docs/osmesa.html - chromium/deps/mesa - Git at Google

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 <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>

 <h1>Off-screen Rendering</h1>


 <p>
 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 <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 about the API functions.
 </p>

 <p>
 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
 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>
 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>

 <p>
 To build Mesa/OSMesa for 32, 16 and 8-bit color channel support:
 <pre>
       make realclean
       make linux-osmesa32
 </pre>

 <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>
 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.
 </p>

 </body>
 </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>

	<h1>Off-screen Rendering</h1>


	<p>
	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 <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 about the API functions.
	</p>

	<p>
	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
	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>
	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>

	<p>
	To build Mesa/OSMesa for 32, 16 and 8-bit color channel support:
	<pre>
	make realclean
	make linux-osmesa32
	</pre>

	<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>
	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.
	</p>

	</body>
	</html>