Re: [GtkGLExt] Fwd: Re: GtkGlExt & GTK3

[Norman Goldstein <normvcr telus net>]

Carlos, I am not an OpenGL expert.  I just wrote my first OpenGL code, 
based on the SigGraph video "An Introduction to OpenGL Progranmming".  
It uses a vertex and fragment shader to put put up an orientable cube on 
the screen.  I ported this to Gtk2GlExtMM, and I don't see how GTK could 
be offering a better interface.  From what I saw, GTK is offering a 
fully functional window, allowing for widgets, and an OpenGL region into 
which to write.  I did not feel encumbered in any way, nor do I think 
the efficiency of the code was impeded.  But, I have little experience 
in this field.

How would GTK need to be upgraded to do OpenGL better?  How would it be 
better?
-- More efficient at run-time?
-- More flexibility for the programmer?
-- Allow a fuller OpenGL functionality?

I am asking out of curiosity, and am not presuming to be arguing against 
what you have said.

Thank you.





On 02/11/2014 12:23 PM, Carlos Pereira wrote:
> > gtk 3 does support OpenGL. With clutter and cogl you can integrate plain
> > OpenGL into your application. Maybe it's not as smooth as as Qt's OpenGl
> > widget, but it is better to use than this abandoned GtkGlExt.
> I am sorry this is just not true. As far as I can see Gtk 3 does not 
> support OpenGL. Like Gtk 2. Like Gtk 1.
>
> This is so painfully obvious that it really hurts. Supporting OpenGL 
> is not to build a new API, a new toolkit, a new software layer between 
> user code and OpenGL (or even worse, to write a poor replacement for 
> OpenGL).
>
> I have been in the Gtk developers list since 1999, every 5 years we 
> come again to this issue, to no avail. After almost 15 years watching 
> Gtk developers telling nonsense about OpenGL, I came to the conclusion 
> that Gtk developers don't even understand the issue. It is mildly 
> offensive to ask OpenGL programmers to throw away their optimized 
> OpenGL code and replace it by some clutter API that translates to... 
> OpenGL code!
>
> There are hundreds of books about OpenGL, please buy one and learn 
> OpenGL before posting these ridiculous statements.
>
> All that is needed to bridge Gtk 2 and OpenGL under X11 are about 250 
> lines of C code. I know because I distribute two versions of my 
> package, one uses GtkGLExt, the other uses my own code. If you are 
> really serious about this, I can point you to these packages and 
> explain in detail the relevant C code. And I am not even an expert, I 
> came to this code reading all I could about this...
>
> We have been asking for 15 years to include something like these 250 
> lines of code, that is ALL that is needed to bridge GtK and OpenGL 
> (some of this code is specific for the X Window System - for Wayland, 
> Windows and Mac OS X you will need some slightly different code). Even 
> these 250 lines, many are comments and space lines... This is so 
> ridiculous...
>
> Carlos

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