Canvas view camera element: Difference between revisions

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Canvas view camera element (view source)

Revision as of 21:10, 26 November 2020

1,903 bytes added ,  26 November 2020
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* Missile/payload views
* Missile/payload views
* Prototyping/testing HUDs or PFDs requiring synthetic terrain to work properly
* Prototyping/testing HUDs or PFDs requiring synthetic terrain to work properly
* rendering an orthographic view to implement [[Canvas_Tile_Element|moving maps]] that render actual FlightGear terrain/DEM


== Proof of Concept ==
== Proof of Concept ==
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== Roadmap ==
== Roadmap ==


=== Use CompositeViewer {{Pending}} ===
=== Use CompositeViewer ===
{{See also|CompositeViewer Support}}
{{Progressbar|80}} {{See also|CompositeViewer Support}}  
<small>
Originally, FlightGear only used one instance of <tt>osg::Viewer</tt>, which is used by CameraGroup to manage the slave cameras. Supporting CompositeViewer did require modifying {{flightgear file|src/Viewer/fg_os_osgviewer.cxx}} to create some kind of wrapper class that manages the CompositeViewer instance and assign a CameraGroup to each <tt>osg::View</tt>. It's also important to note that currently all FG subsystems assume there is a single instance of [[Howto:CameraGroup talks|CameraGroup]].</small>


Currently FlightGear uses only one instance of <tt>osg::Viewer</tt>, which is used by CameraGroup to manage the slave cameras. Supporting CompositeViewer would require modifying {{flightgear file|src/Viewer/fg_os_osgviewer.cxx}} and creating some kind of wrapper class that manages the CompositeViewer instance and assigns a CameraGroup to each <tt>osg::View</tt>. It's also important to note that currently all FG subsystems assume there is a single instance of [[Howto:CameraGroup talks|CameraGroup]].
=== Standardize the View manager  ===
{{Note|As of 11/2020, Jules has already created a custom view manager implementation (Sview) that supports multiple independent instances, so this step might be obsolete by now.}}


=== Standardize the [[View manager]] {{Pending}} ===
<small>The first step would be to port the view code to SimGear so it can be used and known by the Compositor and Canvas. The view manager ({{flightgear file|src/Viewer/viewmgr.cxx}}) currently has some hardcoded assumptions, so it would either need to be rewritten to remove them or a new interface for the Views could be created specifically for the Canvas Camera View.
 
The first step would be to port the view code to SimGear so it can be used and known by the Compositor and Canvas. The view manager ({{flightgear file|src/Viewer/viewmgr.cxx}}) currently has some hardcoded assumptions, so it would either need to be rewritten to remove them or a new interface for the Views could be created specifically for the Canvas Camera View.


In FlightGear, the Canvas system (which resides in SimGear) is integrated using the equivalent of a FGCanvasSystemAdapter, which provides all FG APIs to SimGear and makes the Canvas system available inside FG: {{flightgear file|src/Canvas/FGCanvasSystemAdapter.cxx}}
In FlightGear, the Canvas system (which resides in SimGear) is integrated using the equivalent of a FGCanvasSystemAdapter, which provides all FG APIs to SimGear and makes the Canvas system available inside FG: {{flightgear file|src/Canvas/FGCanvasSystemAdapter.cxx}}


Instead of using tied properties, the adapted view code would either used propertyObject<> or the propertyBasedMgr abstraction, so that the corresponding canvas element can continue to use well-known conventions to manipulate views: ({{flightgear file|src/Viewer/view.cxx}})
Instead of using tied properties, the adapted view code would either used propertyObject<> or the propertyBasedMgr abstraction, so that the corresponding canvas element can continue to use well-known conventions to manipulate views: ({{flightgear file|src/Viewer/view.cxx}})
</small>


=== Create a Canvas Element subclass {{Pending}} ===
=== Create a Canvas Element subclass ===
{{Progressbar|30}}
{{See also|Talk:Hackathon Proposal: CompositeViewer and Canvas}}
{{See also|Talk:Hackathon Proposal: CompositeViewer and Canvas}}


