Re: mxe-octave status

[John W. Eaton]

On 10/20/2017 04:28 PM, Philip Nienhuis wrote:

> Ah, I see I misunderstood; you mean that mesa version provokes a segfault.
> (Sorry for not following the whole issue in detail - which relates to 
> not having hit the issue with older system opengl32.dll libs yet.)

No, the mesa version works fine for me.  It's when I've built the qt5 
version with mesa and then I attempt to use the system opengl32.dll 
instead.  As far as I know, this should work since the API should be the 
same.  It's supposed to be a "drop-in replacement"

However, I haven't tried to build without the mesa opengl implementation 
and see whether that works.

> If I configure & build with --disable-system-opengl, install & then 
> remove opengl32.dll from the mxe-octave/bin/ subdir, would Octave fall 
> back to the system version in C:\Windows\system32 ?

Yes, if you restart Octave, it should dynamically link to whatever 
opengl32.dll is in the same directory with the .exe file or the first 
one found in the PATH.

And this DOES work for me when using qt4, so it seems most likely that 
the Qt5 widget doesn't work with my system opengl library, or that I'm 
using QOpenGLWidget incorrectly.

> or is the mxe-octave 
> version statically linked to graphics libraries?
> I'll just try it out this weekend.

No, it's not statically linked.  It's using the DLL (dynamic linking).

> (On this web page:
> http://doc.qt.io/qt-5/windows-requirements.html
> under "Dynamically Loading Graphics Drivers" I saw something about 
> dynamically loading opengl implementations. Would that be of any help 
> here?)

Possibly, but I don't think we need to do that.  Just choosing one 
implementation at startup should be sufficient.  We don't need to 
attempt to use multiple implementations simultaneously or swap between them.

jwe