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5 <title>Off-screen Rendering</title>
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10 <h1>Off-screen Rendering</h1>
14 Mesa's off-screen rendering interface is used for rendering into
15 user-allocated blocks of memory.
16 That is, the GL_FRONT colorbuffer is actually a buffer in main memory,
17 rather than a window on your display.
18 There are no window system or operating system dependencies.
19 One potential application is to use Mesa as an off-line, batch-style renderer.
23 The <b>OSMesa</b> API provides three basic functions for making off-screen
24 renderings: OSMesaCreateContext(), OSMesaMakeCurrent(), and
25 OSMesaDestroyContext(). See the Mesa/include/GL/osmesa.h header for
26 more information about the API functions.
30 There are several examples of OSMesa in the <code>progs/osdemos/</code>
35 <h2>Deep color channels</h2>
38 For some applications 8-bit color channels don't have sufficient
40 OSMesa supports 16-bit and 32-bit color channels through the OSMesa interface.
41 When using 16-bit channels, channels are GLushorts and RGBA pixels occupy
43 When using 32-bit channels, channels are GLfloats and RGBA pixels occupy
48 Before version 6.5.1, Mesa had to be recompiled to support exactly
49 one of 8, 16 or 32-bit channels.
50 With Mesa 6.5.1, Mesa can be compiled for either 8, 16 or 32-bit channels
51 and render into any of the smaller size channels.
52 For example, if Mesa's compiled for 32-bit channels, you can also render
53 16 and 8-bit channel images.
57 To build Mesa/OSMesa for 16 and 8-bit color channel support:
64 To build Mesa/OSMesa for 32, 16 and 8-bit color channel support:
71 You'll wind up with a library named libOSMesa16.so or libOSMesa32.so.
72 Otherwise, most Mesa configurations build an 8-bit/channel libOSMesa.so library
77 If performance is important, compile Mesa for the channel size you're
82 If you need to compile on a non-Linux platform, copy Mesa/configs/linux-osmesa16
83 to a new config file and edit it as needed. Then, add the new config name to
84 the top-level Makefile. Send a patch to the Mesa developers too, if you're