[haiku-commits] haiku: hrev45213 - docs/develop/opengl
- From: kallisti5@xxxxxxxxxxx
- To: haiku-commits@xxxxxxxxxxxxx
- Date: Sun, 27 Jan 2013 23:47:19 +0100 (CET)
hrev45213 adds 1 changeset to branch 'master'
old head: f763771d2a86db02db16862c71f4f76fed898b34
new head: 9a5c1309d70f457e82f0d20201478514447a5990
overview: http://cgit.haiku-os.org/haiku/log/?qt=range&q=9a5c130+%5Ef763771
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9a5c130: doc: Add some OpenGL kit documentation
* Reduce bus factor.. this stuff is complex.
( I blame the developer who wrote it :\ )
[ Alexander von Gluck IV <kallisti5@xxxxxxxxxxx> ]
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Revision: hrev45213
Commit: 9a5c1309d70f457e82f0d20201478514447a5990
URL: http://cgit.haiku-os.org/haiku/commit/?id=9a5c130
Author: Alexander von Gluck IV <kallisti5@xxxxxxxxxxx>
Date: Sun Jan 27 22:46:09 2013 UTC
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2 files changed, 120 insertions(+)
docs/develop/opengl/openGLkit_Jan-2013.png | Bin 0 -> 70155 bytes
docs/develop/opengl/readme | 120 +++++++++++++++++++++++++
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diff --git a/docs/develop/opengl/openGLkit_Jan-2013.png
b/docs/develop/opengl/openGLkit_Jan-2013.png
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diff --git a/docs/develop/opengl/readme b/docs/develop/opengl/readme
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+Haiku OpenGL kit developers introduction
+
+The Haiku OpenGL kit is made up of the folwing pieces:
+
+* The "OpenGL Kit" aka libGL.so and supporting libraries.
+ This is what the user applications interact with.
+
+* The "OpenGL Add-ons" (which do the real work)
+ These are chosen by the OpenGL kit and utilized
+
+In the traditional BeOS sense, the OpenGL Add-ons are the
+vendor provided OpenGL drivers. This actually doesn't
+mesh well with the current open source OpenGL stack.
+
+Our "OpenGL Add-ons" are really wrappers around Mesa
+and Gallium code. We gain greater OS control of OpenGL
+rendering with the drawback of increased work overall.
+The OpenGL Add-ons call private Mesa functions, thus
+we get no compatibility saftey net between Mesa versions.
+
+Our Gallium connecting Add-ons could actually fit into
+the upstream Mesa / Gallium project, however this would
+cause complications in the build process (linking in
+OpenGL and all of it's libraries into a small number of
+shared libraries is not really what the Mesa project
+designs it's stack for. Several symbol collisions exist
+when trying to link libmesa and libgallium together for
+example)
+
+Mesa drivers are the classical Mesa software rasterizers
+Gallium drivers are the new-school software drivers.
+
+
+**********
+Mesa versions
+
+The Haiku project uses two different versions of Mesa.
+
+ * Mesa 7.8.2 for gcc2 OpenGL Add-ons
+ * Mesa 9.0.1+ for gcc4 OpenGL Add-ons.
+
+The reasoning behind this is that any version of Mesa
+above 7.8.2 will require a *massive* porting effort to
+make it compile under gcc2. Given this fact, it makes
+sense to bump the gcc2 version of Mesa as far as it will
+go and set it there statically. Think of Mesa 7.8.2
+as the "stable" version Haiku R1 will use :)
+
+Hardware 3D rendering and llvm-based software rendering
+will never work for legacy gcc2 applications. Period.
+
+However! If you're running a gcc2 hybrid version of
+Haiku, llvm or hardware based rendering should be possible
+on gcc4 applications.
+
+It is *essential* to upgrade our build Mesa packages
+with the latest release Mesa versions. If we fall too
+far behind the update gets extremely tricky as functions
+inside Mesa and Gallium change at a fast pace.
+
+
+**********
+gcc2 OpenGL kit
+
+The following process occurs in order to generate the
+gcc2 (Mesa 7.8.2) OpenGL kit:
+
+* Some kind soul compiles a Mesa optional package on a
+ gcc2 Haiku system with the bep on haikuports. This
+ gets uploaded to Haiku-files and the package name
+ / version gets updated as in the BuildFeatures jam
+ build script.
+
+ - The bep generally applies a few minimal patches to
+ Mesa 7.8.2 and compiles it. Then it rounds up all of
+ the headers and static libraries and throws them into
+ a .zip for the build
+
+* Someone starts a gcc2 Haiku build. The build process pulls
+ down the Mesa optional package above and links the needed
+ parts into libGL and the swrast_legacy OpenGL add-on
+
+
+**********
+gcc4 OpenGL kit
+
+The following process occurs in order to generate the
+gcc4 (Mesa 9.0.1+) OpenGL kit:
+
+* Some kind soul compiles a Mesa optional package on a
+ gcc4 Haiku system with the bep on haikuports. This
+ gets uploaded to Haiku-files and the package name
+ / version gets updated as in the BuildFeatures jam
+ build script.
+
+ - The kind soul also needs to install the LLVM Optional
+ build package on his build machine *before* compiling
+ the Mesa bep. (unless he or she doesn't want llvmpipe
+ rendering)
+
+ - The bep for Mesa 9.0.1+ doesn't apply too many patches as
+ Haiku build fixes are accepted upstream.
+
+ - The bep rounds up all of the headers and static
+ libraries and throws them into a .zip for the build
+
+* Someone starts a gcc4 Haiku build. The build process pulls
+ down the Mesa optional package above and links the needed
+ parts into libGL and OpenGL add-ons.
+
+ - If the user didn't link in LLVM, he can disable the LLVM
+ dependencies in the OpenGL kit Jamfile. swpipe will
+ automagically fall back to softpipe rendering
+
+ - The build system will download the LLVM optional package
+ and link it into any OpenGL add-ons that need it.
+
+ !! The LLVM optional package needs to match the LLVM
+ binaries on the machine which compiled Mesa
+ !!
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