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

[Dan Sebald]

Follow-up Comment #10, bug #52260 (project octave):

I'm attaching a diff file that adds a few lines to print out information to
stderr.  Here's what it looks like for me:


 h_axes3 = subplot (2, 2, 4);
  h_surf2 = surf (h_axes3, peaks, "LineStyle", "none");
  view (3);
  title ("Surface without lighting");

VW = 0 0 560 420
Mat1 = 1.000000 0.000000 0.000000 0.000000
Mat2 = 180.997043 0.000000 0.000000 0.000000


and I'm curious what is shown for your system (when in the mode that plots
axes upside down).  To apply, try something like

patch -p1 < dump_opengl_transform_info-djs2017oct23.diff

I guess what I'm most curious about is what VW looks like and whether yours
indicates 0 420 in the first two locations as opposed to 0 0.  The value back
from 


    glGetIntegerv (GL_VIEWPORT, vw);


is supposed to be the lower left corner.  A 0 420 would then mean that the
coordinate system has 0,0 at the top left.

Notice in this line of code:


    glOrtho (0, vw[2], vw[3], 0, xZ1, xZ2);


only vw[2] and vw[3] get used.  I don't see anywhere that vw[0] and vw[1] are
used.  Hence, I'm wondering if there is an inherent assumption in the Octave
code that the coordinate system is bottom left 0,0.

I can't explain why ticks and annotation come out correctly if the
orthographic projection is wrong.

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