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 OpenGL Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Other
Status:  Confirmed Assigned to:  None
Originator Name:  Dmitri A. Sergatskov Open/Closed:  Open
Release:  dev Operating System:  GNU/Linux

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( Jump to the original submission)

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.

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).

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

For reference, here is some sample test code:

close all;
hax = axes ('linewidth', 10, 'box', 'on');
print tst_join.png

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):

plot (rand (1,10), "linewidth", 10)

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>
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 Files:

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)


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    Follow 9 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2021-03-26 pantxo Dependencies- => bugs #60292 is dependent
    2018-04-24 rik5 Dependencies- => bugs #53730 is dependent
    2017-10-05 pantxo StatusPatch Submitted => Confirmed
        Summaryaxes are not joined => axes are not joined (onscreen)
    2016-11-22 pantxo Attached File- => Added tst_linewidth.png, #39046
    2016-11-20 pantxo Attached File- => Added tst_join.png, #39033
    2016-11-18 pantxo Attached File- => Added linecap.patch, #39010
        StatusNone => Patch Submitted
    2013-08-01 dasergatskov Attached File- => Added axes.png, #28733

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