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gerrit-public.fairphone.software / platform / external / mesa3d / 5564c361b5cc1f5ec4be3622d7f9be601e3c268a / . / docs / egl.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 EGL</title>
6 <link rel="stylesheet" type="text/css" href="mesa.css">
7</head>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]8<body>
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
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]17<h1>Mesa EGL</h1>
18
19<p>The current version of EGL in Mesa implements EGL 1.4. More information
20about EGL can be found at
Andreas Bolla73c59b2012-09-18 19:31:28 +0200[diff] [blame]21<a href="http://www.khronos.org/egl/">
Brian Paulaeff9f92010-01-21 08:13:32 -0700[diff] [blame]22http://www.khronos.org/egl/</a>.</p>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]23
24<p>The Mesa's implementation of EGL uses a driver architecture. The main
25library (<code>libEGL</code>) is window system neutral. It provides the EGL
26API entry points and helper functions for use by the drivers. Drivers are
27dynamically loaded by the main library and most of the EGL API calls are
28directly dispatched to the drivers.</p>
29
Chia-I Wu65e8f812010-12-25 02:45:13 +0800[diff] [blame]30<p>The driver in use decides the window system to support.</p>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]31
32<h2>Build EGL</h2>
33
34<ol>
35<li>
Chia-I Wu3418f742010-11-02 23:55:56 +0800[diff] [blame]36<p>Run <code>configure</code> with the desired client APIs and enable
37the driver for your hardware. For example</p>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]38
39<pre>
Chia-I Wu8eea0502011-06-20 11:14:56 +0900[diff] [blame]40 $ ./configure --enable-gles1 --enable-gles2 \
41 --with-dri-drivers=... \
42 --with-gallium-drivers=...
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]43</pre>
44
Chia-I Wu8eea0502011-06-20 11:14:56 +0900[diff] [blame]45<p>The main library and OpenGL is enabled by default. The first two options
46above enables <a href="opengles.html">OpenGL ES 1.x and 2.x</a>. The last two
47options enables the listed classic and and Gallium drivers respectively.</p>
Chia-I Wuc6320c52010-10-28 17:25:07 +0800[diff] [blame]48
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]49</li>
50
51<li>Build and install Mesa as usual.</li>
52</ol>
53
54<p>In the given example, it will build and install <code>libEGL</code>,
Chia-I Wu8eea0502011-06-20 11:14:56 +0900[diff] [blame]55<code>libGL</code>, <code>libGLESv1_CM</code>, <code>libGLESv2</code>, and one
56or more EGL drivers.</p>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]57
58<h3>Configure Options</h3>
59
60<p>There are several options that control the build of EGL at configuration
61time</p>
62
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]63<dl>
64<dt><code>--enable-egl</code></dt>
65<dd>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]66
67<p>By default, EGL is enabled. When disabled, the main library and the drivers
68will not be built.</p>
69
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]70</dd>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]71
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]72<dt><code>--with-egl-driver-dir</code></dt>
73<dd>
Chia-I Wua6342af2010-01-26 10:54:45 +0800[diff] [blame]74
75<p>The directory EGL drivers should be installed to. If not specified, EGL
76drivers will be installed to <code>${libdir}/egl</code>.</p>
77
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]78</dd>
Chia-I Wua6342af2010-01-26 10:54:45 +0800[diff] [blame]79
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]80<dt><code>--with-egl-platforms</code></dt>
81<dd>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]82
Chia-I Wub365b152010-07-03 17:18:40 +0800[diff] [blame]83<p>List the platforms (window systems) to support. Its argument is a comma
Nathan Kidd0691b372014-01-03 16:44:00 -0700[diff] [blame]84separated string such as <code>--with-egl-platforms=x11,drm</code>. It decides
Chia-I Wub365b152010-07-03 17:18:40 +0800[diff] [blame]85the platforms a driver may support. The first listed platform is also used by
86the main library to decide the native platform: the platform the EGL native
