From 6f86b934e618c6b55d3d9414720d1935c654ae7b Mon Sep 17 00:00:00 2001 From: Brian Paul Date: Mon, 11 Mar 2013 18:31:22 -0600 Subject: [PATCH] docs: rewrite the OSMesa info / instructions MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Reviewed-by: José Fonseca --- docs/osmesa.html | 65 ++++++++++++++++++++++---------------------------------- 1 file changed, 25 insertions(+), 40 deletions(-) diff --git a/docs/osmesa.html b/docs/osmesa.html index b0609cf..8487545 100644 --- a/docs/osmesa.html +++ b/docs/osmesa.html @@ -18,77 +18,62 @@

-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.

-The OSMesa 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.

-There are several examples of OSMesa in the mesa/demos repository. +The OSMesa interface may be used with any of three software renderers:

+
    +
  1. llvmpipe - this is the high-performance Gallium LLVM driver +
  2. softpipe - this it the reference Gallium software driver +
  3. swrast - this is the legacy Mesa software rasterizer +
-

Deep color channels

-

-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.

-

-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. -

+

Building OSMesa

-To build Mesa/OSMesa for 16 and 8-bit color channel support: +Configure and build Mesa with something like: + 

-      make realclean
-      make linux-osmesa16
+configure --enable-osmesa --disable-driglx-direct --disable-dri --with-gallium-drivers=swrast
+make

-To build Mesa/OSMesa for 32, 16 and 8-bit color channel support: -

-      make realclean
-      make linux-osmesa32
-
+Make sure you have LLVM installed first if you want to use the llvmpipe driver. +

-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:

+
+lib/libOSMesa.so  (swrast-based OSMesa)
+lib/gallium/libOSMsea.so  (gallium-based OSMesa)
+

-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.

-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

-- 2.7.4