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

 
 

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

Submitter:  None
Submitted:  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 Fixed Release:  None
Planned Release:  None
* Mandatory Fields

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Tue 03 Jan 2023 12:59:10 PM UTC, comment #6: 

Is there a mentor that would be willing and able to guide that student project?

Markus Mützel <mmuetzel>
Group administrator
Tue 03 Jan 2023 12:11:34 AM UTC, comment #5: 

https://wiki.octave.org/Summer_of_Code_-_Getting_Started#Suggested_projects

I added some draft text to the GSoC page about this project. Please review and edit as required.

Arun Giridhar <arungiridhar>
Group Member
Thu 29 Dec 2022 02:51:27 PM UTC, comment #4: 

Afaict, this would require major changes of the way we are rendering scenes for our figures. I wouldn't worry about this project being too small for a student project. It could rather be too complicated I'm afraid...
But for a capable, motivated student with some background in 3d rendering, this could well work out.

Markus Mützel <mmuetzel>
Group administrator
Thu 29 Dec 2022 02:45:40 PM UTC, comment #3: 

What would the scope of the project be?  Generally a single bugfix would be seen as insufficient, but if the work is a bit involved it could be. Alternatively if it is too small, it could be framed as part of a slightly bigger plotting/graphics rework project of there are similar things that could be grouped (without going to the other extreme and over-scoping of course)

Nicholas Jankowski <nrjank>
Group Member
Wed 28 Dec 2022 04:10:02 PM UTC, comment #2: 

It seems the back-to-front sorting feature would address several minor Matlab incompatibilities about graphics objects. Would it make a good GSoC project?

Arun Giridhar <arungiridhar>
Group Member
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"):
https://octave.org/doc/interpreter/Surface-Properties.html

Marking as a feature request.

Markus Mützel <mmuetzel>
Group administrator
Tue 10 Mar 2020 12:42:31 AM UTC, original submission:  

Hi,

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
Steve

Anonymous

 

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

 

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    Follow 8 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2022-02-24 mmuetzel Dependencies- bugs #62067 is dependent
    2020-09-18 mmuetzel Dependencies- bugs #59132 is dependent
    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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