PUI: Difference between revisions

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== Replacement status ==
== Replacement status ==
{{See also|FlightGear_and_OpenGL_ES#Example:_disabling_PUI}}


According to devel list comments in 10/2019, the new GUI has been incubating for a few years, but there's apparently been a lot of progress recently.
As of 03/2020, the PLIB replacement was reported to be in the backlog <ref>{{cite web
  |url    =  https://sourceforge.net/p/flightgear/mailman/message/36951255/
  |title  =  <nowiki>Re: [Flightgear-devel] C++ and/or OSG question </nowiki>
  |author =  <nowiki> Scott Giese </nowiki>
  |date  =  Mar 18th, 2020
  |added  =  Mar 18th, 2020
  |script_version = 0.50
  }}</ref>.
 
The new GUI has been incubating for a few years, but there's apparently been a lot of progress as of 10/2019.


It is likely the new GUI will be a user opt-in feature - at least initially. The sunset of the PLIB library _could_ happen relatively soon, but  
It is likely the new GUI will be a user opt-in feature - at least initially. The sunset of the PLIB library _could_ happen relatively soon, but  
people will need to see the new GUI and react to it before we could commit to PLIB removal.<ref>https://sourceforge.net/p/flightgear/mailman/message/36784489/</ref>
people will need to see the new GUI and react to it before we could commit to PLIB removal <ref>{{cite web
  |url    =  https://sourceforge.net/p/flightgear/mailman/message/36784489/  
  |title  =  <nowiki>Re: [Flightgear-devel] in Flightgear/Simgear C++ Code: What needs Doing? What are YOU Doing? What would you do if you had the time? </nowiki>
  |author =  <nowiki> Scott Giese </nowiki>
  |date  =  Oct 14th, 2020
  |added  =  Oct 14th, 2020
  |script_version = 0.50
  }}</ref>.


In 02/2019, James stated that the new UI is coming quite soon. <ref>{{cite web
  |url    =  https://sourceforge.net/p/flightgear/mailman/message/36589420/
  |title  =  <nowiki> Re: [Flightgear-devel] Lagging </nowiki>
  |author =  <nowiki> James Turner </nowiki>
  |date  =  Feb 17th, 2019
  |added  =  Feb 17th, 2019
  |script_version = 0.40
  }}</ref>
In 10/2017, James said he was getting really close to having the PUI replacement UI suitable for beta-testing.<ref>{{cite web
In 10/2017, James said he was getting really close to having the PUI replacement UI suitable for beta-testing.<ref>{{cite web
   |url    =  https://sourceforge.net/p/flightgear/mailman/message/36067646/  
   |url    =  https://sourceforge.net/p/flightgear/mailman/message/36067646/  
Line 70: Line 95:
   |date  =  Oct 8th, 2017  
   |date  =  Oct 8th, 2017  
   |added  =  Oct 8th, 2017  
   |added  =  Oct 8th, 2017  
  |script_version = 0.40
  }}</ref>
In 02/2019, James stated that the new UI is coming quite soon. <ref>{{cite web
  |url    =  https://sourceforge.net/p/flightgear/mailman/message/36589420/
  |title  =  <nowiki> Re: [Flightgear-devel] Lagging </nowiki>
  |author =  <nowiki> James Turner </nowiki>
  |date  =  Feb 17th, 2019
  |added  =  Feb 17th, 2019
   |script_version = 0.40  
   |script_version = 0.40  
   }}</ref>
   }}</ref>
Line 149: Line 165:
{{Appendix}}
{{Appendix}}


[[Category:PUI]]
[[Category:PUI| ]]

Revision as of 16:01, 5 April 2020

Caution  The feature documented below, in its current form, is currently being scheduled/expected (or discussed) to be significantly updated, or phased out, in future FlightGear versions + (rough estimate). This should be taken into account if you're interested in working on the feature or developing it further. If in doubt, please get in touch via the devel list first.

(PUI is likely to be removed to help improve compatibility with OSG/OpenGL 3.x and improve performance by phasing out legacy OpenGL code. Therefore, people should be careful when using/extending the PUI based legacy GUI engine[1][2] and coordinate any related work with the devel mailing list-this applies particularly to adding any additional hard-coded PUI widgets.)

FlightGear GUI dialog (exit.xml)stored in $FG_ROOT/gui/dialogs


Custom-autopilot-dialog.png

PUI is the standard GUI engine used in FlightGear, it is part of PLIB and is using raw, fixed-pipeline, OpenGL code internally (no OpenSceneGraph). PUI provides a fairly basic, but robust, set of widgets. PUI is also used for rendering the Menubar:

Menubar2.jpg

Replacement status

As of 03/2020, the PLIB replacement was reported to be in the backlog [3].

The new GUI has been incubating for a few years, but there's apparently been a lot of progress as of 10/2019.

It is likely the new GUI will be a user opt-in feature - at least initially. The sunset of the PLIB library _could_ happen relatively soon, but people will need to see the new GUI and react to it before we could commit to PLIB removal [4].

