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3<title>OpenGL ES</title>
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5<head><link rel="stylesheet" type="text/css" href="mesa.css"></head>
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7<body>
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9<h1>OpenGL ES</h1>
10
11<p>Mesa implements OpenGL ES 1.1 and OpenGL ES 2.0.  More informations about
12OpenGL ES can be found at <a href="http://www.khronos.org/opengles/"
13target="_parent"> http://www.khronos.org/opengles/</a>.</p>
14
15<p>OpenGL ES depends on a working EGL implementation.  Please refer to
16<a href="egl.html">Mesa EGL</a> for more information about EGL.</p>
17
18<h2>Build the Libraries</h2>
19<ol>
20<li>Run <code>configure</code> with <code>--enable-gles-overlay</code> and enable the Gallium driver for your hardware.</li>
21<li>Build and install Mesa as usual.</li>
22</ol>
23
24Alternatively, if XCB-DRI2 is installed on the system, one can use
25<code>egl_dri2</code> EGL driver with OpenGL|ES-enabled DRI drivers
26
27<ol>
28<li>Run <code>configure</code> with <code>--enable-gles1 --enable-gles2</code>.</li>
29<li>Build and install Mesa as usual.</li>
30</ol>
31
32<p>Both methods will install libGLESv1_CM, libGLESv2, libEGL, and one or more
33EGL drivers for your hardware.</p>
34
35<h2>Run the Demos</h2>
36
37<p>There are some demos in <code>progs/egl/</code>.  You can use them to test
38your build.  For example,</p>
39
40<pre>
41  $ cd progs/egl/eglut
42  $ make
43  $ cd /opengles1
44  $ make
45  $ /torus_x11
46</pre>
47
48<h2>Developers</h2>
49
50<h3>Internal Libraries</h3>
51
52<table border="1" style="text-align: center;">
53	<tr><td>Library Name</td><td>Used By</td><td>Enabled</td><td>OpenGL</td><td>OpenGL ES 1.x</td><td>OpenGL ES 2.x</td></tr>
54	<tr><td><code>src/mesa/libmesa.a</td><td>Classic DRI drivers</td><td>y</td><td>y</td><td>--enable-gles1</td><td>--enable-gles2</td></tr>
55	<tr><td><code>src/mesa/libmesagallium.a</td><td>Gallium EGL and DRI drivers</td><td>y</td><td>y</td><td>--enable-gles1</td><td>--enable-gles2</td></tr>
56	<tr><td><code>src/mesa/es/libes1gallium.a</td><td>Gallium EGL drivers</td><td>--enable-gles-overlay</td><td>n</td><td>y</td><td>n</td></tr>
57	<tr><td><code>src/mesa/es/libes2gallium.a</td><td>Gallium EGL drivers</td><td>--enable-gles-overlay</td><td>n</td><td>n</td><td>y</td></tr>
58</table>
59
60<h3>Dispatch Table</h3>
61
62<p>OpenGL ES has an additional indirection when dispatching fucntions</p>
63
64<pre>
65  Mesa:       glFoo() --&gt; _mesa_Foo()
66  OpenGL ES:  glFoo() --&gt; _es_Foo() --&gt; _mesa_Foo()
67</pre>
68
69<p>The indirection serves several purposes</p>
70
71<ul>
72<li>When a function is in Mesa and the type matches, it checks the arguments and calls the Mesa function.</li>
73<li>When a function is in Mesa but the type mismatches, it checks and converts the arguments before calling the Mesa function.</li>
74<li>When a function is not available in Mesa, or accepts arguments that are not available in OpenGL, it provides its own implementation.</li>
75</ul>
76
77<p>Other than the last case, OpenGL ES uses <code>APIspec.xml</code> to generate functions to check and/or converts the arguments.</p>
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