bugGNU Octave - Bugs: bug #56979, Using plot3 parts of the curves...


bug #56979: Using plot3 parts of the curves are not visible

Submitter:  Albert <albertabc>
Submitted:  Tue 01 Oct 2019 04:08:57 PM UTC
Category:  Plotting with OpenGL Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Inaccurate Result
Status:  Confirmed Assigned to:  None
Originator Name:  Albert Open/Closed:  * Open
Release:  * dev Operating System:  * Any
Fixed Release:  None Planned Release:  None
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Wed 02 Oct 2019 07:53:04 PM UTC, comment #2: 

I can confirm the bug shown in comment #1. I think there are two issues:

  • z-fighting between grid lines and (1) plot lines or (2) axes main lines (y-axis in second image). The workaround is to either avoid using grids in 3D plots or manually change zlim so that grid and plot positions don't overlap (won't solve(2)), e.g:

ylim([0.95 2.05])

  • Even without any grid line or background axes plane, curves with high definition have spurious white pixels (onscreen and in raster printout). When the anti-aliasing is turned off, this effect disappears as noted in comment 9 of bug #54554. My guess is that the OpenGL rasterizer has hard time deciding what to do at line segment junctions.

Marking bug as OpenGL specific.

Pantxo Diribarne <pantxo>
Group Member
Tue 01 Oct 2019 04:27:20 PM UTC, comment #1: 


I tried your code and printed the figure using QT, FLTK and GnuPlot (see attached figures images)

It seems that only GnuPlot was NOT affected by the issue (see the red curve)

Leonardo <pocker>
Tue 01 Oct 2019 04:08:57 PM UTC, original submission:  

I have an issue using plot3.

I have plotted a sine curve i a 3d plot with a stepsize of 0.001 s and a length of 10 s.
Hugh parts of the curves are not visible.
With a stepsize of 0.1 s the hole curve is visible.
The effect depend on the stepsize of the data and the view angle.

A Octave script to reproduce the issue is appended to this ticket.

Albert <albertabc>


(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

Attach Files:

Attached Files
file #47609:  plot3_bug.PNG added by albertabc (53KiB - image/png - On my screen it looks liks this pikture. Which is quite different from yours.)
file #47605:  figure_fltk.png added by pocker (40KiB - image/png)
file #47606:  figure_qt.png added by pocker (56KiB - image/png)
file #47607:  figure_gnuplot.png added by pocker (39KiB - image/png)
file #47604:  Octave_3d_Bug.m added by albertabc (744B - application/octet-stream - Octave script to reproduce the error)


Depends on the following items: None found

Items that depend on this one: None found


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  • -email is unavailable- added by pantxo (Posted a comment)
  • -email is unavailable- added by pocker (Updated the item)
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  • -email is unavailable- added by albertabc

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    Follow 11 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2019-10-02 pantxo StatusNone Confirmed
    2019-10-02 pantxo CategoryPlotting Plotting with OpenGL
        Item GroupNone Inaccurate Result
        Release5.1.0 dev
        Operating SystemMicrosoft Windows Any
    2019-10-02 albertabc Attached File- Added plot3_bug.PNG, #47609
    2019-10-01 pocker Attached File- Added figure_fltk.png, #47605
        Attached File- Added figure_qt.png, #47606
        Attached File- Added figure_gnuplot.png, #47607
    2019-10-01 albertabc Attached File- Added Octave_3d_Bug.m, #47604
        Carbon-Copy- Added -email is unavailable-

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