docs/osmesa.html

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   3 <TITLE>Off-screen Rendering</TITLE>
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   9 <H1>Off-screen Rendering</H1>
  10
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  12 <p>
  13 Mesa 1.2.4 introduced off-screen rendering, a facility for generating
  14 3-D imagery without having to open a window on your display.  Mesa's
  15 simple off-screen rendering interface is completely operating system
  16 and window system independent so programs which use off-screen
  17 rendering should be very portable.  This feature effectively
  18 enables you to use Mesa as an off-line, batch-oriented renderer.
  19 </p>
  20 <p>
  21 The "OSMesa" API provides 3 functions for making off-screen
  22 renderings: OSMesaCreateContext(), OSMesaMakeCurrent(), and
  23 OSMesaDestroyContext().  See the Mesa/include/GL/osmesa.h header for
  24 more information.  See the demos/osdemo.c file for an example program.
  25 There is no facility for writing images to files.  That's up to you.
  26 </p>
  27 <p>
  28 If you want to generate large images (larger than 1280x1024) you'll
  29 have to edit the src/config.h file to change MAX_WIDTH and MAX_HEIGHT
  30 then recompile Mesa.  Image size should only be limited by available
  31 memory.
  32 </p>
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  35 <H2>Deep color channels</H2>
  36
  37 <p>
  38    For some applications 8-bit color channels don't have sufficient
  39    accuracy (film and IBR, for example).  If you're in this situation
  40    you'll be happy to know that Mesa supports 16-bit and 32-bit color
  41    channels through the OSMesa interface.  When using 16-bit channels,
  42    channels are GLushorts and RGBA pixels occupy 8 bytes.  When using 32-bit
  43    channels, channels are GLfloats and RGBA pixels occupy 16 bytes.
  44 </p>
  45 <p>
  46    To build Mesa/OSMesa with 16-bit color channels:
  47 <pre>
  48       make realclean
  49       make linux-osmesa16
  50 </pre>
  51
  52    For 32-bit channels:
  53 <pre>
  54       make realclean
  55       make linux-osmesa32
  56 </pre>
  57
  58 <p>
  59 You'll wind up with a library named libOSMesa16.so or libOSMesa32.so.
  60 </p>
  61
  62 <p>
  63 If you need to compile on a non-Linux platform, copy Mesa/configs/linux-osmesa16
  64 to a new config file and edit it as needed.  Then, add the new config name to
  65 the top-level Makefile.  Send a patch to the Mesa developers too, if you're
  66 inclined.
  67 </p>
  68
  69 <p>
  70 BE WARNED: 16 and 32-bit channel support has not been exhaustively
  71 tested and there may be some bugs.  However, a number of people have
  72 been using this feature successfully so it can't be too broken.
  73 </p>
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