w, the DRI drivers are included in the Mesa tree and can be compiled
separately from the X server.
Just follow the Mesa <a href="install.html">compilation instructions</a>.
</p>


<h2>1.6 Are there other open-source implementations of OpenGL?</h2>
<p>
Yes, SGI's <a href="http://oss.sgi.com/projects/ogl-sample/index.html">
OpenGL Sample Implementation (SI)</a> is available.
The SI was written during the time that OpenGL was originally designed.
Unfortunately, development of the SI has stagnated.
Mesa is much