fltk does not work on cygwin version octave-6.4.0

[Takashi Yano]

On Tue, 21 Jun 2022 19:48:09 +0900 (JST)
Tatsuro MATSUOKA wrote:
> > From: "Takashi Yano" 
> > To: "cygwin>
> Cc: "Tatsuro MATSUOKA"
> > Date: 2022/06/21 火 18:45
> > Subject: Re: fltk does not work on cygwin version octave-6.4.0
>  
> > On Tue, 21 Jun 2022 14:15:12 +0900 (JST)
> > Tatsuro MATSUOKA wrote:
> > > fltk does not work on cygwin version octave-6.4.0
> > > 
> > > octave:1> graphics_toolkit fltk
> > > octave:2> plot(1:10);
> > > Insufficient GL support
> > > error: unable to plot due to insufficient OpenGL support
> > > 
> > > plot windows flashes and disappear immediately
> > 
> > I guess it depends on GPU. What GPU do you use?
> > It almost works in my environment except for that it needs
> > 'Reset Figure' to draw. Without 'Reset figure', the plot area
> > is filled gray. My GPU is GeForce GTX 750 Ti.
> > 
> My machine is very old.
> CPU Intel(R) Core(TM) i5 CPU       M 430  @ 2.27GHz   2.27 GHz
> GPU Intel(R) HD Graphics

I have tried on very similar machine:
CPU Intel(R) Core(TM) i5 CPU M 540 @ 2.53GHz
GPU Intel(R) HD Graphics

However, it works as expected, except that the following error message
appears.
libGL error: Windows-DRI extention disabled for GDI Generic renderer

$ env LIBGL_ALWAYS_SOFTWARE=1 octave
octave:1> graphics_toolkit fltk
octave:2> plot(1:10);

also works.

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>