[osg-users] OSG in Gtk3 GLArea

[Robert Osfield]

HI ?

On 4 June 2018 at 15:31, Mean Taipan wrote:
> Thanks for the reply.  Don't know what I said to deserve the introductory put-down, but anyway if my only reasonable choice is to

I like many others use the osg-users mailing list that is paired with
the forum, so we get your full Mean Taipan and email address.  It's
your choice what you put in your handle but you should be aware that
it comes across as really immature.  Ask yourself, how do you
introduce yourself in person when you plan to have a respectful
conversion with someone.  Do you start off by being childish and
disrespectful?

This is an important issue because I have to handle support for many
hundreds of people (tens of thousands over the years), when people
start off with the a tone that id not mature it can lead to others not
being respectful or constructive.  I've been an open source project
lead for 18 years, I know the types of things that lead to flame feats
and un constructive discussions.  This is why I raise the flag on
childish/disrespectful handles and try to establish the right tone
early on - we are adults here who just want to write good code.

> then please clarify a few things:
>
> There are no direct openGL calls in my app; I rely on OSG to render the models and that's it (and of course I don't know what Gtk does under the covers).  So I'm not sure how using just shaders in my program is relevant.  Aren't there default ones?  Do I need to enable some as a replacement for where I used to glBegin/End?  If so, where is the best place to start reading about it?

Independent from the GL core profile you absolutely should replace all
cases of glBeing/glEnd in your code, it's emulated at best by the
driver, it's very slow, and not supported at all under GLES and modern
GL.  Modern OSG doesn't touch it either.  glBein/glEnd is from the
90's, it's use has long been discouraged.

> I did build the latest stable OSG from source, but I would appreciate if you could point to the appropriate documentation for "building against GLCore from scratch".  Hopefully it's just some magic -D compiler options.

Simply set the OPENGL_PROFILE when invoking the OSG.

cmake -DOPENGL_PROFILE=GLCORE .
make


> At present, I am actually trying a work-around which is to render to a texture or pbuffer, with a context created by OSG, then basically copy that over to the normal 2D engine like Cairo.  Inefficient, but it may work OK for us since the 3D display is not full-screen.

> Regards,
> John (since my randomly selected pseudonym makes it impossible for you to treat me as anything but an idiot, please, go ahead and call me 'John'.)

Or just use you own real first name, I much prefer honesty over
"games" and "fronts".  Treat people like you would a family, friend or
colleague, just treat them with respect, starting off with some façade
is really just a form of deceit. Do I want your whole life story? No.
A simple human first name, even better your own first name is perfect.

Cheers,
Robert.