
63</li>
64
Chia-I Wua6342af2010-01-26 10:54:45 +0800[diff] [blame]65<li><code>--with-egl-driver-dir</code>
66
67<p>The directory EGL drivers should be installed to. If not specified, EGL
68drivers will be installed to <code>${libdir}/egl</code>.</p>
69
70</li>
71
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]72<li><code>--with-egl-displays</code>
73
74<p>List the window system(s) to support. It is by default <code>x11</code>,
75which supports the X Window System. Its argument is a comma separated string
76like, for example, <code>--with-egl-displays=x11,kms</code>. Because an EGL
77driver decides which window system to support, this example will enable two
78(sets of) EGL drivers. One supports the X window system and the other supports
79bare KMS (kernel modesetting).</p>
80
81</li>
82
83<li><code>--with-state-trackers</code>
84
85<p>The argument is a comma separated string. It is usually used to specify the
86rendering APIs, like OpenGL ES or OpenVG, to build. But it should be noted
Chia-I Wu3c967a92010-01-22 16:31:43 +0800[diff] [blame]87that a number of EGL drivers depend on the <code>egl</code> state tracker.
88They will <em>not</em> be built without the <code>egl</code> state tracker.</p>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]89
90</li>
Chia-I Wua1306f42010-01-22 15:51:51 +0800[diff] [blame]91
92<li><code>--enable-gallium-swrast</code>
93
94<p>This option is not specific to EGL. But if there is no driver for your
95hardware, or you are experiencing problems with the hardware driver, you can
96enable the swrast DRM driver. It is a dummy driver and EGL will fallback to
97software rendering automatically.</p>
98
99</li>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]100</ul>
101
102<h3>OpenGL</h3>
103
104<p>The OpenGL state tracker is not built in the above example. It should be
105noted that the classic <code>libGL</code> is not a state tracker and cannot be
106used with EGL (unless the EGL driver in use is <code>egl_glx</code>). To build
107the OpenGL state tracker, one may append <code>glx</code> to
108<code>--with-state-trackers</code> and manually build
109<code>src/gallium/winsys/xlib/</code>.</p>
110
111<h2>Use EGL</h2>
112
113<p> The demos for OpenGL ES and OpenVG can be found in <code>progs/es1/</code>,
114<code>progs/es2/</code> and <code>progs/openvg/</code>. You can use them to
115test your build. For example,</p>
116
117<pre>
118 $ cd progs/es1/xegl
119 $ make
120 $ ./torus
121</pre>
122
123<h3>Environment Variables</h3>
124
125<p>There are several environment variables that control the behavior of EGL at
126runtime</p>
127
128<ul>
129<li><code>EGL_DRIVER</code>
130
131<p>This variable forces the specified EGL driver to be loaded. It comes in
132handy when one wants to test a specific driver.</p>
133
134</li>
135
136<li><code>EGL_DISPLAY</code>
137
138<p>When <code>EGL_DRIVER</code> is not set, the main library loads <em>all</em>
139EGL drivers that support a certain window system. <code>EGL_DISPLAY</code> can
140be used to specify the window system and the valid values are, for example,
141<code>x11</code> or <code>kms</code>. When the variable is not set, the main
142library defaults the value to the first window system listed in
143<code>--with-egl-displays</code> at configuration time.
144
145</li>
146
147<li><code>EGL_LOG_LEVEL</code>
148
149<p>This changes the log level of the main library and the drivers. The valid
150values are: <code>debug</code>, <code>info</code>, <code>warning</code>, and
151<code>fatal</code>.</p>
152
153</li>
154
155<li><code>EGL_SOFTWARE</code>
156
157<p>For drivers that support both hardware and software rendering, setting this
158variable to true forces the use of software rendering.</p>
159
160</li>
161</ul>
162
163<h2>EGL Drivers</h2>
164
165<p>There are two categories of EGL drivers: Gallium and classic.</p>
166
167<p>Gallium EGL drivers supports all rendering APIs specified in EGL 1.4. The
168support for optional EGL functions and EGL extensions is usually more complete
Chia-I Wu3c967a92010-01-22 16:31:43 +0800[diff] [blame]169than the classic ones. These drivers depend on the <code>egl</code> state
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]170tracker to build. The available drivers are</p>
171
172<ul>
173<li><code>egl_&lt;dpy&gt;_i915</code></li>
174<li><code>egl_&lt;dpy&gt;_i965</code></li>
175<li><code>egl_&lt;dpy&gt;_radeon</code></li>
176<li><code>egl_&lt;dpy&gt;_nouveau</code></li>
Chia-I Wua1306f42010-01-22 15:51:51 +0800[diff] [blame]177<li><code>egl_&lt;dpy&gt;_swrast</code></li>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]178<li><code>egl_&lt;dpy&gt;_vmwgfx</code></li>
179</ul>
180
181<p><code>&lt;dpy&gt;</code> is given by <code>--with-egl-displays</code> at
182configuration time. There will be one EGL driver for each combination of the
183displays listed and the hardware drivers enabled.</p>
184
185<p>Classic EGL drivers, on the other hand, supports only OpenGL as its
186rendering API. They can be found under <code>src/egl/drivers/</code>. There
187are 3 of them</p>
188
189<ul>
190<li><code>egl_glx</code>
191
192<p>This driver provides a wrapper to GLX. It uses exclusively GLX to implement
193the EGL API. It supports both direct and indirect rendering when the GLX does.
194It is accelerated when the GLX is. As such, it cannot provide functions that
195is not available in GLX or GLX extensions.</p>
196</li>
197
198<li><code>egl_xdri</code>
199
200<p>This driver supports the X Window System as its window system. It functions
Chia-I Wu29732f92010-01-22 15:05:31 +0800[diff] [blame]201as a DRI driver loader and can load DRI/DRI2/DRISW drivers. Unlike
202<code>egl_glx</code>, it has no dependency on <code>libGL</code>. It talks to
203the X server directly using DRI or DRI2 protocols. It also talks minimal GLX
204protocol for things like available visuals or fbconfigs. With direct access to
205the DRI drivers, it has the potential to support more EGL functions that are
206not possible with <code>egl_glx</code>.</p>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]207
208</li>
209<li><code>egl_dri</code>
210
211<p>This driver lacks maintenance and does <em>not</em> build. It is similiar
212to <code>egl_xdri</code> in that it functions as a DRI driver loader. But
213unlike <code>egl_xdri</code>, it supports Linux framebuffer devices as its
214window system and supports EGL_MESA_screen_surface extension. It loads only
215DRI1 drivers. As DRI1 drivers is phasing out, it might be better to rewrite
216the driver to support KMS and DRI2.</p>
217
218</li>
219</ul>
220
221<p>To use the classic drivers, one must manually set <code>EGL_DRIVER</code> at
222runtime.</p>
223
224<h2>Developers</h2>
225
226The sources of the main library and the classic drivers can be found at
Chia-I Wu3c967a92010-01-22 16:31:43 +0800[diff] [blame]227<code>src/egl/</code>. The sources of the <code>egl</code> state tracker can
228be found at <code>src/gallium/state_trackers/egl/</code>.
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]229
230<h3>TODOs</h3>
231
232<ul>
233<li>Thread safety</li>
234<li>Pass the conformance tests</li>
235<li>Better automatic driver selection: <code>EGL_DISPLAY</code> loads all
236drivers and might eat too much memory.</li>
Chia-I Wua6342af2010-01-26 10:54:45 +0800[diff] [blame]237<li>Stop using <code>glxinit.c</code> and sources from <code>src/glx/x11/</code></li>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]238
239</ul>
240
241</body>
242</html>