Canvas view camera element: Difference between revisions

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{{Stub}}
{{FGCquote
  |It would make sense to integrate all efforts ([[CompositeViewer Support|CompositeViewer]], [[Canvas]] and [[Compositor]]) to create a [[Canvas_Development#Elements|Canvas Element]] that can render an [[Canvas_Development#Supporting_Cameras|arbitrary view]].
 
Some time ago I wrote what I think are the required steps to get something like cockpit mirrors working: [[#Roadmap]]
 
The main showstopper was having [[CompositeViewer Support]], but since that effort is underway, all the parts are there for someone willing to dive in.
  |{{cite web |url=https://sourceforge.net/p/flightgear/mailman/message/37089780/
    |title=<nowiki>Independent view windows</nowiki>
    |author=<nowiki>Fernando García Liñán </nowiki>
    |date=<nowiki>2020-08-20 14:27:58</nowiki>
  }}
}}


{{infobox subsystem
{{infobox subsystem
|image      = Canvas-view-element-prototype-by-icecode gl.png
|name        = Canvas Camera Views
|name        = Canvas Camera Views
|started    = 08/2016 (prototyped by F-JJTH)
|description = Rendering arbitrary views to a texture/Canvas
|description = adds support for rendering slave scenery views to a FBO/RTT (texture)
|status      = planned/prototype
|status      = experimental/known issues (being prepared for review/integration)
|maintainers = none
|maintainers = none
|developers  = F-JJTH, Icecode GL, Hooray
|developers  = none
}}
}}


== Background ==


Last updated in 09/2017
Several aircraft developers have manifested their interest in being able to render scene views to a texture (RTT) {{Wikipedia|Render target}} and use it inside cockpits as mirrors, external cameras (so called tail cams) and other uses.
 
== Summary ==


Several aircraft developers have manifested their interest in being able to render to a texture (RTT) {{Wikipedia|Render target}} and use it inside cockpits as mirrors, external cameras (so called tail cams) and other uses. Effects and shaders developers have also reached a point where ignoring RTT is a waste of resources and a limitating factor when creating new effects. Although this Canvas element is directed mainly towards the first need, it is a first step forward in terms of finally exposing Render To Texture capabilities to non-C++ space too.
With the [[Compositor]] framework it's possible to configure custom render pipelines in XML space, which together with Effect schemes allow complete control over how a rendered scene looks. A synthetic terrain can be rendered by assigning an Effect scheme to a <tt>scene</tt> type pass, which textures all terrain with a brown checkerboard pattern and paints the sky in a solid blue color. All other objects are ignored and aren't rendered, saving a lot of computation time. Custom render distances independent from the main LOD settings can also be used to further optimize the performance of the display.


== Use Cases ==
== Use Cases ==
* Tail Cams
* Tail Cams (gear view)
* Mirrors
* Mirrors
* In-sim view configuration
* Dynamic in-sim view configuration
* On demand creation of views and windows
* On demand creation of views and windows (e.g. [[FGCamera]] previews)
* 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


== Status ==
== Proof of Concept ==
{{See also|View manager}}
{{Note|This is inspired by the long standing idea to render camera views to a texture for use as tailcams, gear views etc <ref>https://forum.flightgear.org/viewtopic.php?f=71&t=23929</ref>, it's based on code originally provided by F-JJTH<ref>https://forum.flightgear.org/viewtopic.php?f=71&t=23929#p317448</ref>, and subsequently reworked by Icecode GL and Hooray to integrate it with the Canvas system back in 2017<ref>https://forum.flightgear.org/viewtopic.php?f=47&t=32846&p=318046</ref>
 
At the time, the main issue was that the new view element needed to be explicitly updated, but that should no longer be the case thanks to James' work on the setPixel() API <ref>https://sourceforge.net/p/flightgear/mailman/message/36926486/</ref> which also means that sc::Image now has a <code>dirtyPixels()</code> API which we can reuse <ref>https://sourceforge.net/p/flightgear/simgear/ci/ad3621e23b4056e1be7e8d9eb8dd4d513455add8/</ref>
We have a basic prototype, provided by F-JJTH, who developed the whole thing in mid-2016. There are a few issues, and it's using the legacy approach for implementing OD_gauge based avionics, i.e. not yet using the Canvas system.
Due to the adoption of the [[Compositor]] framework, this will probably need to reworked to be properly integrated.
 
