Canvas popout windows
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Motivation
Some users have been wondering if it is possible that Canvas panels can be dragged to another monitor and or be resized if they are not modelled in a particular plane. [1]
one of the big problems of the FlightGear GUI is that it is "inside" the only and one main window. There is no possibility to have a separate window to not cover the main content, the scenery and the cockpit? This would make the GUI much more practical. [2]
It would be useful if the UI can be trivially hosted as an OpenGL overlay *or* a pop-out window, to give people the flexibility to move the UI to a second screen.[3]
Would it be possible to make the Canvas Windows leave the FlightGear borderspace? Like in P3D, I can right click a window and click “Undock Window”, which then gives it its own system title bar and then I can put it on other monitors.
If added, this could make 2D panels via Canvas a lot of useful! I can have the sim on one screen, and a radio stack on another, for example, to easily switch radios. Or a lighting panel.[4]
What I guess you want here, is to start creating the kind of GPS Ui that would be found in GA aircraft - for example a Garmin GNS 480 series or the more modern equivalent. This could be done as as a Nasal add-on so it could added as a variant into many GA aircraft including the C172, and would give you all the route-manager features and display.
(It could also be a pop-out Canvas window)[5]
Background
Currently, the GUI can only be placed inside one view/window (see Docs/README.multiscreen) but it would be nice to be able to move windows between views.[6]
Problem
It's possible to do, but it's definitely not trivial. There are two showstoppers:[7]
- Canvas uses nested cameras, not viewer-level slave cameras. You can only assign another GraphicsContext (another window) to slave cameras as nested cameras inherit their GraphicsContext from the main viewer camera. I think Tim Moore mentioned somewhere that he had a patch to move Canvas to slave cameras [8]
- CameraGroup hasn't been thought out from the beginning to support dynamic creation of windows. At startup the property tree in /sim/rendering/camera-group is read and the specified windows/cameras are created. I guess supporting this would require some architectural changes to CameraGroup.
Implementation
This can be solved by using multiple osg windows to contain whatever GUI solution we go with - canvas, osgWidget or PUI-port.[9] The current window manager registers itself to the main viewer and subscribes on osgGA events, so the canvas has no dependencies on the old system.[10]
See also
- Howto:CameraGroup talks
- http://www.openscenegraph.org/index.php/documentation/guides/programming-guides/93-viewer-vs-compositeviewer
- http://www.openscenegraph.org/index.php/documentation/knowledge-base/92-views-and-viewers
- https://sudonull.com/post/1525-OpenSceneGraph-Manage-Windows-and-Display-Modes