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5  <title>Off-screen Rendering</title>
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10<div class="header">
11  <h1>The Mesa 3D Graphics Library</h1>
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16
17<h1>Off-screen Rendering</h1>
18
19
20<p>
21Mesa's off-screen interface is used for rendering into user-allocated memory
22without any sort of window system or operating system dependencies.
23That is, the GL_FRONT colorbuffer is actually a buffer in main memory,
24rather than a window on your display.
25</p>
26
27<p>
28The OSMesa API provides three basic functions for making off-screen
29renderings: OSMesaCreateContext(), OSMesaMakeCurrent(), and
30OSMesaDestroyContext().  See the Mesa/include/GL/osmesa.h header for
31more information about the API functions.
32</p>
33
34<p>
35The OSMesa interface may be used with any of three software renderers:
36</p>
37<ol>
38<li>llvmpipe - this is the high-performance Gallium LLVM driver
39<li>softpipe - this it the reference Gallium software driver
40<li>swrast - this is the legacy Mesa software rasterizer
41</ol>
42
43
44<p>
45There are several examples of OSMesa in the mesa/demos repository.
46</p>
47
48<h1>Building OSMesa</h1>
49
50<p>
51Configure and build Mesa with something like:
52
53<pre>
54configure --enable-osmesa --disable-driglx-direct --disable-dri --with-gallium-drivers=swrast
55make
56</pre>
57
58<p>
59Make sure you have LLVM installed first if you want to use the llvmpipe driver.
60</p>
61
62<p>
63When the build is complete you should find:
64</p>
65<pre>
66lib/libOSMesa.so  (swrast-based OSMesa)
67lib/gallium/libOSMsea.so  (gallium-based OSMesa)
68</pre>
69
70<p>
71Set your LD_LIBRARY_PATH to point to one directory or the other to select
72the library you want to use.
73</p>
74
75<p>
76When you link your application, link with -lOSMesa
77</p>
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