<p>
-Mesa 1.2.4 introduced off-screen rendering, a facility for generating
-3-D imagery without having to open a window on your display. Mesa's
-simple off-screen rendering interface is completely operating system
-and window system independent so programs which use off-screen
-rendering should be very portable. This feature effectively
-enables you to use Mesa as an off-line, batch-oriented renderer.
+Mesa's off-screen rendering interface is used for rendering into
+user-allocated blocks of memory.
+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 "OSMesa" API provides 3 functions for making off-screen
+The <B>OSMesa</B> 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. See the demos/osdemo.c file for an example program.
-There is no facility for writing images to files. That's up to you.
+more information about the API functions.
</p>
+
<p>
-If you want to generate large images (larger than 1280x1024) you'll
-have to edit the src/config.h file to change MAX_WIDTH and MAX_HEIGHT
-then recompile Mesa. Image size should only be limited by available
-memory.
+There are several examples of OSMesa in the <code>progs/osdemos/</code>
+directory.
</p>
<H2>Deep color channels</H2>
<p>
- For some applications 8-bit color channels don't have sufficient
- accuracy (film and IBR, for example). If you're in this situation
- you'll be happy to know that Mesa 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.
+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.
</p>
+
<p>
- To build Mesa/OSMesa with 16-bit color channels:
+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>
+
+<p>
+To build Mesa/OSMesa for 16 and 8-bit color channel support:
<pre>
make realclean
make linux-osmesa16
</pre>
- For 32-bit channels:
+<p>
+To build Mesa/OSMesa for 32, 16 and 8-bit color channel support:
<pre>
make realclean
make linux-osmesa32
<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.
+</p>
+
+<p>
+If performance is important, compile Mesa for the channel size you're
+most interested in.
</p>
<p>
inclined.
</p>
-<p>
-BE WARNED: 16 and 32-bit channel support has not been exhaustively
-tested and there may be some bugs. However, a number of people have
-been using this feature successfully so it can't be too broken.
-</p>
-
-
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