121 lines
4.1 KiB
Plaintext
121 lines
4.1 KiB
Plaintext
Haiku OpenGL kit developers introduction
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The Haiku OpenGL kit is made up of the folwing pieces:
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* The "OpenGL Kit" aka libGL.so and supporting libraries.
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This is what the user applications interact with.
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* The "OpenGL Add-ons" (which do the real work)
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These are chosen by the OpenGL kit and utilized
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In the traditional BeOS sense, the OpenGL Add-ons are the
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vendor provided OpenGL drivers. This actually doesn't
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mesh well with the current open source OpenGL stack.
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Our "OpenGL Add-ons" are really wrappers around Mesa
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and Gallium code. We gain greater OS control of OpenGL
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rendering with the drawback of increased work overall.
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The OpenGL Add-ons call private Mesa functions, thus
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we get no compatibility saftey net between Mesa versions.
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Our Gallium connecting Add-ons could actually fit into
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the upstream Mesa / Gallium project, however this would
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cause complications in the build process (linking in
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OpenGL and all of it's libraries into a small number of
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shared libraries is not really what the Mesa project
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designs it's stack for. Several symbol collisions exist
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when trying to link libmesa and libgallium together for
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example)
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Mesa drivers are the classical Mesa software rasterizers
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Gallium drivers are the new-school software drivers.
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**********
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Mesa versions
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The Haiku project uses two different versions of Mesa.
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* Mesa 7.8.2 for gcc2 OpenGL Add-ons
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* Mesa 9.0.1+ for gcc4 OpenGL Add-ons.
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The reasoning behind this is that any version of Mesa
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above 7.8.2 will require a *massive* porting effort to
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make it compile under gcc2. Given this fact, it makes
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sense to bump the gcc2 version of Mesa as far as it will
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go and set it there statically. Think of Mesa 7.8.2
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as the "stable" version Haiku R1 will use :)
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Hardware 3D rendering and llvm-based software rendering
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will never work for legacy gcc2 applications. Period.
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However! If you're running a gcc2 hybrid version of
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Haiku, llvm or hardware based rendering should be possible
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on gcc4 applications.
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It is *essential* to upgrade our build Mesa packages
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with the latest release Mesa versions. If we fall too
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far behind the update gets extremely tricky as functions
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inside Mesa and Gallium change at a fast pace.
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**********
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gcc2 OpenGL kit
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The following process occurs in order to generate the
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gcc2 (Mesa 7.8.2) OpenGL kit:
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* Some kind soul compiles a Mesa optional package on a
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gcc2 Haiku system with the bep on haikuports. This
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gets uploaded to Haiku-files and the package name
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/ version gets updated as in the BuildFeatures jam
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build script.
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- The bep generally applies a few minimal patches to
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Mesa 7.8.2 and compiles it. Then it rounds up all of
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the headers and static libraries and throws them into
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a .zip for the build
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* Someone starts a gcc2 Haiku build. The build process pulls
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down the Mesa optional package above and links the needed
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parts into libGL and the swrast_legacy OpenGL add-on
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**********
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gcc4 OpenGL kit
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The following process occurs in order to generate the
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gcc4 (Mesa 9.0.1+) OpenGL kit:
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* Some kind soul compiles a Mesa optional package on a
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gcc4 Haiku system with the bep on haikuports. This
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gets uploaded to Haiku-files and the package name
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/ version gets updated as in the BuildFeatures jam
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build script.
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- The kind soul also needs to install the LLVM Optional
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build package on his build machine *before* compiling
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the Mesa bep. (unless he or she doesn't want llvmpipe
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rendering)
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- The bep for Mesa 9.0.1+ doesn't apply too many patches as
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Haiku build fixes are accepted upstream.
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- The bep rounds up all of the headers and static
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libraries and throws them into a .zip for the build
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* Someone starts a gcc4 Haiku build. The build process pulls
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down the Mesa optional package above and links the needed
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parts into libGL and OpenGL add-ons.
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- If the user didn't link in LLVM, he can disable the LLVM
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dependencies in the OpenGL kit Jamfile. swpipe will
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automagically fall back to softpipe rendering
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- The build system will download the LLVM optional package
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and link it into any OpenGL add-ons that need it.
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!! The LLVM optional package needs to match the LLVM
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binaries on the machine which compiled Mesa
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!!
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