diff options
Diffstat (limited to 'docs/egl.html')
| -rw-r--r-- | docs/egl.html | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/docs/egl.html b/docs/egl.html new file mode 100644 index 00000000000..ccc233fca98 --- /dev/null +++ b/docs/egl.html @@ -0,0 +1,224 @@ +<html> + +<title>Mesa EGL</title> + +<head><link rel="stylesheet" type="text/css" href="mesa.css"></head> + +<body> + +<h1>Mesa EGL</h1> + +<p>The current version of EGL in Mesa implements EGL 1.4. More information +about EGL can be found at +<a href="http://www.khronos.org/egl/">http://www.khronos.org/egl/</a>.</p> + +<p>The Mesa's implementation of EGL uses a driver architecture. The main +library (<code>libEGL</code>) is window system neutral. It provides the EGL +API entry points and helper functions for use by the drivers. Drivers are +dynamically loaded by the main library and most of the EGL API calls are +directly dispatched to the drivers.</p> + +<p>The driver in use decides the window system to support. For drivers that +support hardware rendering, there are usually multiple drivers supporting the +same window system. Each one of of them supports a certain range of graphics +cards.</p> + +<h2>Build EGL</h2> + +<ol> +<li> +<p>Run <code>configure</code> with the desired state trackers and and enable +the Gallium driver for your hardware. For example</p> + +<pre> + $ ./configure --with-state-trackers=egl_g3d,es,vega --enable-gallium-intel +</pre> + +<p>The main library will be enabled by default. The <code>egl_g3d</code> state +tracker is needed by a number of EGL drivers. EGL drivers will be covered +later. The <a href="opengles.html">es state tracker</a> provides OpenGL ES 1.x +and 2.x and the <a href="openvg.html">vega state tracker</a> provides OpenVG +1.x.</p> +</li> + +<li>Build and install Mesa as usual.</li> +</ol> + +<p>In the given example, it will build and install <code>libEGL</code>, +<code>libGLESv1_CM</code>, <code>libGLESv2</code>, <code>libOpenVG</code>, and +one or more EGL drivers.</p> + +<h3>Configure Options</h3> + +<p>There are several options that control the build of EGL at configuration +time</p> + +<ul> +<li><code>--enable-egl</code> + +<p>By default, EGL is enabled. When disabled, the main library and the drivers +will not be built.</p> + +</li> + +<li><code>--with-egl-displays</code> + +<p>List the window system(s) to support. It is by default <code>x11</code>, +which supports the X Window System. Its argument is a comma separated string +like, for example, <code>--with-egl-displays=x11,kms</code>. Because an EGL +driver decides which window system to support, this example will enable two +(sets of) EGL drivers. One supports the X window system and the other supports +bare KMS (kernel modesetting).</p> + +</li> + +<li><code>--with-state-trackers</code> + +<p>The argument is a comma separated string. It is usually used to specify the +rendering APIs, like OpenGL ES or OpenVG, to build. But it should be noted +that a number of EGL drivers depend on the <code>egl_g3d</code> state tracker. +They will <em>not</em> be built without the <code>egl_g3d</code> state +tracker.</p> + +</li> +</ul> + +<h3>OpenGL</h3> + +<p>The OpenGL state tracker is not built in the above example. It should be +noted that the classic <code>libGL</code> is not a state tracker and cannot be +used with EGL (unless the EGL driver in use is <code>egl_glx</code>). To build +the OpenGL state tracker, one may append <code>glx</code> to +<code>--with-state-trackers</code> and manually build +<code>src/gallium/winsys/xlib/</code>.</p> + +<h2>Use EGL</h2> + +<p> The demos for OpenGL ES and OpenVG can be found in <code>progs/es1/</code>, +<code>progs/es2/</code> and <code>progs/openvg/</code>. You can use them to +test your build. For example,</p> + +<pre> + $ cd progs/es1/xegl + $ make + $ ./torus +</pre> + +<h3>Environment Variables</h3> + +<p>There are several environment variables that control the behavior of EGL at +runtime</p> + +<ul> +<li><code>EGL_DRIVER</code> + +<p>This variable forces the specified EGL driver to be loaded. It comes in +handy when one wants to test a specific driver.