87types such as <code>EGLNativeDisplayType</code> or
88<code>EGLNativeWindowType</code> defined for.</p>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]89
Chia-I Wue7424d72010-09-19 16:54:39 +0800[diff] [blame]90<p>The available platforms are <code>x11</code>, <code>drm</code>,
Chia-I Wuda39d5d2010-06-17 16:07:46 +0800[diff] [blame]91<code>fbdev</code>, and <code>gdi</code>. The <code>gdi</code> platform can
Chia-I Wu3418f742010-11-02 23:55:56 +0800[diff] [blame]92only be built with SCons. Unless for special needs, the build system should
93select the right platforms automatically.</p>
Chia-I Wu2e3c4e42010-05-07 14:13:08 +0800[diff] [blame]94
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]95</dd>
Chia-I Wu2e3c4e42010-05-07 14:13:08 +0800[diff] [blame]96
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]97<dt><code>--enable-gles1</code></dt>
98<dt><code>--enable-gles2</code></dt>
99<dd>
Chia-I Wu2e3c4e42010-05-07 14:13:08 +0800[diff] [blame]100
Chia-I Wu65e8f812010-12-25 02:45:13 +0800[diff] [blame]101<p>These options enable OpenGL ES support in OpenGL. The result is one big
102internal library that supports multiple APIs.</p>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]103
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]104</dd>
Chia-I Wua1306f42010-01-22 15:51:51 +0800[diff] [blame]105
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]106<dt><code>--enable-shared-glapi</code></dt>
107<dd>
Chia-I Wuc6320c52010-10-28 17:25:07 +0800[diff] [blame]108
Chia-I Wu8eea0502011-06-20 11:14:56 +0900[diff] [blame]109<p>By default, <code>libGL</code> has its own copy of <code>libglapi</code>.
110This options makes <code>libGL</code> use the shared <code>libglapi</code>. This
111is required if applications mix OpenGL and OpenGL ES.</p>
Chia-I Wuc6320c52010-10-28 17:25:07 +0800[diff] [blame]112
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]113</dd>
Chia-I Wuc6320c52010-10-28 17:25:07 +0800[diff] [blame]114
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]115<dt><code>--enable-openvg</code></dt>
116<dd>
Chia-I Wu3418f742010-11-02 23:55:56 +0800[diff] [blame]117
Chia-I Wu8eea0502011-06-20 11:14:56 +0900[diff] [blame]118<p>OpenVG must be explicitly enabled by this option.</p>
Chia-I Wu3418f742010-11-02 23:55:56 +0800[diff] [blame]119
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]120</dd>
Chia-I Wu3418f742010-11-02 23:55:56 +0800[diff] [blame]121
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]122</dl>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]123
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]124<h2>Use EGL</h2>
125
Chia-I Wu411bba32010-06-11 12:47:14 +0800[diff] [blame]126<h3>Demos</h3>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]127
Chia-I Wu411bba32010-06-11 12:47:14 +0800[diff] [blame]128<p>There are demos for the client APIs supported by EGL. They can be found in
129mesa/demos repository.</p>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]130
131<h3>Environment Variables</h3>
132
133<p>There are several environment variables that control the behavior of EGL at
134runtime</p>
135
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]136<dl>
137<dt><code>EGL_DRIVERS_PATH</code></dt>
138<dd>
Chia-I Wu5d8646c2010-02-02 15:34:55 +0800[diff] [blame]139
140<p>By default, the main library will look for drivers in the directory where
141the drivers are installed to. This variable specifies a list of
142colon-separated directories where the main library will look for drivers, in
Chia-I Wu6fd8b6a2010-02-02 16:47:53 +0800[diff] [blame]143addition to the default directory. This variable is ignored for setuid/setgid
144binaries.</p>
Chia-I Wu5d8646c2010-02-02 15:34:55 +0800[diff] [blame]145
Chia-I Wucba77862011-01-04 00:53:19 +0800[diff] [blame]146<p>This variable is usually set to test an uninstalled build. For example, one
147may set</p>
148
149<pre>
150 $ export LD_LIBRARY_PATH=$mesa/lib
151 $ export EGL_DRIVERS_PATH=$mesa/lib/egl
152</pre>
153
154<p>to test a build without installation</p>
155
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]156</dd>
Chia-I Wu5d8646c2010-02-02 15:34:55 +0800[diff] [blame]157
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]158<dt><code>EGL_DRIVER</code></dt>