This derived class would require the following configuration:
This derived class would require the following configuration:
* [[Compositor]] to use.
* [[Compositor]] to use.
* Scene graph to use. By default the main scene graph would be used, but an arbitrary XML file can be loaded to [[Howto:Extending Canvas to support rendering 3D models|render a custom model]]. A typical use-case would be instruments that need to [[Shuttle ADI ball|manipulate/render a 3D object]] (for which we have working code, too)
* [[View manager|View]] to use. This could be one of the "main" ones (i.e. the ones on the main property tree), or a locally-defined one that is only known to this Canvas Element (think FLIR).
* [[View manager|View]] to use. This could be one of the "main" ones (i.e. the ones on the main property tree), or a locally-defined one that is only known to this Canvas Element (think FLIR).
* Scene graph to use. By default the main scene graph would be used, but an arbitrary XML file can be loaded to [[Howto:Extending Canvas to support rendering 3D models|render a custom model]]. A typical use-case would be instruments that need to [[Shuttle ADI ball|manipulate/render a 3D object]] (for which we have working code, too)
* Several optimization/miscellaneous parameters like framerate cap, node masks, LOD etc. <ref>https://forum.flightgear.org/viewtopic.php?f=71&t=32845&p=318027&hilit=canvas+draw+masks#p318028</ref>


Simplifying a lot, this Canvas Element would be an aggregation of a Compositor instance, a View and a pointer to a <tt>osg::Group</tt> representing the scene graph to render. This setup could be replicated in {{flightgear file|src/Viewer/fg_os_osgviewer.cxx}}, with the difference of ignoring Canvas and using native windowing features from OSG.
Several optimization/miscellaneous parameters exposed in the form of properties per element, like:
* texture size/resolution (see Fernando's comments here: [[Talk:Hackathon_Proposal:_CompositeViewer_and_Canvas#SceneGraph_Cameras_vs._Prerender_Cams]] )
* OSG rendering mode (continuous vs. lazy/on demand): <code>setRunFrameScheme( osgViewer::ViewerBase::ON_DEMAND );</code> <ref>https://forum.flightgear.org/viewtopic.php?f=71&t=17650&hilit=knuq+taxiways&start=15#p166990</ref> <ref>https://stackoverflow.com/a/12259344</ref>
* framerate cap via something like <code>view.setRunMaxFrameRate()</code> [https://www.programmersought.com/article/23264806182/] [https://www.mail-archive.com/osg-users@openscenegraph.net/msg14033.html] (background: https://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg26178.html )
* [[Draw masks|node masks]]
* [[Level Of Detail (LOD) Ranges|LOD]] ranges etc. <ref>https://forum.flightgear.org/viewtopic.php?f=71&t=32845&p=318027&hilit=canvas+draw+masks#p318028</ref>
* PagedLOD settings for <code>PIXEL_SIZE_ON_SCREEN</code> mode [https://sourceforge.net/p/flightgear/mailman/message/36438416/] [http://alphapixel.com/wp-content/uploads/2015/04/LOD-Level-of-detail-in-OpenSceneGraph-OSG.pdf] [https://osg-users.openscenegraph.narkive.com/DNuWtUiR/pagedlods-and-pixel-to-screen-size]
* whether or not to enable OSG StatsHandler per view, i.e. for troubleshooting per view
* whether or not to enable event handling: "Extra view windows don't yet handle events so one cannot change the view angle/zoom after creation." <ref>https://sourceforge.net/p/flightgear/mailman/message/37161269/</ref>
 
Simplifying a lot, this Canvas Element would be an aggregation of:
* a Compositor instance / effect scheme
* a View  
* a pointer to a <tt>osg::Group</tt> representing the scene graph to render (e.g. alias or filename based).
 
This setup could be replicated in {{flightgear file|src/Viewer/fg_os_osgviewer.cxx}}, with the difference of ignoring Canvas and using native windowing features from OSG (see Jules' fgcommands to clone a view and open a dedicated GraphicsContext/window).


== Related ==
== Related ==
Retrieved from "https://wiki.flightgear.org/Special:MobileDiff/129047...129241"

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