-<HTML>
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
+<html lang="en">
+<head>
+ <meta http-equiv="content-type" content="text/html; charset=utf-8">
+ <title>Off-screen Rendering</title>
+ <link rel="stylesheet" type="text/css" href="mesa.css">
+</head>
+<body>
-<TITLE>Off-screen Rendering</TITLE>
+<div class="header">
+ <h1>The Mesa 3D Graphics Library</h1>
+</div>
-<link rel="stylesheet" type="text/css" href="mesa.css"></head>
+<iframe src="contents.html"></iframe>
+<div class="content">
-<BODY>
-
-<H1>Off-screen Rendering</H1>
+<h1>Off-screen Rendering</h1>
<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 <code>progs/osdemo/</code>
-directory.
+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>
-</BODY>
-</HTML>
+</div>
+</body>
+</html>
projects / mesa.git / blobdiff