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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 ==
Line 439: Line 440:  
== Roadmap ==
 
== Roadmap ==
   −
=== Use CompositeViewer {{Pending}} ===
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=== Use CompositeViewer ===
{{See also|CompositeViewer Support}}
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{{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]].
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=== Standardize the View manager  ===
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{{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}} ===
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<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}} ===
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=== 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.
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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]] )
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* 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]]
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* [[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]
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* whether or not to enable OSG StatsHandler per view, i.e. for troubleshooting per view
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* 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
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* 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 ==

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