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| <TITLE>Off-screen Rendering</TITLE> |
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| <H1>Off-screen Rendering</H1> |
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| <p> |
| Mesa 1.2.4 introduced off-screen rendering, a facility for generating |
| 3-D imagery without having to open a window on your display. Mesa's |
| simple off-screen rendering interface is completely operating system |
| and window system independent so programs which use off-screen |
| rendering should be very portable. This feature effectively |
| enables you to use Mesa as an off-line, batch-oriented renderer. |
| </p> |
| <p> |
| The "OSMesa" API provides 3 functions for making off-screen |
| renderings: OSMesaCreateContext(), OSMesaMakeCurrent(), and |
| OSMesaDestroyContext(). See the Mesa/include/GL/osmesa.h header for |
| more information. See the demos/osdemo.c file for an example program. |
| There is no facility for writing images to files. That's up to you. |
| </p> |
| <p> |
| If you want to generate large images (larger than 1280x1024) you'll |
| have to edit the src/config.h file to change MAX_WIDTH and MAX_HEIGHT |
| then recompile Mesa. Image size should only be limited by available |
| memory. |
| </p> |
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| <H2>Deep color channels</H2> |
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| <p> |
| For some applications 8-bit color channels don't have sufficient |
| accuracy (film and IBR, for example). If you're in this situation |
| you'll be happy to know that Mesa supports 16-bit and 32-bit color |
| channels through the OSMesa interface. When using 16-bit channels, |
| channels are GLushorts and RGBA pixels occupy 8 bytes. When using 32-bit |
| channels, channels are GLfloats and RGBA pixels occupy 16 bytes. |
| </p> |
| <p> |
| To build Mesa/OSMesa with 16-bit color channels: |
| <pre> |
| cd Mesa-5.x/src |
| make -f Makefile.X11 clean |
| make -f Makefile.OSMesa16 linux-osmesa16 |
| </pre> |
| |
| For 32-bit channels: |
| <pre> |
| cd Mesa-5.x/src |
| make -f Makefile.X11 clean |
| make -f Makefile.OSMesa16 linux-osmesa32 |
| </pre> |
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| <p> |
| You'll wind up with a library named libOSMesa16.so or libOSMesa32.so. |
| </p> |
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| <p> |
| If you're not using Linux, you can easily edit Make-config and add |
| an appropriate configuration. |
| </p> |
| <p> |
| The Mesa/tests/osdemo16.c file (available via CVS) demonstrates how |
| to use this feature. |
| </p> |
| <p> |
| BE WARNED: 16 and 32-bit channel support has not been exhaustively |
| tested and there may be some bugs. However, a number of people have |
| been using this feature successfully so it can't be too broken. |
| </p> |
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