docs/opengles.html

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  11   <h1>The Mesa 3D Graphics Library</h1>
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  16
  17 <h1>OpenGL ES</h1>
  18
  19 <p>Mesa implements OpenGL ES 1.1 and OpenGL ES 2.0.  More information about
  20 OpenGL ES can be found at <a href="https://www.khronos.org/opengles/">
  21 https://www.khronos.org/opengles/</a>.</p>
  22
  23 <p>OpenGL ES depends on a working EGL implementation.  Please refer to
  24 <a href="egl.html">Mesa EGL</a> for more information about EGL.</p>
  25
  26 <h2>Build the Libraries</h2>
  27 <ol>
  28 <li>Run <code>configure</code> with <code>--enable-gles1 --enable-gles2</code> and enable the Gallium driver for your hardware.</li>
  29 <li>Build and install Mesa as usual.</li>
  30 </ol>
  31
  32 Alternatively, if XCB-DRI2 is installed on the system, one can use
  33 <code>egl_dri2</code> EGL driver with OpenGL|ES-enabled DRI drivers
  34
  35 <ol>
  36 <li>Run <code>configure</code> with <code>--enable-gles1 --enable-gles2</code>.</li>
  37 <li>Build and install Mesa as usual.</li>
  38 </ol>
  39
  40 <p>Both methods will install libGLESv1_CM, libGLESv2, libEGL, and one or more
  41 EGL drivers for your hardware.</p>
  42
  43 <h2>Run the Demos</h2>
  44
  45 <p>There are some demos in <code>mesa/demos</code> repository.</p>
  46
  47 <h2>Developers</h2>
  48
  49 <h3>Dispatch Table</h3>
  50
  51 <p>OpenGL ES has an additional indirection when dispatching functions</p>
  52
  53 <pre>
  54   Mesa:       glFoo() --&gt; _mesa_Foo()
  55   OpenGL ES:  glFoo() --&gt; _es_Foo() --&gt; _mesa_Foo()
  56 </pre>
  57
  58 <p>The indirection serves several purposes</p>
  59
  60 <ul>
  61 <li>When a function is in Mesa and the type matches, it checks the arguments and calls the Mesa function.</li>
  62 <li>When a function is in Mesa but the type mismatches, it checks and converts the arguments before calling the Mesa function.</li>
  63 <li>When a function is not available in Mesa, or accepts arguments that are not available in OpenGL, it provides its own implementation.</li>
  64 </ul>
  65
  66 <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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