Furthermore, beginning in mid 2020 Julian Smith has started working on optional [[CompositeViewer Support]] so that independent scene views can be rendered.  }}
We also have a quick, but working, integration in the form of a custom Canvas element provided by Icecode GL. Originally, the image was mirrored because of different coordinate systems. Apparently the missing piece was to use FG's view manager, which is now fixed, thanks to Clement's contribution.
 
Who knows, with cleaner code and some tweaks we could have a deferred renderer and RTT capabilities in Canvas space, as long as the effect framework can access these RTT contexts, as Hooray proposed multiple times.<ref>{{cite web
  |url    =  https://forum.flightgear.org/viewtopic.php?p=317743#p317743
  |title  = <nowiki> Re: Gear view in cockpit computer </nowiki>
  |author =  <nowiki> Icecode GL </nowiki>
  |date  =  Aug 28th, 2017
  |added  =  Aug 28th, 2017
  |script_version = 0.40
  }}</ref>
 
Also, Stuart offered to help review any patches and get them committed.  Please ping Stuart when you think the code is worth checking in. It doesn't have to be perfect - Particularly once the current release is out (2017.3). <ref>{{cite web
  |url    =  https://forum.flightgear.org/viewtopic.php?p=317967#p317967
  |title  =  <nowiki> Re: Gear view in cockpit computer </nowiki>
  |author =  <nowiki> stuart </nowiki>
  |date  =  Sep 1st, 2017
  |added  =  Sep 1st, 2017
  |script_version = 0.40
  }}</ref>
 
== The Future ==
for now we are emphasizing in implementing camera views in Canvas. We also keep in mind that this might be an important groundwork for what might be RTT support for effects/shaders. For that we obviously need a link between  Canvas and Effects. It's kind of a good thing that both systems are completely separated and don't know of each other, we are given more freedom when it comes to joining them. This link is kind of delicate and has to be well planned out.<ref>{{cite web
  |url    =  https://forum.flightgear.org/viewtopic.php?p=318059#p318059
  |title  =  <nowiki> Re: Canvas:View development </nowiki>
  |author =  <nowiki> Icecode GL </nowiki>
  |date  =  Sep 2nd, 2017
  |added  =  Sep 2nd, 2017
  |script_version = 0.40
  }}</ref>
 
Shaders can recieve many input textures and modern shaders support MRT (Multiple Render Targets) too. It makes sense to come up with some kind of well defined link between Canvas and Effects that allows for inputting/outputting canvases via effects. This would allow the same things that per-element effects would allow but with more flexibility and less overlapping functionality. <ref>{{cite web
  |url    =  https://forum.flightgear.org/viewtopic.php?p=318059#p318059
  |title  =  <nowiki> Re: Canvas:View development </nowiki>
  |author =  <nowiki> Icecode GL </nowiki>
  |date  =  Sep 2nd, 2017
  |added  =  Sep 2nd, 2017  
  |script_version = 0.40
  }}</ref>
 
it would be possible to also come up with an XML-configurable rendering pipeline - in fact, Zan once came up with a modified CameraGroup design that would move the whole hard-coded pipeline to XML space: [[Canvas Development#Supporting Cameras]]<ref>{{cite web
  |url    =  https://forum.flightgear.org/viewtopic.php?p=275228#p275228
  |title  = <nowiki> Re: Review of FG on reddit: xpost </nowiki>
  |author = <nowiki> Hooray </nowiki>
  |date  =  Feb 6th, 2016
  |added  =  Feb 6th, 2016
  |script_version = 0.40
  }}</ref>
 
Ideally, something like this would be integrated with the existing view manager, i.e. using the same property names (via property objects), and then hooked up to CanvasImage, e.g. as a custom '''camera://''' protocol (we already support canvas:// and http(s)://)
So some kind of dedicated CanvasCamera element would make sense, possibly inheriting from CanvasImage.
 
And it would also make sense to look at Zan's new-cameras patches, because those add tons of features to CameraGroup.cxx
This would already allow arbitrary views slaved to the main view (camera)
 
<ref>{{cite web
  |url    =  https://forum.flightgear.org/viewtopic.php?p=261665#p261665
  |title  =  <nowiki> Re: WINDOW IN WINDOW </nowiki>
  |author =  <nowiki> Hooray </nowiki>
  |date  =  Oct 25th, 2015
  |added  =  Oct 25th, 2015
  |script_version = 0.40
  }}</ref>
 