159<dd>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]160
Chia-I Wuc98ea262011-01-07 16:30:08 +0800[diff] [blame]161<p>This variable specifies a full path to or the name of an EGL driver. It
162forces the specified EGL driver to be loaded. It comes in handy when one wants
163to test a specific driver. This variable is ignored for setuid/setgid
164binaries.</p>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]165
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]166</dd>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]167
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]168<dt><code>EGL_PLATFORM</code></dt>
169<dd>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]170
Chia-I Wub365b152010-07-03 17:18:40 +0800[diff] [blame]171<p>This variable specifies the native platform. The valid values are the same
172as those for <code>--with-egl-platforms</code>. When the variable is not set,
173the main library uses the first platform listed in
Chia-I Wu3418f742010-11-02 23:55:56 +0800[diff] [blame]174<code>--with-egl-platforms</code> as the native platform.</p>
175
176<p>Extensions like <code>EGL_MESA_drm_display</code> define new functions to
177create displays for non-native platforms. These extensions are usually used by
178applications that support non-native platforms. Setting this variable is
179probably required only for some of the demos found in mesa/demo repository.</p>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]180
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]181</dd>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]182
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]183<dt><code>EGL_LOG_LEVEL</code></dt>
184<dd>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]185
186<p>This changes the log level of the main library and the drivers. The valid
187values are: <code>debug</code>, <code>info</code>, <code>warning</code>, and
188<code>fatal</code>.</p>
189
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]190</dd>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]191
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]192<dt><code>EGL_SOFTWARE</code></dt>
193<dd>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]194
195<p>For drivers that support both hardware and software rendering, setting this
196variable to true forces the use of software rendering.</p>
197
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]198</dd>
199</dl>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]200
201<h2>EGL Drivers</h2>
202
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]203<dl>
204<dt><code>egl_dri2</code></dt>
205<dd>
Chia-I Wu3418f742010-11-02 23:55:56 +0800[diff] [blame]206
207<p>This driver supports both <code>x11</code> and <code>drm</code> platforms.
Chia-I Wu65e8f812010-12-25 02:45:13 +0800[diff] [blame]208It functions as a DRI driver loader. For <code>x11</code> support, it talks to
209the X server directly using (XCB-)DRI2 protocol.</p>
210
211<p>This driver can share DRI drivers with <code>libGL</code>.</p>
Chia-I Wu3418f742010-11-02 23:55:56 +0800[diff] [blame]212
Andreas Boll76d4f9e2012-09-20 16:01:08 +0200[diff] [blame]213</dd>
Chia-I Wu3418f742010-11-02 23:55:56 +0800[diff] [blame]214
Chia-I Wu65e8f812010-12-25 02:45:13 +0800[diff] [blame]215<h2>Packaging</h2>
216
217<p>The ABI between the main library and its drivers are not stable. Nor is
Jose Fonseca5564c362015-03-03 16:01:22 +0000[diff] [blame^]218there a plan to stabilize it at the moment.</p>
Chia-I Wu65e8f812010-12-25 02:45:13 +0800[diff] [blame]219
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]220<h2>Developers</h2>
221
Jose Fonseca5564c362015-03-03 16:01:22 +0000[diff] [blame^]222<p>The sources of the main library and drivers can be found at
223<code>src/egl/</code>.</p>
Chia-I Wu14cbf322010-01-27 23:18:22 +0800[diff] [blame]224
Chia-I Wu14cbf322010-01-27 23:18:22 +0800[diff] [blame]225<h3>Lifetime of Display Resources</h3>
226
227<p>Contexts and surfaces are examples of display resources. They might live
228longer than the display that creates them.</p>
229
230<p>In EGL, when a display is terminated through <code>eglTerminate</code>, all
231display resources should be destroyed. Similarly, when a thread is released
