docs/osmesa.html

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   3 <TITLE>Off-screen Rendering</TITLE>
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   7 <H1>Off-screen Rendering</H1>
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   9
  10 <p>
  11 Mesa 1.2.4 introduced off-screen rendering, a facility for generating
  12 3-D imagery without having to open a window on your display.  Mesa's
  13 simple off-screen rendering interface is completely operating system
  14 and window system independent so programs which use off-screen
  15 rendering should be very portable.  This feature effectively
  16 enables you to use Mesa as an off-line, batch-oriented renderer.
  17 </p>
  18 <p>
  19 The "OSMesa" API provides 3 functions for making off-screen
  20 renderings: OSMesaCreateContext(), OSMesaMakeCurrent(), and
  21 OSMesaDestroyContext().  See the Mesa/include/GL/osmesa.h header for
  22 more information.  See the demos/osdemo.c file for an example program.
  23 There is no facility for writing images to files.  That's up to you.
  24 </p>
  25 <p>
  26 If you want to generate large images (larger than 1280x1024) you'll
  27 have to edit the src/config.h file to change MAX_WIDTH and MAX_HEIGHT
  28 then recompile Mesa.  Image size should only be limited by available
  29 memory.
  30 </p>
  31
  32
  33 <H2>Deep color channels</H2>
  34
  35 <p>
  36    For some applications 8-bit color channels don't have sufficient
  37    accuracy (film and IBR, for example).  If you're in this situation
  38    you'll be happy to know that Mesa supports 16-bit and 32-bit color
  39    channels through the OSMesa interface.  When using 16-bit channels,
  40    channels are GLushorts and pixels occupy 8 bytes.  When using 32-bit
  41    channels, channels are GLfloats and pixels occupy 16 bytes.
  42 </p>
  43 <p>
  44    To build Mesa/OSMesa with 16-bit color channels:
  45 <pre>
  46       cd Mesa-4.x/src
  47       make -f Makefile.X11 clean
  48       make -f Makefile.OSMesa16 linux-osmesa16
  49 </pre>
  50
  51    For 32-bit channels:
  52 <pre>
  53       cd Mesa-4.x/src
  54       make -f Makefile.X11 clean
  55       make -f Makefile.OSMesa16 linux-osmesa32
  56 </pre>
  57
  58 <p>
  59 If you're not using Linux, you can easily edit Make-config and add
  60 an appropriate configuration.
  61 </p>
  62 <p>
  63 The Mesa/tests/osdemo16.c file (available via CVS) demonstrates how
  64 to use this feature.
  65 </p>
  66 <p>
  67 BE WARNED: 16 and 32-bit channel support has not been exhaustively
  68 tested and there may be some bugs.  However, a number of people have
  69 been using this feature successfully so it can't be too broken.
  70 </p>
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