As has been said previously, the proper way to support "cameras" via Canvas is using CompositeViewer, which does require a re-architecting of several parts of FG: [[CompositeViewer Support]]
Given the current state of things, that seems at least another 3-4 release cycles away.
So, short of that, the only thing that we can currently support with reasonable effort is "slaved views" (as per $FG_ROOT/Docs/README.multiscreen).
That would not require too much in terms of coding, because the code is already there - in fact, CameraGroup.cxx already contains a RTT/FBO (render-to-texture) implementation that renders slaved views to an offscreen context. This is also how Rembrandt buffers are set up behind the scenes.
So basically, the code is there, it would need to be extracted/genralied and turned into a CanvasElement, and possibly integrated with the existing view manager code.
And then, there also is Zan's newcameras branch, which exposes rendering stages (passes) to XML/property tree space, so that individual stages are made accessible to shaders/effects.
Thus, most of the code is there, it is mainly a matter of integrating things, i.e. that would require someone able to build SG/FG from source, familiar with C++ and willing/able to work through some OSG tutorials/docs to make this work<ref>{{cite web
  |url    =  https://forum.flightgear.org/viewtopic.php?p=260810#p260810
  |title  =  <nowiki> Re: WINDOW IN WINDOW </nowiki>
  |author =  <nowiki> Hooray </nowiki>
  |date  =  Oct 17th, 2015
  |added  =  Oct 17th, 2015
  |script_version = 0.40
  }}</ref>
 
Canvas is/was primarily about exposing 2D rendering to fgdata space, so that fgdata developers could incorporatedevelop and maintain 2D rendering related features without having to be core developers (core development being an obvious bottleneck, as well as having  significant barrier to entry).
In other words, people would need to be convinced that they want to let Canvas evolve beyond the 2D use-case, i.e. by allowing effects/shaders per element, but also to let Cameras be created/controlled easily.
Personally, I do believe that this is a worthwhile thing to aim for, as it would help unify (and simplify) most RTT/FBO handling in SG/FG, and make this available to people like Thorsten who have a track record of doing really fancy, unprecedented stuff, with this flexibility.
Equally, there are tons of use-cases where aircraft/scenery developers may want to set up custom cameras (A380 tail cam, space shuttle) and render those to an offscreen texture (e.g. GUI dialog and/or MFD screen).
It is true that "slaved views" are kinda limited at the moment, but they are also comparatively easy to set up, so I think that supporting slaved camera views via Canvas could be a good way to bootstrap/boost this development and pave the way for CompositeViewer adoption/integration in the future. <ref>{{cite web
  |url    =  https://forum.flightgear.org/viewtopic.php?p=260810#p260810
  |title  =  <nowiki> Re: WINDOW IN WINDOW </nowiki>
  |author =  <nowiki> Hooray </nowiki>
  |date  =  Oct 17th, 2015
  |added  =  Oct 17th, 2015
  |script_version = 0.40
  }}</ref>
 
== Gallery ==
 
{|style="margin: 0 auto;"
| [[File:Early-canvas-view-screenshot.png|thumb|Screenshot showing early experiments rendering a model to a Canvas view]]
| [[File:Icecode GL-Canvas-Camera-support.png|thumb|upright|An experimental [[Canvas]] element to render slaved scenery views to a custom Canvas texture, to be used for creating custom tail-cams/mirror textures and so on]]
| [[File:Icecodes slave cams 09-2017.png|thumb|upright|Several Canvas dialogs with view manager views]]
| [[File:Canvas-view-element-prototype-by-icecode gl.png|thumb|upright|[[Canvas]] gui dialog with a custom canvas element to display view manager views (based on code prototyped by F-JJTH)]]
|}
 
== Implementation details / for the reviewer ==
 
{{Note|This section provides a rough overview for the potentiaal reviewer, which is also intended to be used as the commit message when/if this should get committed}}
 
This set of patches (touching SimGear and fgdata) implements a new <code>Canvas::Element</code> by creating a sub-class named <code>Canvas::View</code>. The meat of it is in the constructor, i.e. <code>Canvas::View::View()</code>, where an off-screen camera (RTT/FBO) is set up, the FGCanvasSystemAdapter file has been extended to provide access to the FlightGear view manager to compute/obtain the view-specific view matrix, which is then used by the view element to update the offscreen camera in Canvas::View::update() accordingly.
 
This is also a good way to stress-test the renderer, as new cameras can be easily added to the scene at runtime, so that the impact of doing so can be easily measured.
 
