[Mesa-dev] Meson mesademos (Was: [RFC libdrm 0/2] Replace the build system with meson)
Dylan Baker
dylan at pnwbakers.com
Tue Mar 28 21:37:28 UTC 2017
Quoting Jose Fonseca (2017-03-28 13:45:57)
> On 28/03/17 21:32, Dylan Baker wrote:
> > Quoting Jose Fonseca (2017-03-28 09:19:48)
> >> On 28/03/17 00:12, Dylan Baker wrote:
> >>> Quoting Jose Fonseca (2017-03-27 09:58:59)
> >>>> On 27/03/17 17:42, Dylan Baker wrote:
> >>>>> Quoting Jose Fonseca (2017-03-27 09:31:04)
> >>>>>> On 27/03/17 17:24, Dylan Baker wrote:
> >>>>>>> Quoting Jose Fonseca (2017-03-26 14:53:50)
> >>>>>>>> I've pushed the branch to mesa/demos, so we can all collaborate without
> >>>>>>>> wasting time crossporting patches between private branches.
> >>>>>>>>
> >>>>>>>> https://cgit.freedesktop.org/mesa/demos/commit/?h=meson
> >>>>>>>>
> >>>>>>>> Unfortunately, I couldn't actually go very far until I hit a wall, as
> >>>>>>>> you can see in the last commit message.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> The issue is that Windows has no standard paths for dependencies
> >>>>>>>> includes/libraries (like /usr/include or /usr/lib), nor standard tool
> >>>>>>>> for dependencies (no pkgconfig). But it seems that Meson presumes any
> >>>>>>>> unknown dependency can be resolved with pkgconfig.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> The question is: how do I tell Meson where the GLEW headers/library for
> >>>>>>>> MinGW are supposed to be found?
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> I know one solution might be Meson Wraps. Is that the only way?
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> CMake makes it very easy to do it (via Cache files as explained in my
> >>>>>>>> commit message.) Is there a way to achieve the same, perhaps via
> >>>>>>>> cross_file properties or something like that?
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> Jose
> >>>>>>>
> >>>>>>> I think there are two ways you could solve this:
> >>>>>>>
> >>>>>>> Wraps are probably the most generically correct method; what I mean by that is
> >>>>>>> that a proper wrap would solve the problem for everyone, on every operating
> >>>>>>> system, forever.
> >>>>>>
> >>>>>> Yeah, that sounded a good solution, particularly for windows where's so
> >>>>>> much easier to just build the dependencies as a subproject rather than
> >>>>>> fetch dependencies from somewhere, since MSVC RT versions have to match
> >>>>>> and so.
> >>>>>>
> >>>>>> > That said, I took a look at GLEW and it doesn't look like a
> >>>>>>> straightforward project to port to meson, since it uses a huge pile of gnu
> >>>>>>> makefiles for compilation, without any autoconf/cmake/etc. I still might take a
> >>>>>>> swing at it since I want to know how hard it would be to write a wrap file for
> >>>>>>> something like GLEW (and it would probably be a pretty useful project to wrap)
> >>>>>>> where a meson build system is likely never going to go upstream.
> >>>>>>
> >>>>>> BTW, regarding GLEW, some time ago I actually prototyped using GLAD
> >>>>>> instead of GLEW for mesademos:
> >>>>>>
> >>>>>> https://cgit.freedesktop.org/~jrfonseca/mesademos/log/?h=glad
> >>>>>>
> >>>>>> I find GLAD much nicer that GLEW: it's easier to build, it uses upstream
> >>>>>> XML files, it supports EGL, and it's easy to bundle.
> >>>>>>
> >>>>>> Maybe we could migrate mesademos to GLAD as part of this work instead of
> >>>>>> trying to get glew "mesonfied".
> >>>>>>
> >>>>>>> The other option I think you can use use is cross properties[1], which I believe
> >>>>>>> is the closest thing meson has to cmake's cache files.
> >>>>>>>
> >>>>>>> I've pushed a couple of commits, the last one implements the cross properties
> >>>>>>> idea, which gets the build farther, but then it can't find the glut headers,
> >>>>>>> and I don't understand why, since "cc.has_header('GL/glut')" returns true. I
> >>>>>>> still think that wraps are a better plan, but I'll have to spend some time today
> >>>>>>> working on a glew wrap.
> >>>>>>>
> >>>>>>> [1] https://github.com/mesonbuild/meson/wiki/Cross-compilation (at the bottom
> >>>>>>> under the heading "Custom Data")
> >>>>>>
> >>>>>> I'm running out of time today, but I'll try to take a look tomorrow.
