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[Octave-bug-tracker] [bug #52260] Axes appear upside down with Qt5

From: Dan Sebald
Subject: [Octave-bug-tracker] [bug #52260] Axes appear upside down with Qt5
Date: Sun, 22 Oct 2017 02:55:56 -0400 (EDT)
User-agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:55.0) Gecko/20100101 Firefox/55.0

Follow-up Comment #5, bug #52260 (project octave):

Things look normal here with Qt toolkit.  

So, the tick marks and tick annotation appear in the proper location but the
lines for the axes and grid are reflected about the height dimension of the
window?  It sure looks that way.  The lines for the top subplots are hidden
behind the axes surfaces of the bottom subplots, but there are definitely some
snippets of the line still visible to indicate the axes lines are present.

Fascinating.  At first I was wondering how could this be possible.  But now
that I think about it, it's not so mystifying.  In imaging and window layout
it isn't uncommon for the "y" axis of the two dimensional window (not the
projection) to have 0,0 in the upper left corner as opposed to the typical
Cartesian coordinate system.  So, my guess is that's what is at play here. 
Either there is a bug in your driver that is assuming a default of 0,0 in the
upper-left corner when it shouldn't, or Octave isn't somehow initializing the
coordinate system and by chance all of our drivers assume 0,0 in the
lower-left corner.  But again, the tick marks and annotation are in the
correct spots--so it could be that not until far into the middle of the OpenGL
commands to create the plot that some action causes the coordinate system to
change to 0,0 in the lower-left corner.

Could you please do the following and report back what you see?  After
generating the Qt plot, there should be a "Rotate" button with a circular
arrow in the menu of the plot.  Click on there and then attempt to
mouse-press-then-drag and rotate the 3D plot.  Are the axes lines for that
plot corrected by that action?  Or do they still continue to draw upside down?
 You might try the other menu buttons such as "Axes" and "Grid".

You might have to spend some time delving into the active driver on your
system, hardware card, etc.  


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