Re: [Mesa3d-users] using osmesa together with nvidia GL implementation

[Viral P. <Vir...@an...>]

It was a while ago that I built Mesa for this purpose, here are some
hints based
on my notes and what I recall, there are several ways to skin a cat so
you may be
able to do the same in other ways.

This is what I did to build things:

....................
make distclean

Edit configs/autoconf.in
    change "GL_LIB = GL" to "GL_LIB = MyMesaGL"
    change "GLU_LIB = GLU" to "GLU_LIB = MyMesaGLU"
    change "GLUT_LIB = GLUT" to "GLUT_LIB = MyMesaGLUT"
    change "OSMESA_LIB = @OSMESA_LIB@" to "OSMESA_LIB = My@OSMESA_LIB@"
    Add "CFLAGS += -DUSE_MGL_NAMESPACE" under the existing CFLAGS def.
    Add "CXXFLAGS += -DUSE_MGL_NAMESPACE" under the existing CXXFLAGS
def.

./configure --prefix=<SOME DIRECTORY> --disable-driglx-direct 
		--enable-gl-osmesa=yes --disable-glw --with-driver=xlib 
		--with-osmesa-bits=32
gmake
....................

This will give you a set of libraries such that MyMesaGLU will be linked

against MyMesaGL and the same for GLUT.

Typically Mesa didn't seem particularly setup to be used as an alternate

linkable gl implementation and the default configurations are meant to
build 
a replacements for the system gl implementation. So you may need to go 
through the headers and check that all symbols are being mangled.

Good luck.

Viral

-----Original Message-----
From: Alex Flint [mailto:ale...@gm...] 
Sent: 17 February 2010 15:54
To: Viral Patel
Cc: mes...@li...
Subject: Re: [Mesa3d-users] using osmesa together with nvidia GL
implementation

Thanks for your help Viral.

I am now having difficulty compiling with USE_MGL_NAMESPACE

$ env CFLAGS=-DUSE_MGL_NAMESPACE ./configure
$ make
...
glxcmds.c:1577: error: 'glXGetCurrentDisplayEXT' aliased to undefined
symbol 'glXGetCurrentDisplay'
glxcmds.c:1728: error: 'glXQueryContextInfoEXT' aliased to undefined
symbol 'glXQueryContext'
glxcmds.c:2174: error: 'glXGetFBConfigAttribSGIX' aliased to undefined
symbol 'glXGetFBConfigAttrib'
glxcmds.c:2178: error: 'glXChooseFBConfigSGIX' aliased to undefined
symbol 'glXChooseFBConfig'
glxcmds.c:2183: error: 'glXGetVisualFromFBConfigSGIX' aliased to
undefined symbol 'glXGetVisualFromFBConfig'
glxcmds.c:3087: error: 'mglXGetProcAddress' aliased to undefined
symbol 'glXGetProcAddressARB'

The docs say that I should add "CFLAGS += -DUSE_MGL_NAMESPACE" to the
relevant config. It seems that configure has added this to
configs/autoconf:
$ grep USE_MGL_NAMESPACE configs/*
configs/autoconf:CFLAGS =  -DUSE_MGL_NAMESPACE -Wall
-Wmissing-prototypes -std=c99 -ffast-math -fno-strict-aliasing \
configs/current:CFLAGS =  -DUSE_MGL_NAMESPACE -Wall
-Wmissing-prototypes -std=c99 -ffast-math -fno-strict-aliasing \

Is this sufficient or should I add it manually to other configs?

Thanks again in advance,
Alex


On Wed, Feb 17, 2010 at 1:24 PM, Viral Patel <Vir...@an...>
wrote:
> Hi Alex,
>
> You can link in both Mesa and Non-Mesa gl implementations, the key is
to
> use
> mesa in mangled mode, such that, when calling into mesa all gl calls
> are:
>
> mgl*
>
> but calling into non-mesa the calls are,
>
> gl*
>
> This either means you need to write all your code twice or preferably
> use function
> pointers/virtual interfaces to reference each implementation.
>
> You will also need to be careful to use mgl calls only when using with
> an OSMesa gl
> context.
>
> What you are currently doing is linking in 2 different libraries with
> the conflicting
> symbols, simplistically the linker is using some functions from mesa
and
> some from
> nvogl.
>
> I would look at the mangled_* headers in mesa, and the mesa doc has a
> section on
> mangling the api entry points.
>
> Hope this helps.
>
> Viral Patel
>
> Ansys Inc,
>
>
> -----Original Message-----
> From: Alex Flint [mailto:ale...@gm...]
> Sent: 17 February 2010 12:27
> To: mes...@li...
> Subject: [Mesa3d-users] using osmesa together with nvidia GL
> implementation
>
> Hi there,
>
> My program is happily linking to the nvidia OpenGL implementation for
> its normal onscreen rendering. I would like within a small part of
> this program to use the offscreen rendering capabilities of OSMesa. If
> I link to both /usr/lib/libGL.so and /usr/lib/libOSMesa.so then I get
> strange results: either my offscreen-rendered images are blank or GL
> crashes, depending on which order I do the linking.
>
> My first question is: is this even supposed to work? If so I will
> investigate further and post much more detailed info about what's
> going wrong.
>
> If not, is there any other way that I can get both 3D acceleration for
> onscreen rendering and (un-accelerated) offscreen rendering working in
> the same binary?
>
> Thanks in advance,
> Alex
>
>
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