docs/opengles.html

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  10 <h1>OpenGL ES</h1>
  11
  12 <p>Mesa implements OpenGL ES 1.1 and OpenGL ES 2.0.  More informations about
  13 OpenGL ES can be found at <a href="http://www.khronos.org/opengles/"
  14 target="_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
  25 Alternatively, 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
  34 EGL 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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