78 lines
2.3 KiB
HTML
78 lines
2.3 KiB
HTML
<HTML>
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<TITLE>Off-screen Rendering</TITLE>
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<link rel="stylesheet" type="text/css" href="mesa.css"></head>
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<BODY>
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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 RGBA pixels occupy 8 bytes. When using 32-bit
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channels, channels are GLfloats and RGBA 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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make realclean
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make linux-osmesa16
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</pre>
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For 32-bit channels:
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<pre>
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make realclean
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make linux-osmesa32
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</pre>
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<p>
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You'll wind up with a library named libOSMesa16.so or libOSMesa32.so.
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</p>
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<p>
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If you need to compile on a non-Linux platform, copy Mesa/configs/linux-osmesa16
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to a new config file and edit it as needed. Then, add the new config name to
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the top-level Makefile. Send a patch to the Mesa developers too, if you're
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inclined.
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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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