docs/opengles.html

   1 <html>
   2
   3 <title>OpenGL ES</title>
   4
   5 <head><link rel="stylesheet" type="text/css" href="mesa.css"></head>
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   7 <body>
   8
   9 <h1>OpenGL ES</h1>
  10
  11 <p>Mesa implements OpenGL ES 1.1 and OpenGL ES 2.0.  More informations about
  12 OpenGL ES can be found at <a href="http://www.khronos.org/opengles/"
  13 target="_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
  24 Alternatively, 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
  33 EGL 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
  38 your 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>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>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>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>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>
  78
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  80 </html>