</p> + +</li> + +<li><code>EGL_DISPLAY</code> + +<p>When <code>EGL_DRIVER</code> is not set, the main library loads <em>all</em> +EGL drivers that support a certain window system. <code>EGL_DISPLAY</code> can +be used to specify the window system and the valid values are, for example, +<code>x11</code> or <code>kms</code>. When the variable is not set, the main +library defaults the value to the first window system listed in +<code>--with-egl-displays</code> at configuration time. + +</li> + +<li><code>EGL_LOG_LEVEL</code> + +<p>This changes the log level of the main library and the drivers. The valid +values are: <code>debug</code>, <code>info</code>, <code>warning</code>, and +<code>fatal</code>.</p> + +</li> + +<li><code>EGL_SOFTWARE</code> + +<p>For drivers that support both hardware and software rendering, setting this +variable to true forces the use of software rendering.</p> + +</li> +</ul> + +<h2>EGL Drivers</h2> + +<p>There are two categories of EGL drivers: Gallium and classic.</p> + +<p>Gallium EGL drivers supports all rendering APIs specified in EGL 1.4. The +support for optional EGL functions and EGL extensions is usually more complete +than the classic ones. These drivers depend on the <code>egl_g3d</code> state +tracker to build. The available drivers are</p> + +<ul> +<li><code>egl_<dpy>_i915</code></li> +<li><code>egl_<dpy>_i965</code></li> +<li><code>egl_<dpy>_radeon</code></li> +<li><code>egl_<dpy>_nouveau</code></li> +<li><code>egl_<dpy>_vmwgfx</code></li> +</ul> + +<p><code><dpy></code> is given by <code>--with-egl-displays</code> at +configuration time. There will be one EGL driver for each combination of the +displays listed and the hardware drivers enabled.</p> + +<p>Classic EGL drivers, on the other hand, supports only OpenGL as its +rendering API. They can be found under <code>src/egl/drivers/</code>. There +are 3 of them</p> + +<ul> +<li><code>egl_glx</code> + +<p>This driver provides a wrapper to GLX. It uses exclusively GLX to implement +the EGL API. It supports both direct and indirect rendering when the GLX does. +It is accelerated when the GLX is. As such, it cannot provide functions that +is not available in GLX or GLX extensions.</p> +</li> + +<li><code>egl_xdri</code> + +<p>This driver supports the X Window System as its window system. It functions +as a DRI driver loader. Unlike <code>egl_glx</code>, it has no dependency on +<code>libGL</code>. It talks to the X server directly using DRI or DRI2 +protocols. It also talks minimal GLX protocol for things like available +visuals or fbconfigs. With direct access to the DRI drivers, it has the +potential to support more EGL functions that are not possible with +<code>egl_glx</code></p> + +</li> +<li><code>egl_dri</code> + +<p>This driver lacks maintenance and does <em>not</em> build. It is similiar +to <code>egl_xdri</code> in that it functions as a DRI driver loader. But +unlike <code>egl_xdri</code>, it supports Linux framebuffer devices as its +window system and supports EGL_MESA_screen_surface extension. It loads only +DRI1 drivers. As DRI1 drivers is phasing out, it might be better to rewrite +the driver to support KMS and DRI2.</p> + +</li> +</ul> + +<p>To use the classic drivers, one must manually set <code>EGL_DRIVER</code> at +runtime.</p> + +<h2>Developers</h2> + +The sources of the main library and the classic drivers can be found at +<code>src/egl/</code>. The sources of the <code>egl_g3d</code> state tracker +can be found at <code>src/gallium/state_trackers/egl_g3d/</code>. + +<h3>TODOs</h3> + +<ul> +<li>Thread safety</li> +<li>Pass the conformance tests</li> +<li>Better automatic driver selection: <code>EGL_DISPLAY</code> loads all +drivers and might eat too much memory.</li> + +</ul> + +</body> +</html> |