> >>>>>>
> >>>>>> Jose
> >>>>>>
> >>>>>
> >>>>> I'd had a similar thought, but thought of libpeoxy? It supports the platforms we
> >>>>> want, and already has a meson build system that works for windows.
> >>>>
> >>>> I have no experience with libepoxy. I know GLAD is really easy to
> >>>> understand, use and integrate. It's completly agnostic to toolkits like
> >>>> GLUT/GLFW/etc doesn't try to alias equivalent entrypoints, or anything
> >>>> smart like libepoxy.
> >>>>
> >>>> In particular I don't fully understand libepoxy behavior regarding
> >>>> wglMakeCurrent is, and whether that will create problems with GLUT,
> >>>> since GLUT will call wglMakeCurrent..
> >>>>
> >>>>
> >>>> Jose
> >>>
> >>> Okay, I have libepoxy working for windows. I also got libepoxy working as a
> >>> subproject, but it took a bit of hacking on their build system (there's
> >>> some things they're doing that make them non-subproject safe, I'll send patches
> >>> and work that out with them.
> >>>
> >>> https://github.com/dcbaker/libepoxy.git fix-suproject
> >>
> >> Thanks.
> >>
> >> GLEW is not the only one case though. There's also FREEGLUT. So we
> >> can't really avoid the problem of external windows binaries/subprojects.
> >>
> >> So I've been thinking, and I suspect is better if first get things
> >> working with binary GLEW / FREGLUT projects, then try the glew ->
> >> libepoxy in a 2nd step, so there's less to take in to merge meson into
> >> master.
> >>
> >>> Clone that repo into $mesa-demos-root/subprojects and things should just work,
> >>> or mostly work. I got epoxy compiling, but ran into some issues in the mingw glu
> >>> header.
> >>>
> >>> Dylan
> >>
> >> I'm pretty sure the problem with MinGW glu is the lack of windows.h. We
> >> need to do the same as CMakeLists.txt snippet quoted below.
> >>
> >> I'm running out of time today, but I'll look into porting this over to
> >> meson tomorrow if you don't beat me to it.
> >>
> >> Jose
> >>
> >>
> >>
> >> if (WIN32)
> >> # Nobody likes to include windows.h:
> >> # - Microsoft's GL/gl.h header depends on windows.h but doesn't
> >> include it;
> >> # - GLEW temporarily defines the necessary defines but
> >> undefines them later
> >> # - certain GLUT distributions don't include it;
> >> # - most of our programs are meant to be portable so don't
> >> include it.
> >> #
> >> # We could try to replicate the windows.h definitions required by
> >> # GL/gl.h, but the build time savings don't compensate the constant
> >> # headaches that brings, so instead we force windows.h to be
> >> included
> >> # on every file.
> >> if (MSVC)
> >> add_definitions (-FIwindows.h)
> >> else (MSVC)
> >> add_definitions (--include windows.h)
> >> endif (MSVC)
> >>
> >> # Don't define min/max macros
> >> add_definitions (-DNOMINMAX)
> >>
> >> # MSVC & MinGW only define & use APIENTRY
> >> add_definitions (-DGLAPIENTRY=__stdcall)
> >>
> >> link_libraries (winmm)
> >> endif (WIN32)
> >>
> >
> > Okay, I got things compiling and sorta working with mingw (tested with wine,
> > so...) and libepoxy. You might be right that the epoxy work is something that we
> > should do separately, I may try to write a freeglut wrap, it looks a bit more
> > straight forward than glew.
>
> I've been pondering on this further, and I wonder if a good compromise a
> subproject for glew/freeglut, that instead of building those said
> dependencies, would simply fetch and unpack the files in a build subdir,
> and would setup the meson dependency object (ie, path to includes, path
> to libs.)
>
> For example, the freeglut project would download the windows binaries,
> 32 or 64 bits based on the target build, perhaps checksum them, unpack,
> etc.
>
> This would have the feel of a wrap, without the headaches of actually
> porting the dependency to meson. (Nothing prevent us of doing that in
> the long term thought. But it would simplify things in the short term.)
>
> We could host the binaries somewhere in freedesktop.org too for
> protecting against broken urls etc.
>
> Jose
That might be a viable option too. I'm still going to have a go at freeglut, it
should be pretty easy to do, and getting it in the wrapdb would probably be
useful.
Dylan
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