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5  <title>OpenGL ES</title>
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9
10<h1>OpenGL ES</h1>
11
12<p>Mesa implements OpenGL ES 1.1 and OpenGL ES 2.0.  More informations about
13OpenGL ES can be found at <a href="http://www.khronos.org/opengles/"
14target="_parent"> http://www.khronos.org/opengles/</a>.</p>
15
16<p>OpenGL ES depends on a working EGL implementation.  Please refer to
17<a href="egl.html">Mesa EGL</a> for more information about EGL.</p>
18
19<h2>Build the Libraries</h2>
20<ol>
21<li>Run <code>configure</code> with <code>--enable-gles1 --enable-gles2</code> and enable the Gallium driver for your hardware.</li>
22<li>Build and install Mesa as usual.</li>
23</ol>
24
25Alternatively, if XCB-DRI2 is installed on the system, one can use
26<code>egl_dri2</code> EGL driver with OpenGL|ES-enabled DRI drivers
27
28<ol>
29<li>Run <code>configure</code> with <code>--enable-gles1 --enable-gles2</code>.</li>
30<li>Build and install Mesa as usual.</li>
31</ol>
32
33<p>Both methods will install libGLESv1_CM, libGLESv2, libEGL, and one or more
34EGL drivers for your hardware.</p>
35
36<h2>Run the Demos</h2>
37
38<p>There are some demos in <code>mesa/demos</code> repository.</p>
39
40<h2>Developers</h2>
41
42<h3>Dispatch Table</h3>
43
44<p>OpenGL ES has an additional indirection when dispatching fucntions</p>
45
46<pre>
47  Mesa:       glFoo() --&gt; _mesa_Foo()
48  OpenGL ES:  glFoo() --&gt; _es_Foo() --&gt; _mesa_Foo()
49</pre>
50
51<p>The indirection serves several purposes</p>
52
53<ul>
54<li>When a function is in Mesa and the type matches, it checks the arguments and calls the Mesa function.</li>
55<li>When a function is in Mesa but the type mismatches, it checks and converts the arguments before calling the Mesa function.</li>
56<li>When a function is not available in Mesa, or accepts arguments that are not available in OpenGL, it provides its own implementation.</li>
57</ul>
58
59<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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