[Octave-bug-tracker] [bug #55699] plot markers should not scale linearly as it causes deformations when size crossed odd/even pixel numbers

[Rik]

URL:
  <https://savannah.gnu.org/bugs/?55699>

                 Summary: plot markers should not scale linearly as it causes
deformations when size crossed odd/even pixel numbers
                 Project: GNU Octave
            Submitted by: rik5
            Submitted on: Mon 11 Feb 2019 02:33:17 PM PST
                Category: Plotting with OpenGL
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Inaccurate Result
                  Status: Confirmed
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: Any

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Details:

The function make_marker_list in gl-render.cc should be updated so that when
sizes (specified in points) result in an odd or even number of pixels for the
marker size, the result is still drawn correctly.

Here is a sample


clf;
set (gcf, 'graphicssmoothing', 'off');
hl = plot (1:10, ones (1,10), 'sb', 'linewidth', 3/4, 'markersize', 3);
hold on
hl2 = plot (1:10, ones (1,10), '.r', 'linewidth', 3/4, 'markersize', 3/4);


In the plot, the dot marker isn't drawn at positions 3 and 8.  And the square
marker doesn't particularly look like a square.

All markers need review.





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