Re: [GtkGLExt] gtk_opengl

[Carlos Pereira <jose carlos pereira ist utl pt>]

Hi Ryan,

we had a long discussion about this just weeks ago, on the GTKGLExt 
mailling list (see below one of my posts describing a new version of the 
code you mention, including comments from Javier Jardon, who ported the 
code to GTK 3.0).

In my opinion, there is no excuse for GTK not supporting OpenGL, when 
this support requires less than one hundred lines of C code. Admittedly 
this is for X11 only, but for Windows it  should not be that different...

Ideally GTK developers will include some improved version of this code 
(or equivalent) in the GTK main tree (hello Javier? John?)... Until that 
day arrives, just use it directly on your app...

Carlos
> On 03/23/2014 11:17 PM, Ryan Danbrook wrote:
> Hi,
>
> I came across a mailing list post you made years ago:
> https://mail.gnome.org/archives/gtk-app-devel-list/2010-March/msg00023.html
>
> I downloaded gtk_opengl.tar.gz and was pleased to find it has been updated
> very recently, with compatibility for GTK+ 3.
>
> I just wanted to say thank you for doing this. I've been looking for a way
> to render OpenGL to a GtkDrawingArea for months now, and this helped me
> solve my problem. This is a problem a lot of other people are having as
> well (especially in the SDL community, since it is no longer possible to
> easily render SDL graphical output to a widget). I think you should
> consider making gtk_opengl a more public project, I'm sure there are other
> people out there who would appreciate it as well.
>
> It's funny how our projects are completely different, but have similar
> problems to solve. My project is an NES emulator.
>
> Thanks,
> Ryan
>
>    
Hello everyone, hi Javier, hi John,

I prepared a new edition of this code:
http://www.gamgi.org/gtk_opengl.tar.gz

The (minor) differences are:

1) added a fourth  parameter to gtk_opengl_create (direct rendering or 
rendering through X);

2) back ported to GTK 2 the colormap simplication that Javier introduced 
in the GTK 3 version. The only difference between GTK2 and GTK3 versions 
of gtk_opengl.c is now this (occurring in several functions):

GTK 2:
Display *xdisplay = gdk_x11_drawable_get_xdisplay (drawable);

GTK 3:
GdkDisplay *display = gdk_window_get_display (drawable);
Display *xdisplay = gdk_x11_display_get_xdisplay (display);

3) Added legal notices (this is a overkill but I am trying to make life 
as simple as possible for everyone): The version for GTK 3 is 
distributed under the licenses simplified BSD or LGPL (users choose). 
The version for GTK 2 is distributed under the simplified BSD. The 
rationale is: the GTK team might prefer the LGPL but BSD can be used 
everywhere, including closed source. The simplified BSD is the simplest 
license I could find (the OpenBSD license). The CC0 seems slightly more 
complex...

4) Javier, I added your name to the copyright notice, as you gave a very 
significant contribution to make this code useful.

5) Everything else are cosmetic changes: updated comments, variable 
names, order of functions

6) As a result this new tarball has the following directories (just 
ignore those you don't want):

gtk3_bsd/
gtk3_lgpl/
gtk2_bsd/
gtk2_glext/

This is also explained in the README.

Regards,
Carlos
> On 23 February 2014 23:49, Carlos Pereira
> <jose carlos pereira ist utl pt>  wrote:
> > Sorry for the delay, here is the code I prepared (it contains all
> > the functions needed to run OpenGL on a GTK drawing area):
> >
> > http://www.gamgi.org/gtk_opengl.tar.gz
> > or:
> > http://www.gamgi.ist.utl.pt/gtk_opengl.tar.gz
> >
> > The code is in a single file, gtk_opengl.c, very easy to read, I think.
> > It has 189 lines of C code only, a good part of it are comments and 
> > space
> > lines...
> >
> > I included a directory with two classic examples, distributed by all
> > GtkGLArea and GtkGLExt releases, to show how this code works.
> >
> > I included other directory with the same two examples, this time
> > using GtKGLExt, to make it simpler to compare the two approaches.
> >
> > The code comes with README files and comments, with the most relevant
> > information. A variation of this code has been used since 2010 in a
> > relatively
> > large package without known problems.
> >
> > I want to make it clear that I wrote this code for GTK 2 and the X 
> > Window
> > System.
> > There are a few gdk_x11_* functions, included through<gdk/gdkx.h>, that
> > might be handled differently on GTK 3. These changes, if needed, 
> > *should* be
> > trivial.
> I was curious about this and I ported your "library" and examples to
> GTK+3 (basically all the content of the home_made folder)
> On my testing everything compiles and works perfectly fine :)
> Ive uploaded the code to this repository [1] in case you (or anyone)
> are interested
>
> Regards and thanks for your work!
>
> [1] https://gitorious.org/gtkopengl/gtkopengl/source/master: