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Andreas Boll	ecd5c7c	2012-06-12 09:05:03 +0200	[diff] [blame]	1	<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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				3	<head>
				4	<meta http-equiv="content-type" content="text/html; charset=utf-8">
				5	<title>Off-screen Rendering</title>
				6	<link rel="stylesheet" type="text/css" href="mesa.css">
				7	</head>
				8	<body>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	9
Andreas Boll	b5da52a	2012-09-18 18:57:02 +0200	[diff] [blame]	10	<div class="header">
				11	<h1>The Mesa 3D Graphics Library</h1>
				12	</div>
				13
				14	<iframe src="contents.html"></iframe>
				15	<div class="content">
				16
Andreas Boll	ecd5c7c	2012-06-12 09:05:03 +0200	[diff] [blame]	17	<h1>Off-screen Rendering</h1>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	18
				19
				20	<p>
Brian Paul	e35b905	2006-05-19 03:42:16 +0000	[diff] [blame]	21	Mesa's off-screen rendering interface is used for rendering into
				22	user-allocated blocks of memory.
				23	That is, the GL_FRONT colorbuffer is actually a buffer in main memory,
				24	rather than a window on your display.
				25	There are no window system or operating system dependencies.
				26	One potential application is to use Mesa as an off-line, batch-style renderer.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	27	</p>
Brian Paul	e35b905	2006-05-19 03:42:16 +0000	[diff] [blame]	28
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	29	<p>
Andreas Boll	210a27d	2012-06-12 09:05:36 +0200	[diff] [blame]	30	The <b>OSMesa</b> API provides three basic functions for making off-screen
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	31	renderings: OSMesaCreateContext(), OSMesaMakeCurrent(), and
				32	OSMesaDestroyContext(). See the Mesa/include/GL/osmesa.h header for
Brian Paul	e35b905	2006-05-19 03:42:16 +0000	[diff] [blame]	33	more information about the API functions.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	34	</p>
Brian Paul	e35b905	2006-05-19 03:42:16 +0000	[diff] [blame]	35
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	36	<p>
Brian Paul	b0613d8	2010-02-09 11:21:41 -0700	[diff] [blame]	37	There are several examples of OSMesa in the <code>progs/osdemos/</code>
Brian Paul	e35b905	2006-05-19 03:42:16 +0000	[diff] [blame]	38	directory.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	39	</p>
				40
				41
Andreas Boll	210a27d	2012-06-12 09:05:36 +0200	[diff] [blame]	42	<h2>Deep color channels</h2>
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	43
				44	<p>
Brian Paul	e35b905	2006-05-19 03:42:16 +0000	[diff] [blame]	45	For some applications 8-bit color channels don't have sufficient
				46	precision.
				47	OSMesa supports 16-bit and 32-bit color channels through the OSMesa interface.
				48	When using 16-bit channels, channels are GLushorts and RGBA pixels occupy
				49	8 bytes.
				50	When using 32-bit channels, channels are GLfloats and RGBA pixels occupy
				51	16 bytes.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	52	</p>
Brian Paul	e35b905	2006-05-19 03:42:16 +0000	[diff] [blame]	53
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	54	<p>
Brian Paul	e35b905	2006-05-19 03:42:16 +0000	[diff] [blame]	55	Before version 6.5.1, Mesa had to be recompiled to support exactly
				56	one of 8, 16 or 32-bit channels.
				57	With Mesa 6.5.1, Mesa can be compiled for either 8, 16 or 32-bit channels
				58	and render into any of the smaller size channels.
				59	For example, if Mesa's compiled for 32-bit channels, you can also render
				60	16 and 8-bit channel images.
				61	</p>
				62
				63	<p>
				64	To build Mesa/OSMesa for 16 and 8-bit color channel support:
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	65	<pre>
Brian Paul	58be9e6	2004-09-24 20:31:02 +0000	[diff] [blame]	66	make realclean
				67	make linux-osmesa16
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	68	</pre>
				69
Brian Paul	e35b905	2006-05-19 03:42:16 +0000	[diff] [blame]	70	<p>
				71	To build Mesa/OSMesa for 32, 16 and 8-bit color channel support:
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	72	<pre>
Brian Paul	58be9e6	2004-09-24 20:31:02 +0000	[diff] [blame]	73	make realclean
				74	make linux-osmesa32
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	75	</pre>
				76
				77	<p>
Brian Paul	7357f20	2003-05-02 15:05:02 +0000	[diff] [blame]	78	You'll wind up with a library named libOSMesa16.so or libOSMesa32.so.
Brian Paul	e35b905	2006-05-19 03:42:16 +0000	[diff] [blame]	79	Otherwise, most Mesa configurations build an 8-bit/channel libOSMesa.so library
				80	by default.
				81	</p>
				82
				83	<p>
				84	If performance is important, compile Mesa for the channel size you're
				85	most interested in.
Brian Paul	7357f20	2003-05-02 15:05:02 +0000	[diff] [blame]	86	</p>
				87
				88	<p>
Brian Paul	58be9e6	2004-09-24 20:31:02 +0000	[diff] [blame]	89	If you need to compile on a non-Linux platform, copy Mesa/configs/linux-osmesa16
				90	to a new config file and edit it as needed. Then, add the new config name to
				91	the top-level Makefile. Send a patch to the Mesa developers too, if you're
				92	inclined.
Brian Paul	0b27ace	2003-03-08 17:38:57 +0000	[diff] [blame]	93	</p>
Brian Paul	58be9e6	2004-09-24 20:31:02 +0000	[diff] [blame]	94
Andreas Boll	b5da52a	2012-09-18 18:57:02 +0200	[diff] [blame]	95	</div>
Andreas Boll	ecd5c7c	2012-06-12 09:05:03 +0200	[diff] [blame]	96	</body>
				97	</html>