75 lines
2.2 KiB
HTML
75 lines
2.2 KiB
HTML
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<HTML>
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<TITLE>Off-screen Rendering</TITLE>
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<BODY text="#000000" bgcolor="#55bbff" link="#111188">
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<H1>Off-screen Rendering</H1>
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<p>
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Mesa 1.2.4 introduced off-screen rendering, a facility for generating
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3-D imagery without having to open a window on your display. Mesa's
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simple off-screen rendering interface is completely operating system
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and window system independent so programs which use off-screen
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rendering should be very portable. This feature effectively
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enables you to use Mesa as an off-line, batch-oriented renderer.
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</p>
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<p>
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The "OSMesa" API provides 3 functions for making off-screen
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renderings: OSMesaCreateContext(), OSMesaMakeCurrent(), and
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OSMesaDestroyContext(). See the Mesa/include/GL/osmesa.h header for
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more information. See the demos/osdemo.c file for an example program.
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There is no facility for writing images to files. That's up to you.
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</p>
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<p>
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If you want to generate large images (larger than 1280x1024) you'll
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have to edit the src/config.h file to change MAX_WIDTH and MAX_HEIGHT
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then recompile Mesa. Image size should only be limited by available
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memory.
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</p>
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<H2>Deep color channels</H2>
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<p>
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For some applications 8-bit color channels don't have sufficient
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accuracy (film and IBR, for example). If you're in this situation
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you'll be happy to know that Mesa supports 16-bit and 32-bit color
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channels through the OSMesa interface. When using 16-bit channels,
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channels are GLushorts and pixels occupy 8 bytes. When using 32-bit
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channels, channels are GLfloats and pixels occupy 16 bytes.
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</p>
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<p>
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To build Mesa/OSMesa with 16-bit color channels:
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<pre>
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cd Mesa-4.x/src
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make -f Makefile.X11 clean
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make -f Makefile.OSMesa16 linux-osmesa16
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</pre>
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For 32-bit channels:
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<pre>
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cd Mesa-4.x/src
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make -f Makefile.X11 clean
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make -f Makefile.OSMesa16 linux-osmesa32
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</pre>
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<p>
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If you're not using Linux, you can easily edit Make-config and add
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an appropriate configuration.
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</p>
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<p>
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The Mesa/tests/osdemo16.c file (available via CVS) demonstrates how
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to use this feature.
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</p>
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<p>
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BE WARNED: 16 and 32-bit channel support has not been exhaustively
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tested and there may be some bugs. However, a number of people have
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been using this feature successfully so it can't be too broken.
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</p>
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</BODY>
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</HTML>
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