Guile OpenGL bindings

Guile OpenGL bindings

[Andy Wingo]

Hi Javier,

Have you had time to think about GL bindings for Guile?  I had been
meaning to do something about it for a long time, and finally got around
to a first hack last week.  Daniel and I are working in this repo:

  https://gitorious.org/guile-figl

The idea is to use the FFI to make a low-level, complete interface, and
then as needed to make higher-level more Scheme-like wrappers.  I also
really wanted documentation, so I munged the upstream docbook into
texinfo and wrote that out into docstrings and .texi files.  The binding
isn't working yet, but maybe soon.  I'd like to avoid C if I can.

Daniel has an FFI-based GLUT wrapper that he is merging in that repo as
well.  Are you interested in joining efforts?  I can add you to the
gitorious project if you like.

Cheers,

Andy
-- 
http://wingolog.org/

Re: Guile OpenGL bindings

[Javier Sancho]

Andy Wingo wrote:
> Hi Javier,

Hi.

> Have you had time to think about GL bindings for Guile?

Not much. I've been a little busy with my first child :-)
Just this week I'm back to thinking about it.

> The idea is to use the FFI to make a low-level, complete interface, and
> then as needed to make higher-level more Scheme-like wrappers.  I also
> really wanted documentation, so I munged the upstream docbook into
> texinfo and wrote that out into docstrings and .texi files.  The binding
> isn't working yet, but maybe soon.  I'd like to avoid C if I can.

Aleix Conchillo is also working with OpenGL and encountered a problem
with glutInit and char**. You can see it at
http://lists.gnu.org/archive/html/guile-devel/2012-07/msg00074.html
Someone mentioned performance issues when using FFI, too.

> Daniel has an FFI-based GLUT wrapper that he is merging in that repo as
> well.  Are you interested in joining efforts?  I can add you to the
> gitorious project if you like.

Well, I can't promise anything, but yes, I'm very interested in this project.

This weekend I'll try to hack a little.

Cheers.

--
Javier Sancho Fernández - http://www.jsancho.org/
Associate Member of the Free Software Foundation - http://www.fsf.org/
Contra el DRM - http://www.defectivebydesign.org/what_is_drm

Re: Guile OpenGL bindings

[Daniel Hartwig]

On 1 February 2013 21:02, Javier Sancho <jsf@jsancho.org> wrote:
> Aleix Conchillo is also working with OpenGL and encountered a problem
> with glutInit and char**. You can see it at
> http://lists.gnu.org/archive/html/guile-devel/2012-07/msg00074.html

Mark's suggestion is spot on, even points out one issue with memory
that I have missed.

It seems that Aleix later moved to a C binding, though I am confident
this can be avoided (c.f. cl-opengl).  Anyway, this function is
working fine in the bindings I have prepared (sans the memory issue).

GLUT bindings cover all functions, but missing constants.  These to
follow shortly.

Andy's work on the sxml side has the GL bindings *almost* running as
well.  I'll look to finish those in the next few days if someone
doesn't beat me to it.

> Someone mentioned performance issues when using FFI, too.

For modern GL programming without glBegin/End, Vertex/Color/Normal,
etc. the performance impact of FFI should be negligable.  There are
few GL calls compared to the volume of data that is passed.

The real critical part will be how the user manipulates their vertex
data, if this is done frequently on the scheme side.  Mapping (typed)
bytevectors, or srfi-4 to gl arrays will help with that, and avoiding
the implicit type conversions that some other bindings perform.

> Well, I can't promise anything, but yes, I'm very interested in this project.

Nice.

Re: Guile OpenGL bindings

[Mark H Weaver]

Javier Sancho <jsf@jsancho.org> writes:
> Someone mentioned performance issues when using FFI, too.

That was me, and I regret emphasizing that.  In a couple of years, when
Guile has native compilation, it is likely that the FFI will be as fast
as C wrappers, maybe even a bit faster.

Anyway, as Knuth wrote, "We should forget about small efficiencies, say
about 97% of the time: premature optimization is the root of all evil",
and he was absolutely right.  Countless projects have been ruined by
premature optimization.

It's far more important to write the cleanest, simplest code that will
get the job done.  Only after determining the hotspots (by profiling)
should you optimize those bits.

Plus, as Daniel Hartwig <mandyke@gmail.com> wrote:

> For modern GL programming without glBegin/End, Vertex/Color/Normal,
> etc. the performance impact of FFI should be negligable.  There are
> few GL calls compared to the volume of data that is passed.
>
> The real critical part will be how the user manipulates their vertex
> data, if this is done frequently on the scheme side.  Mapping (typed)
> bytevectors, or srfi-4 to gl arrays will help with that, and avoiding
> the implicit type conversions that some other bindings perform.

   Regards,
     Mark

Re: Guile OpenGL bindings

[vimml]

Hej,

this all sounds really cool :-)

I hacked a little bit of code to generate C bindings for what is specified in
the glcorearb.h file. I also wrote a small script to extract the gl constants
and define them as scheme variables.
This is all *really* hacky stuff, but if somebody wants to have a lookt at it...

On 21:29 Fri 01 Feb     , Daniel Hartwig wrote:
> The real critical part will be how the user manipulates their vertex
> data, if this is done frequently on the scheme side.  Mapping (typed)
> bytevectors, or srfi-4 to gl arrays will help with that, and avoiding
> the implicit type conversions that some other bindings perform.
I did use r6rs bytevectors (bytevector-ieeee-single-native-ref...) to plow
through my data and it was rather sluggish. It's quite possible that I did
someting terribly wrong, but I went back to do the crunching in C...

On 13:16 Fri 01 Feb     , Andy Wingo wrote:
>   https://gitorious.org/guile-figl
Looking forward to have a look at your code :-)

Happy Hacking,
	Kai :)

Re: Guile OpenGL bindings

[Daniel Hartwig]

On 2 February 2013 04:56,  <vimml@selgrad.org> wrote:
> I hacked a little bit of code to generate C bindings for what is specified in
> the glcorearb.h file. I also wrote a small script to extract the gl constants
> and define them as scheme variables.
> This is all *really* hacky stuff, but if somebody wants to have a lookt at it...

For reference, the canonical source of that information is in a set of
spec files <http://www.opengl.org/registry/#specfiles>.

Re: Guile OpenGL bindings

[Aleix Conchillo Flaqué]

On Fri, Feb 1, 2013 at 4:16 AM, Andy Wingo <wingo@pobox.com> wrote:
> Hi Javier,
>
> Have you had time to think about GL bindings for Guile?  I had been
> meaning to do something about it for a long time, and finally got around
> to a first hack last week.  Daniel and I are working in this repo:
>
>   https://gitorious.org/guile-figl
>
[snip]

These are really good news! Thanks Daniel and Andy!

I stopped working on guile-gl a while ago. I moved from FFI to C
bindings after some messages on the mailing list as Javier pointed.
But after this email I will definitely not retake the work. It doesn't
make a lot of sense to duplicate efforts, specially if the people that
take the effort have more experience.

So, great news!

Aleix