In 02/2019, James stated that the new UI is coming quite soon. [5] In 10/2017, James said he was getting really close to having the PUI replacement UI suitable for beta-testing.[6]


Originally, James was hoping to land the PUI replacement GUI in the last dev cycle in 2017 (at least as a proof-of-concept, probably not as the default UI), so wouldn’t expend lots of effort on things like collapsible sections which might be a lot of work with the current PUI/Canvas approaches, but are trivial with the new QtQuick based UI scheme.[7]


Once the basic new UI is in place we can experiment with different re-arrangements easily, without being limited by PUI. (James expects PUI to live on as the default / alternate UI while this happens)[8]

Technically, this entails replacing dialog.cxx with some code which builds up some special ‘PUI-Emulation’ QtQuick controls, so that existing dialogs (especially from Aircraft) continue to work. This mode will look somewhat ugly but hopefully no more ugly than PUI! And it helps that the set of widgets we have in PUI is limited, and the ‘tricky’ widgets (map, scrolling list, etc) are in the dialogs will will replace with new ones first.[9]

This PUI emulation isn't going to use any code from PLIB, so what will remain from it in FG afterwards will be the FNT and JS components (reworked).[10]

Background

In FlightGear, PUI dialogs are standard PropertyList XML Files that are stored in $FG_ROOT/gui/dialogs, they can contain the widgets mentioned in $FG_ROOT/Docs/README.gui, using a simple layout engine discussed in $FG_ROOT/Docs/README.layout, and bindings using a combination of so called fgcommands operating on properties (see $FG_ROOT/Docs/README.commands) and custom Nasal (FlightGear scripting) code.

In addition, each PUI/XML dialog may contain Nasal script sections that are executed when opening/closing the dialog, a feature which is commonly used for procedurally creating/updating widgets using the cmdarg() API, which allows the dialog tree to be traversed and manipulated prior to the dialog being rendered. Widgets can be conditionally hidden/shown using a wrapper for SGCondition in props.nas The canvas widget also supports its own embedded Nasal code section to execute arbitrary widget specific Nasal code upon opening/closing the dialog/widget.

PUI/XML dialogs can be loaded, dynamically created, updated and closed using a handful of fgcommands:

  • dialog-new
  • dialog-show
  • dialog-update
  • dialog-apply
  • dialog-close

PUI related OpenGL code is particularly infamous for causing rendering artifacts for people on AMD/ATI and Intel hardware (especially in combination with certain fonts/styles and effects/shaders).

PUI is also known to affect rendering performance quite significantly, while also preventing FlightGear from using a more recent version of OpenGL[11][12].

However, improving the frame-rate and modernised 3D rendering, can’t be worked on until the PUI code, 2D panels and Shiva are removed, but doing so is a frustrating slow path[13]

Besides, while most people seem to agree PUI needs to be replaced, it sounds as if the fallout from doing so would be more painful (cumulatively) than the pain its existence causes.[14]

But given that with many graphics drivers PUI doesn't render correctly when higher shader quality is on, graphics folks are also convinced it needs to be replaced.[15]


In addition, OpenSceneGraph (OSG) can obviously not help optimize any PUI related GL code and PUI widgets are generally considered to be pretty archaic and not easy to extend[16][17][18].

Note  We use the GUI code from PLIB, which doesn't know anything about OSG. See the SGPuDrawable class in $FG_SRC/Viewer/renderer.cxx for the implementation. The one catch is that OSG has a strong notion of separation between the update of a "scene" and its rendering, and that might not play well with arbitrary existing OpenGL code.

For these reasons, we're hoping to phase out PUI in FlightGear. One of the lowest hanging fruits is re-implementing the Menubar by using a Nasal/Canvas translator

Canvas-menubar-jabberwocky-09-2014.png


As of late 2015, there is heavy activity towards providing alternatives to a PUI-based UI:

References

References
  1. https://sourceforge.net/p/flightgear/mailman/message/34921495/
  2. Torsten Dreyer  (Jun 14th, 2016).  Re: [Flightgear-devel] GUI options (Was: Aircraft center) .
  3. Scott Giese  (Mar 18th, 2020). Re: [Flightgear-devel] C++ and/or OSG question .
  4. Scott Giese  (Oct 14th, 2020). Re: [Flightgear-devel] in Flightgear/Simgear C++ Code: What needs Doing? What are YOU Doing? What would you do if you had the time? .
  5. James Turner  (Feb 17th, 2019).  Re: [Flightgear-devel] Lagging .
  6. James Turner  (Oct 7th, 2017).  Re: [Flightgear-devel] PLIB features in plib svn but not in any release .
  7. James Turner  (Oct 1st, 2017).  Re: [Flightgear-devel] Canvas MapLayer for OpenStreetMap, OpenAIP, VFR Sectionals .
  8. James Turner  (Oct 2nd, 2017).  Re: [Flightgear-devel] FGFS macOS Menubar .
  9. James Turner  (Oct 8th, 2017).  Re: [Flightgear-devel] PLIB features in plib svn but not in any release .
  10. Florent Rougon  (Oct 8th, 2017).  Re: [Flightgear-devel] PLIB features in plib svn but not in any release .
  11. http://sourceforge.net/p/flightgear/mailman/message/34532040/
  12. http://forum.flightgear.org/viewtopic.php?f=71&t=24046
  13. James Turner  (Jan 24th, 2017).  Re: [Flightgear-devel] canvas non svg-elements broken .
  14. James Turner  (Jan 24th, 2017).  Re: [Flightgear-devel] canvas non svg-elements broken .
  15. Thorsten Renk  (Jan 25th, 2017).  Re: [Flightgear-devel] canvas non svg-elements broken .
  16. http://sourceforge.net/p/flightgear/mailman/message/26832164/
  17. http://sourceforge.net/p/flightgear/mailman/message/10587120/
  18. http://sourceforge.net/p/flightgear/mailman/message/10587272/