bugGNU Octave - Bugs: bug #41294, FLTK does not draw linewidths...

 
 

bug #41294: FLTK does not draw linewidths >= 6 correctly

Submitter:  Rik <rik5>
Submitted:  Tue 21 Jan 2014 10:56:25 PM UTC
   
 
Category:  Plotting with OpenGL Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Incorrect Result
Status:  Invalid / Not an Octave Bug Assigned to:  None
Originator Name:  Open/Closed:  * Closed
Release:  * dev Operating System:  * GNU/Linux
Fixed Release:  None Planned Release:  None
* Mandatory Fields

Add a New Comment Rich Markup
   

Sun 20 Apr 2014 12:48:11 PM UTC, comment #4: 

One possible solution would be to render lines as quad when the linewidth is above a given value.

Michael Goffioul <goffioul>
Sun 20 Apr 2014 02:23:30 AM UTC, comment #3: 

I found the problem.  The issue is that OpenGL itself only supports a limited range of line widths.  It has a range both for aliased (jagged) and anti-aliased (smooth) lines.

I've attached code which will print out these ranges.  Unfortunately it's in C so you need to have the development packages for GL, GLU, and GLUT installed.  On Linux it compiles with


gcc -o rpt_lwidth rpt_lwidth.c -lGL -lGLU -lglut


In my case, the range of smooth lines is 1.0-5.0 and the granularity is 0.5 so I can really have lines from 0.5-5.5 which explains the issue.

I don't think there's much to be done about this so I'm closing the report.

(file #31215)

Rik <rik5>
Group administrator
Tue 18 Feb 2014 04:16:49 PM UTC, comment #2: 

Anti-aliasing neither helps nor hurts, but the lines are still not drawn correctly above 5.

Rik <rik5>
Group administrator
Sun 16 Feb 2014 09:30:57 PM UTC, comment #1: 
Felipe G. Nievinski <fgnievinski>
Tue 21 Jan 2014 10:56:25 PM UTC, original submission:  

Run the attached script mk_linewidths to generate a table of lines where the linewidth is equal to the y-value.  For linewidths greater than 5, Octave just draws a width=5 line.  See the attached pictures made with the FLTK and gnuplot toolkit.  gnuplot correctly keeps growing the line as the linewidth is increased.  Also, note that this is only an on-screen drawing issue.  Printing the plot to a file, which uses gl2ps, correctly scales the line.

Rik <rik5>
Group administrator

 

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

Attach Files:
   
   
Comment:
   

Attached Files
file #31215:  rpt_lwidth.c added by rik5 (907B - text/x-c)
file #30330:  mk_linewidths.m added by rik5 (169B - d2l/unknowntype)
file #30331:  gnuplot_linewidths.png added by rik5 (8KiB - image/png)
file #30332:  fltk_linewidths.png added by rik5 (12KiB - image/png)

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -email is unavailable- added by fgnievinski (Posted a comment)
  • -email is unavailable- added by rik5 (Submitted the item)
  •  

    There are 0 votes so far. Votes easily highlight which items people would like to see resolved in priority, independently of the priority of the item set by tracker managers.

    Only group members can vote.

     

    Follow 6 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2014-04-20 rik5 Attached File- Added rpt_lwidth.c, #31215
        StatusConfirmed Invalid / Not an Octave Bug
        Open/ClosedOpen Closed
    2014-01-21 rik5 Attached File- Added mk_linewidths.m, #30330
        Attached File- Added gnuplot_linewidths.png, #30331
        Attached File- Added fltk_linewidths.png, #30332

    Back to the top

    Powered by Savane 3.13-f8d8.
    Corresponding source code