Re: NSOpenGL

[Thomas Gamper]

Hi!


> thank you for that rework.
It's barely a rework, I didn't change the structure of the code, I just 
tried to fix some issues so that it would work for me. I tried to get 
some idea how the gnustep-backends work, but didn't come really far. So 
I still fear I screwed up something without knowing.

> I just submitted these changes to SVN, with a
> slight bit of rework and reformatting.
Thanks.
> What I don't like about the current code (not just your changes) is that
> it is still unclear to me, whether the difference between the minor
> releases of GLX is a compile time or run time difference.
It's a run time difference since it depends on the driver.
> Are all the
> new functions really present in a GLX version < 1.3? If not, then we
> should protect these calls in the code with #ifdefs.
The new functions  fo glx 1.3 are just those using GLXFBConfig 
(glXMakeContextCurrent,glXCreateNewContext,glXGetVisualFromFBConfig,glXGetFBConfigAttrib,glXChooseFBConfig)
> Also the usage of the union in pixel format looks strange, we need to
> read what was set, not what suits the current GLX version.
Could you explain in detail, please?

> Sure this
> versions wont change during the runtime of the program, still it looks
> wrong. This is why I moved all of the reference to the union into the
> separate file. A next step would be to clean up the usage here.
> As you are now creating a separate drawable, isn't the deallocation of
> that drawable needed? I put in a FIXME, where I think this call is
> missing.
You're right.
> Again it is only needed for the newer GLX release.
I'm not sure about that. I did all this work because I wasn't able to 
get an opengl pixelformat and context with an alpha channel, stencil 
buffer, and so on.  I looks like the cause was the X Window's colormap 
not being able to support the pixelformat. Maybe we have to allocate a 
separate drawable for older glx versions too, to be able to support all 
pixel formats.
> To me all these files look like work in progress, hopefully you keep on
> working on them.
Yeah, all of this stuff looks like it was done rather hasty back in 
2002, and I think the X-Server opengl drivers weren't rather cooperative 
at that time ( that doesn't mean they are cooperative today). I still 
need to add some pixelformat stuff (multisample support) and will 
continue to work on this code. I'm using GNUstep for my diploma thesis, 
and I have written a lot of code already, but I didn't the test 
GNUstep's opengl support really well until recently. Basically I HAD to 
fix this, otherwise I would have lost more than 2 month of work :)

Keep up your good work on GNUstep :)

Cheers
TOM
> Cheers,
> Fred
>
>
> Thomas Gamper wrote:
> > Recently I was using NSOpenGLView and fixed a couple of bugs in
> > gnustep-back 0.12.0 ( I believe newer versions have the same issues):
> >
> > - XGGLPixelFormat handling was confusing glx parameters, since glx 1.3
> > has some different parameters than earlier versions of glx
> > - XGGLContext did not create the rendering context, the x window, and
> > the glx window with the same Visual
> > - XGGLContext did not create a colormap for the x window (which has to
> > use the same Visual too)
> >
> > The attached files fix this issues. I tried to follow the gnustep
> > coding style but I am not sure if I succeeded :)
> >
> > Please let me know if there are any change requests.
> > I am not subscribed to the list, so please CC me.