Re: Questions about "configure" and "native graphics"

[John W. Eaton]

On 04/21/2015 09:59 AM, Julien Bect wrote:
> Le 21/04/2015 15:04, Mike Miller a écrit :
> > On Tue, Apr 21, 2015 at 08:47:21 +0200, Julien Bect wrote:
> > > What does "native graphics" mean ?
> > The way I understand it is a blanket term to describe both the FLTK
> > and Qt plotting toolkits and the support libraries needed to make
> > those work.
>
> Ok... So, if "native graphics" covers both FLTK and Qt, considering the
> warnings :
>
> configure: WARNING: --without-fltk specified.  Native graphics will be
> disabled.
>
> configure: WARNING: I didn't find the necessary libraries to compile native
> configure: WARNING: graphics.  It isn't necessary to have native graphics,
> configure: WARNING: but you will need to have gnuplot installed or you
> won't
> configure: WARNING: be able to use any of Octave's plotting commands
>
> shouldn't I get gnuplot only ?

At one time, the only way to use OpenGL graphics was with FLTK widgets, 
so that combination was "native graphics".  That term was meant to say 
that plotting was done using a library directly linked with Octave, not 
using a separate external program (gnuplot).

> Let me try to explain (but please remember that I really don't
> understand much about this OpenGL / GLX / FTLK / Qt stuff...).

I don't either...

> I am building on a Debian Wheezzy system without direct rendering
> capabilities (no graphics card).
>
> I have, among other things, libgl1-mesa-glx, libgl1-mesa-dev and
> libqt4-opengl installed.
>
> When I configure with "--without-fltk", I still end up with both "qt"
> and "gnuplot" available as graphics toolkits.

That's what should happen.  The warning message is just bad.  Please 
feel free to suggest some better way of wording it.

> "qt" is selected as the default toolkit but I can't plot anything
> (figure successfully creates a frame, with various buttons and menus,
> but everything seems frozen and I can't plot).

So the libraries are present but you don't have the hardware to use 
them?  I don't know if that's actually the case, I'm just guessing.

> Does "native graphics" means the same as "direct rendering" ?
>
> Can I expect the Qt toolkit to work on a system without graphics card,
> using GLX ?

I think it should be possible, but maybe we aren't doing the right thing 
to make it work.

jwe