Nathan Kidd0691b372014-01-03 16:44:00 -0700[diff] [blame]232through <code>eglReleaseThread</code>, all current display resources should be
233released. Another way to destroy or release resources is through functions
Chia-I Wu14cbf322010-01-27 23:18:22 +0800[diff] [blame]234such as <code>eglDestroySurface</code> or <code>eglMakeCurrent</code>.</p>
235
236<p>When a resource that is current to some thread is destroyed, the resource
237should not be destroyed immediately. EGL requires the resource to live until
238it is no longer current. A driver usually calls
239<code>eglIs&lt;Resource&gt;Bound</code> to check if a resource is bound
240(current) to any thread in the destroy callbacks. If it is still bound, the
241resource is not destroyed.</p>
242
243<p>The main library will mark destroyed current resources as unlinked. In a
244driver's <code>MakeCurrent</code> callback,
245<code>eglIs&lt;Resource&gt;Linked</code> can then be called to check if a newly
246released resource is linked to a display. If it is not, the last reference to
247the resource is removed and the driver should destroy the resource. But it
248should be careful here because <code>MakeCurrent</code> might be called with an
249uninitialized display.</p>
250
251<p>This is the only mechanism provided by the main library to help manage the
252resources. The drivers are responsible to the correct behavior as defined by
253EGL.</p>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]254
Chia-I Wu1b2b08c2010-02-05 12:44:45 +0800[diff] [blame]255<h3><code>EGL_RENDER_BUFFER</code></h3>
256
257<p>In EGL, the color buffer a context should try to render to is decided by the
258binding surface. It should try to render to the front buffer if the binding
259surface has <code>EGL_RENDER_BUFFER</code> set to
260<code>EGL_SINGLE_BUFFER</code>; If the same context is later bound to a
261surface with <code>EGL_RENDER_BUFFER</code> set to
262<code>EGL_BACK_BUFFER</code>, the context should try to render to the back
263buffer. However, the context is allowed to make the final decision as to which
264color buffer it wants to or is able to render to.</p>
265
266<p>For pbuffer surfaces, the render buffer is always
267<code>EGL_BACK_BUFFER</code>. And for pixmap surfaces, the render buffer is
268always <code>EGL_SINGLE_BUFFER</code>. Unlike window surfaces, EGL spec
269requires their <code>EGL_RENDER_BUFFER</code> values to be honored. As a
270result, a driver should never set <code>EGL_PIXMAP_BIT</code> or
271<code>EGL_PBUFFER_BIT</code> bits of a config if the contexts created with the
272config won't be able to honor the <code>EGL_RENDER_BUFFER</code> of pixmap or
273pbuffer surfaces.</p>
274
275<p>It should also be noted that pixmap and pbuffer surfaces are assumed to be
276single-buffered, in that <code>eglSwapBuffers</code> has no effect on them. It
277is desirable that a driver allocates a private color buffer for each pbuffer
278surface created. If the window system the driver supports has native pbuffers,
279or if the native pixmaps have more than one color buffers, the driver should
280carefully attach the native color buffers to the EGL surfaces, re-route them if
281required.</p>
282
283<p>There is no defined behavior as to, for example, how
284<code>glDrawBuffer</code> interacts with <code>EGL_RENDER_BUFFER</code>. Right
285now, it is desired that the draw buffer in a client API be fixed for pixmap and
286pbuffer surfaces. Therefore, the driver is responsible to guarantee that the
287client API renders to the specified render buffer for pixmap and pbuffer
288surfaces.</p>
289
Chia-I Wue16f5772010-02-17 19:52:29 +0800[diff] [blame]290<h3><code>EGLDisplay</code> Mutex</h3>
291
292The <code>EGLDisplay</code> will be locked before calling any of the dispatch
293functions (well, except for GetProcAddress which does not take an
294<code>EGLDisplay</code>). This guarantees that the same dispatch function will
295not be called with the sample display at the same time. If a driver has access
296to an <code>EGLDisplay</code> without going through the EGL APIs, the driver
297should as well lock the display before using it.
298
Andreas Bollb5da52a2012-09-18 18:57:02 +0200[diff] [blame]299</div>
Chia-I Wuada46052010-01-21 15:29:14 +0800[diff] [blame]300</body>
301</html>