[lsb-discuss] Specification of OpenGL interfaces

[Wichmann, Mats D]

lsb-discuss-bounces at lists.linux-foundation.org wrote:
> On Wed, Sep 19, 2007 at 07:12:26AM -0700, Wichmann, Mats D wrote:
>> lsb-discuss-bounces at lists.linux-foundation.org wrote:
>>> LSB refers the "OpenGL Application Binary Interface for Linux" [1]
>>> regarding all OpenGL interfaces.
>>> 
>>> [1] http://oss.sgi.com/projects/ogl-sample/ABI/
>>> 
>>> But this link does not give any hint about usage of OpenGL
>>> interfaces. 
>>> 
>>> I have found several places containing some descriptions:
>>> 
>>> http://www.opengl.org/documentation/specs/man_pages/hardcopy
>>> http://www.opengl.org/sdk/docs/man/
>>> http://www.opengl.org/documentation/specs/
>>> 
>>> The question is which of them (or may be something else) we will
>>> make the "LSB-canonical" description of OpenGL interfaces?
> 
>    The formal definition of OpenGL is the API Specification, which is
> reached from www.opengl.org/documentation/specs/ . For a fully
> realized OpenGL implementation, this needs to be combined with the
> OpenGL Shading
> Language Specification (for OpenGL 2.0 or later implementations), the
> GLX 1.4 Specification (GLX is included in libGL), and the GLU 1.3
> Specification (libGLU). The C-language API bindings are encoded in the
> headers under www.opengl.org/registry/ - the core OpenGL Specification
> defines bindings in an abstract C-like syntax.
> 
>    The man pages are not canonical. Also, the
> documentation/specs/man_pages/hardcopy link you mention is, or at
> least should be dead - the up-to-date man pages are in sdk/docs/man/ .
> 
>    Which specification document to use depends on which version(s) of
> the API LSB will mandate runtime and linktime support for. These do
> not have to necessarily be the same API version; between the
> loadable driver
> model and the desire to support older hardware, the appropriate course
> of action is probably to mandate OpenGL 2.1 support at linktime,
> possibly including some ARB-approved OpenGL extensions as
> well, but only
> OpenGL 1.4 or 1.5 at runtime. It depends on how much older graphics
> hardware you want to exclude. 
> 
>    I'm willing (as the original author of the ABI) to help out with
> this. If people want to update the ABI document as a standalone thing
> and continue to refer to it from the LSB spec, I will own that. The
> ABI needs to be moved off of oss.sgi.com in any event, since SGI is
> completely out of the graphics business and there's nobody
> left there to
> maintain that content. If it continues as a standalone
> document, I don't
> know what the approval process would be for an update.
> 
>    If people want to fold it into LSB documents, someone else will
have
> to do the writing - but I'm willing to advise and liase with the
> OpenGL ARB working group of Khronos as needed.
> 
>    This topic has come up many times before and always ground to a
halt
> for lack of participation after the initial query to the LSB list. The
> major decisions to be made are only to figure out what API versions to
> support. Is there an LSB process for calling a vote on decisions like
> these? It is not hard to get data from NVIDIA, AMD/ATI, Intel, and
> Tungsten Graphics / Mesa on how much hardware cannot support a
> particular version of the API, and that could inform the decision.

Hey, we actually only care about Intel hardware :-) :-) :-)
(for some very small subset of "we")

I think this list is the place for the discussion, and if 
we can converge on a real proposal, there's a mechanism for
approving it, yes.

And if we need a home for a "Linux ABI", the Linux Foundation
seems a pretty reasonable place even if that continues to be
something that's slightly outside the LSB as it was before.

-- mats