bugGNU Octave - Bugs: bug #39643, axes are not joined (onscreen)


bug #39643: axes are not joined (onscreen)

Submitted by:  Dmitri A. Sergatskov <dasergatskov>
Submitted on:  Thu 01 Aug 2013 12:49:02 PM UTC  
Category: Plotting with OpenGLSeverity: 3 - Normal
Priority: 5 - NormalItem Group: Other
Status: ConfirmedAssigned to: None
Originator Name: Dmitri A. SergatskovOpen/Closed: Open
Release: devOperating System: GNU/Linux

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Mon 28 Nov 2016 09:37:01 PM UTC, comment #9:

I pushed the patch here:


The remaining issue is rendering line cap and/or line join properly onscreen. The approach proposed in bug #46739 (polygon based dashed lines) is probably the way to go.

Pantxo Diribarne <pantxo>
Project Member
Mon 28 Nov 2016 05:16:19 PM UTC, comment #8:

Yes, test for gl2psLineJoin added in http://hg.savannah.gnu.org/hgweb/octave/rev/39f39eb4e476

Mike Miller <mtmiller>
Project Administrator
Mon 28 Nov 2016 04:44:33 PM UTC, comment #7:

No objection to pushing the cset that is available now.

I notice you make use of HAVE_GL2PSLINEJOIN. Who sets that variable? Is there a test in configure.ac for it?

Rik <rik5>
Project Administrator
Mon 28 Nov 2016 11:45:35 AM UTC, comment #6:

May I push the patch and leave this report open until we find a solution for onscreen rendering?

Pantxo Diribarne <pantxo>
Project Member
Tue 22 Nov 2016 03:41:28 PM UTC, comment #5:

I attached the resulting figure from ML 2015b

My understanding is that having the line join/cap right onscreen is only possible if we change our way to draw lines: instead of using GL_LINE objects we should draw lines using polygons.

In any event I think the change I propose is the right way to go for now even though it will only be effective once a new version of gl2ps is released and available.

(file #39046)

Pantxo Diribarne <pantxo>
Project Member
Sun 20 Nov 2016 08:29:39 PM UTC, comment #4:

I attached the png I obtain using Octave, the patch from comment #2 and the current dev version of gl2ps (see comment 27 in bug #48387).

(file #39033)

Pantxo Diribarne <pantxo>
Project Member
Sun 20 Nov 2016 06:20:17 PM UTC, comment #3:

For reference, here is some sample test code:

Could someone try the above code on Matlab and upload the resulting image?

Rik <rik5>
Project Administrator
Fri 18 Nov 2016 04:08:08 PM UTC, comment #2:

I was wondering if using LINE_STRIP to draw axes would do the trick for onscreen and printed figures, but LINE_STRIP which are used to draw line objects don't do a better job to join line segments (at least on my linux/nouveau driver):

I attached a patch that makes use of a new gl2psLineCap function in the current dev of gl2ps. This will thus only enhance the printout figure.

(file #39010)

Pantxo Diribarne <pantxo>
Project Member
Thu 01 Aug 2013 02:00:12 PM UTC, comment #1:

Drawing is done through OpenGL. FLTK-based drawing is not involved.

Michael Goffioul <goffioul>
Project Member
Thu 01 Aug 2013 12:49:02 PM UTC, original submission:

With fltk backend on Linux the axes lines are not joined in the corners. See attached for details; the axes width there set to 10 to make the problem more visible.

According to http://www.fltk.org/doc-1.3/drawing.html
If you don't specify a cap or join type you will get a system-defined default of whatever value is fastest.


so the bug might be OS (or even X11 server) dependent.

Dmitri A. Sergatskov <dasergatskov>


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

Attach File(s):

Attached Files
file #39046:  tst_linewidth.png added by pantxo (17KiB - image/png)
file #39033:  tst_join.png added by pantxo (12KiB - image/png)
file #39010:  linecap.patch added by pantxo (3KiB - text/x-diff)
file #28733:  axes.png added by dasergatskov (9KiB - image/png)


Depends on the following items: None found

   bug dependencies.


Carbon-Copy List
  • -unavailable- added by mtmiller (Posted a comment)
  • -unavailable- added by rik5 (Posted a comment)
  • -unavailable- added by pantxo (Updated the item)
  • -unavailable- added by goffioul (Posted a comment)
  • -unavailable- added by dasergatskov (Submitted the item)

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    Follow 8 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Tue 24 Apr 2018 12:18:17 AM UTCrik5Dependencies-=>bugs #53730 is dependent
    Thu 05 Oct 2017 06:14:31 PM UTCpantxoStatusPatch Submitted=>Confirmed
      Summaryaxes are not joined=>axes are not joined (onscreen)
    Tue 22 Nov 2016 03:41:28 PM UTCpantxoAttached File-=>Added tst_linewidth.png, #39046
    Sun 20 Nov 2016 08:29:39 PM UTCpantxoAttached File-=>Added tst_join.png, #39033
    Fri 18 Nov 2016 04:08:08 PM UTCpantxoAttached File-=>Added linecap.patch, #39010
      StatusNone=>Patch Submitted
    Thu 01 Aug 2013 12:49:02 PM UTCdasergatskovAttached File-=>Added axes.png, #28733

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