Building OpenGL from source

[jose isaias cabrera]

show-off! :-)

Just kidding.  :-)  I wish you well and let us know how that goes.

jic

----- Original Message ----- 
From: "Zieg, Mark" <mark.zieg@lmco.com>
To: <cygwin-xfree@cygwin.com>
Sent: Tuesday, June 07, 2005 3:30 PM
Subject: Building OpenGL from source


> Hello,
> 
> Pardon if this is an easy one, but I've been looking at it for a few
> days and haven't found an "easy" solution.  If anyone can issue me a few
> adroit pointers (or kicks), I'd be most grateful.
> 
> PROBLEM
> -------
> 
> I need to be able to build and run an OpenGL implementation from source
> on Windows.  Performance isn't an issue, so it doesn't need to have any
> hardware acceleration, but I need to be able to tweak specific equations
> and constants within the source code.
> 
> OBSERVATIONS
> ------------
> 
> It looks like the default Cygwin OpenGL libraries are basically just
> pass-throughs to the pre-compiled Microsoft implementation; is that
> correct?  Since MS probably isn't about to open up the source to their
> version, I went looking for open-source implementations.  SGI's
> ogl-sample and the Mesa3D version both looked promising; perhaps
> Chromium if neither of those pan out.
> 
> However, I'm finding it's "easier said than done" to get one of those
> compiling and linked into Cygwin's X11R6 installation.  For instance,
> Mesa3D doesn't seem to come with a "cygwin" configuration.  I hacked one
> from the provided "linux-static" version and was able to compile, but
> the teapot demo coredumps on its first(?) call to glGetString:
> 
>  LOG INFO   :  teapot: Teapot V1.2
>  LOG INFO   :  teapot: Written by David Bucciarelli (tech.hmw@plus.it)
>  LOG INFO   :  teapot: calling glutInit...
>  LOG INFO   :  teapot: calling inittextures...
>  LOG TRACE  :    inittextures: [entering]
>  LOG INFO   :      inittextures: glGenTextures...
>  LOG INFO   :      inittextures: glBindTexture...
>  LOG INFO   :      inittextures: glPixelStorei...
>  LOG INFO   :      inittextures: LoadRGBMipmaps...
>  LOG TRACE  :        LoadRGBMipmaps: [entering]
>  LOG TRACE  :            LoadRGBMipmaps2: [entering]
>  LOG INFO   :              LoadRGBMipmaps2: calling tkRGBImageLoad:
> ../images/tile.rgb
>  LOG TRACE  :                tkRGBImageLoad: [entering]
>  LOG TRACE  :                tkRGBImageLoad: [returning]
>  LOG INFO   :              LoadRGBMipmaps2: checking that image was
> returned
>  LOG INFO   :              LoadRGBMipmaps2: determining format from
> number of components
>  LOG INFO   :              LoadRGBMipmaps2: looks like RGB
>  LOG INFO   :              LoadRGBMipmaps2: calling gluBuild2DMipmaps
>  LOG INFO   :                gluBuild2DMipmaps: calling closestFit...
>  LOG INFO   :                  closestFit: start
>  LOG INFO   :                  closestFit: calling
> glGetString(GL_VERSION)
>  Segmentation fault (core dumped)
> 
> I wasn't sure where that was coming from, so I temporarily set that path
> aside and tried looking at the SGI ogl-sample build instructions.  It
> seemed to state that, like it or not, I was probably going to have to
> build X11 from scratch if I wanted to change OpenGL implementations.  
> 
> So then I took a full CVS checkout of Xorg (per
> http://x.cygwin.com/docs/cg/prog-obtaining-source.html) and built it.
> That went surprisingly smooth (great job, maintainers!), but all my
> teapot examples still seemed to want to link against
> /usr/lib/w32api/*32.a, which I gather are not touched by the Xorg
> installation.  I tried pointing my teapot app to /usr/X11R6/lib, which
> has these intriguingly named libraries:
> 
>  libGL-1.dll.a
>  libGL.dll.a
>  libGLU-1.dll.a
>  libGLU.dll.a
>  libGLw.a
> 
> However, trying to link against those spat out lots of undefined
> references:
> 
>  make[1]: Entering directory `/home/ziegm/opengl/teapot'
>  g++ teapot.o -L/usr/X11R6/lib -lglut -lGLU -lGL -o teapot
>  teapot.o:teapot.cpp:(.text+0xd2): undefined reference to
> `_glClearColor@16'
>  teapot.o:teapot.cpp:(.text+0xe1): undefined reference to
> `_glShadeModel@4'
>  teapot.o:teapot.cpp:(.text+0x11d): undefined reference to
> `_glMaterialfv@12'
>  teapot.o:teapot.cpp:(.text+0x159): undefined reference to
> `_glLightfv@12'
>  teapot.o:teapot.cpp:(.text+0x1fe): undefined reference to
> `_glEnable@4'
>  teapot.o:teapot.cpp:(.text+0x27c): undefined reference to
> `_gluLookAt@72'
>  ...etc
> 
> My assumption (!) from those results is that the full Xorg build is
> still "noticing" that I'm on Cygwin/Windows, and is therefore
> "helpfully" linking its own code against the w32api/MS libraries.  (I
> really don't understand enough about this process to confirm or refute
> that theory, however.)
> 
> However, I do see that the Mesa code shipped with Xorg under "extras" is
> indeed being compiled and linked into an "libOSMesa.dll.a" archive.
> However, linking against that didn't resolve any of the above linker
> errors.  To try to confirm whether these files were even being used, I
> added a bunch of "printf's" to extras/Mesa/src/mesa/*/*light.c
> (apparently symlinked to lib/GL/mesa and programs/Xserver/GL/mesa), yet
> running teapot (linked against /usr/lib/w32api) generated nary a
> message.
> 
> Am I even on the right track?  Is there an easier way to do this?  If
> you needed to intercept and customize a few specific OpenGL functions
> (say, the lighting model), under Windows, preferably via Cygwin, how
> would you go about it?
> 
> Thank you for any help you may provide,
> 
> Mark Zieg
> 
>