bugGNU Octave - Bugs: bug #57980, Transparent faces are not sorted...


bug #57980: Transparent faces are not sorted back to front

Submitted by:  None
Submitted on:  Tue 10 Mar 2020 12:42:31 AM UTC  
Category:  Plotting with OpenGL Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Feature Request
Status:  Confirmed Assigned to:  None
Originator Name:  Steve Shearer Originator Email:  -email is unavailable-
Open/Closed:  Open Release:  dev
Operating System:  Any

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Tue 10 Mar 2020 04:28:50 PM UTC, comment #1: 

Octave doesn't sort faces back to front which would be necessary for correct display.
See also the note in the documentation (scroll down to "facealpha"):

Marking as a feature request.

Markus M├╝tzel <mmuetzel>
Project Member
Tue 10 Mar 2020 12:42:31 AM UTC, original submission:  


I am a newbie, I hope I'm following proper procedure. I did look in the tracker to see if this issue has been reported - apparently it has not.

I am plotting a group of cubes, mainly on the z=0 plane, with the position representing time and frequency. I'd like for the cubes to be transparent, so I have set FaceAlpha = 0.2 or so.

The cubes are not really transparent when viewed from the front, but they become transparent when the graph is rotated around so one can view from the back.

I have attached a simple script with comments illustrating the issue.

Many thanks



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Attach Files:

Attached Files
file #48573:  transparency_bug.m added by None (1KiB - application/octet-stream - Script to illustrate the bug)


Depends on the following items: None found

Items that depend on this one: None found


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  • -email is unavailable- added by mmuetzel (Posted a comment)
  • -email is unavailable- added by None (Submitted the item)

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    Follow 6 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2020-03-10 mmuetzel Item GroupNone => Feature Request
        StatusNone => Confirmed
        Release5.1.0 => dev
        Operating SystemMicrosoft Windows => Any
        SummaryWhen plotting a cube it is only transparent when seen from the back => Transparent faces are not sorted back to front
    2020-03-10 None Attached File- => Added transparency_bug.m, #48573

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