[Octave-bug-tracker] [bug #57464] patch plot of quadrilateral ill shaped

[Hg200]

URL:
  <https://savannah.gnu.org/bugs/?57464>

                 Summary: patch plot of quadrilateral ill shaped
                 Project: GNU Octave
            Submitted by: hg200
            Submitted on: Sun 22 Dec 2019 07:41:13 PM UTC
                Category: Plotting
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Matlab Compatibility
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: other
        Operating System: GNU/Linux

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Details:

The patch plot command can be used to plot polygons like quadrilaterals. The
four vertices may not be within a plane. In this case the quadrilateral is
split in order to show it correctly.

Sometimes the quadrilateral is displayed ill shaped (split angle too steep?).
picture1 shows the result of the attached script *test_patch.m* in octave as
well as matlab. The plot output differs.

The second picture (picture2) shows a streamribbon where this behaviour can
become an issue. One plot is made with patch () the other with surface (). It
looks like surface () shows quadrilaterals always correctly.

For streamribbon.m i will continue with surface () instead of patch ()
therefore marking as Matlab Compatibility.



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File Attachments:


-------------------------------------------------------
Date: Sun 22 Dec 2019 07:41:13 PM UTC  Name: picture1.png  Size: 32KiB   By:
hg200

<http://savannah.gnu.org/bugs/download.php?file_id=48100>
-------------------------------------------------------
Date: Sun 22 Dec 2019 07:41:13 PM UTC  Name: test_patch.m  Size: 490B   By:
hg200

<http://savannah.gnu.org/bugs/download.php?file_id=48101>
-------------------------------------------------------
Date: Sun 22 Dec 2019 07:41:13 PM UTC  Name: picture2.png  Size: 23KiB   By:
hg200

<http://savannah.gnu.org/bugs/download.php?file_id=48102>

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