docs: rewrite the OSMesa info / instructions

Reviewed-by: José Fonseca <jfonseca@vmware.com>

diff --git a/docs/osmesa.html b/docs/osmesa.html
index b0609cf88c7072bae534f0789fd4de5885533589..848754570df2e8d225bbfc87df5442795383920a 100644 (file)
--- a/docs/osmesa.html
+++ b/docs/osmesa.html
@@ -18,77 +18,62 @@
 
 
 <p>
-Mesa's off-screen rendering interface is used for rendering into
-user-allocated blocks of memory.
+Mesa's off-screen interface is used for rendering into user-allocated memory
+without any sort of window system or operating system dependencies.
 That is, the GL_FRONT colorbuffer is actually a buffer in main memory,
 rather than a window on your display.
-There are no window system or operating system dependencies.
-One potential application is to use Mesa as an off-line, batch-style renderer.
 </p>
 
 <p>
-The <b>OSMesa</b> API provides three basic functions for making off-screen
+The OSMesa API provides three basic functions for making off-screen
 renderings: OSMesaCreateContext(), OSMesaMakeCurrent(), and
 OSMesaDestroyContext().  See the Mesa/include/GL/osmesa.h header for
 more information about the API functions.
 </p>
 
 <p>
-There are several examples of OSMesa in the mesa/demos repository.
+The OSMesa interface may be used with any of three software renderers:
 </p>
+<ol>
+<li>llvmpipe - this is the high-performance Gallium LLVM driver
+<li>softpipe - this it the reference Gallium software driver
+<li>swrast - this is the legacy Mesa software rasterizer
+</ol>
 
 
-<h2>Deep color channels</h2>
-
 <p>
-For some applications 8-bit color channels don't have sufficient
-precision.
-OSMesa supports 16-bit and 32-bit color channels through the OSMesa interface.
-When using 16-bit channels, channels are GLushorts and RGBA pixels occupy
-8 bytes.
-When using 32-bit channels, channels are GLfloats and RGBA pixels occupy
-16 bytes.
+There are several examples of OSMesa in the mesa/demos repository.
 </p>
 
-<p>
-Before version 6.5.1, Mesa had to be recompiled to support exactly
-one of 8, 16 or 32-bit channels.
-With Mesa 6.5.1, Mesa can be compiled for either 8, 16 or 32-bit channels
-and render into any of the smaller size channels.
-For example, if Mesa's compiled for 32-bit channels, you can also render
-16 and 8-bit channel images.
-</p>
+<h1>Building OSMesa</h1>
 
 <p>
-To build Mesa/OSMesa for 16 and 8-bit color channel support:
+Configure and build Mesa with something like:
+
 <pre>
-      make realclean
-      make linux-osmesa16
+configure --enable-osmesa --disable-driglx-direct --disable-dri --with-gallium-drivers=swrast
+make
 </pre>
 
 <p>
-To build Mesa/OSMesa for 32, 16 and 8-bit color channel support:
-<pre>
-      make realclean
-      make linux-osmesa32
-</pre>
+Make sure you have LLVM installed first if you want to use the llvmpipe driver.
+</p>
 
 <p>
-You'll wind up with a library named libOSMesa16.so or libOSMesa32.so.
-Otherwise, most Mesa configurations build an 8-bit/channel libOSMesa.so library
-by default.
+When the build is complete you should find:
 </p>
+<pre>
+lib/libOSMesa.so  (swrast-based OSMesa)
+lib/gallium/libOSMsea.so  (gallium-based OSMesa)
+</pre>
 
 <p>
-If performance is important, compile Mesa for the channel size you're
-most interested in.
+Set your LD_LIBRARY_PATH to point to one directory or the other to select
+the library you want to use.
 </p>
 
 <p>
-If you need to compile on a non-Linux platform, copy Mesa/configs/linux-osmesa16
-to a new config file and edit it as needed.  Then, add the new config name to
-the top-level Makefile.  Send a patch to the Mesa developers too, if you're
-inclined.
+When you link your application, link with -lOSMesa
 </p>
 
 </div>