To actually test the new element using the [[Nasal Console]] and paste the following snippet of code into it:
 
<syntaxhighlight lang="nasal">
var (width,height) = (512,512);
var ELEMENT_NAME = "viewcam";
 
var display_view = func(view=0) {
var title = 'Canvas test:' ~ ELEMENT_NAME;
var window = canvas.Window.new([width,height],"dialog").set('title',title);
var myCanvas = window.createCanvas().set("background", canvas.style.getColor("bg_color"));
var root = myCanvas.createGroup();
 
var child = root.createChild( ELEMENT_NAME );
# child.set("view-number", view);
} # display_view()
 
 
var totalViews = props.getNode("sim").getChildren("view");
forindex(var v;totalViews) {
display_view(view: v);
}</syntaxhighlight>
 
Aircraft developers can use the new Canvas '''view''' element simply by using the conventional approach to replace a static texture with a Canvas using a cockpit placement.
 
== Roadmap ==
{{PatchAvailable|url=https://forum.flightgear.org/viewtopic.php?f=71&t=23929#p317448}}
 
 
* extend FGCanvasSystemAdapter to make the view manager available there <ref>https://forum.flightgear.org/viewtopic.php?f=71&t=23929&p=317798#p317798</ref>
* come up with a new Canvas element inheriting from Canvas::Image {{Progressbar|80}}
* add Clement's camera setup routines
* make the camera render into the texture used by the sub-class
* this should be named viewmgr-camera or something like that to make it obvious what it is doing
 
== Testing ==
Once we have a basic prototype working, the new camera element needs to be tested, specifically:
* using different resolutions (resizing at runtime?)
* displaying multiple/independent camera views
* all supported Canvas placements
* shaders and effects
* ALS
* Rembrandt
* Reset/re-init
* OSG threading modes
 
== Known Issues ==
* texture/view matrix updates don't currently take effect unless .update() is specifically invoked
* <del>skydome handling (probably missing effect/shader or wrong root node)</del> {{Done}} (by Icecode_GL)
* change DATA_VARIANCE for texture setup, analogous to the Canvas::Image::Image ctor
* make the size of the texture re-configurable using properties
 
== Troubleshooting ==
* update the texture specific osg::StateSet to force an update of the texture
* compare the scenegraph generated for sc::View vs. sc::Image using http://wiki.flightgear.org/Canvas_Troubleshooting#Dumping_Canvas_scene_graphs_to_disk
* check whether sub-classing sc::Image and  directly using its _texture makes any difference or not
** if it does, we could just as well add support for a custom <code>view://by-number/</code> protocol to the src/filename handling helper
* if all else fails, use an osg::Image and assign it to the texture and invoke its dirty() method to update the whole thing
 
== Ideas ==
{{See also|Canvas_Troubleshooting#Adding_draw_masks_for_Canvas}}
* do we need support for looking up view numbers by name ?
* support draw-masks for scene graph features (terrain, skydome, models etc): " it'd be benefitial in the long run to let the user choose what part of the scene graph they want to show. This would be useful for deferred rendering schemes, where sometimes you don't need to display the whole scenery to save some precious frames. Canvas makes that easy with all of its property handling"
* work out what is needed for [https://forum.flightgear.org/viewtopic.php?f=71&t=27985&p=264718&hilit=synthetic+terrain#p264718v synthetic terrain views] [http://www.aircraftspruce.eu/catalog/graphics/10-03932s.jpg]
* support effects/shaders: This is fairly straightforward to do, just create a EffectsGeode, fill it with a "compiled" .eff, and substitute the standard osg::Geode for it. But I don't think that's going to give us the flexibility we need. A shader won't be able to access several canvases at the same time if we do things that way.
* introduce some sort of STL cache using something like std::map<std::string, osg::Texture2D> to only ever update/draw a view once, no matter how often it is shown by different elements/placements ?
 
== Performance / Optimizations ==
{{See also|Canvas_Troubleshooting#Hooking_up_Canvas_and_Osg_Stats}}
* Configurable refresh rate per view. 15 fps might be enough for a external camera, we don't need to draw at max rate.<ref>{{cite web
  |url    =  https://forum.flightgear.org/viewtopic.php?p=318028#p318028
  |title  =  <nowiki> Re: Canvas::View element: performance/optimizations </nowiki>
  |author =  <nowiki> Icecode GL </nowiki>
  |date  =  Sep 2nd, 2017
  |added  =  Sep 2nd, 2017
  |script_version = 0.40
  }}</ref>
* provide a view-cache using a STL std::map<> ?
* use PBOs [http://forum.openscenegraph.org/viewtopic.php?t=10713&view=next]
* consider hooking up the whole thing to the FGStatsManager (OSG stats) ?
* Torsten implemented some [[PagedLOD]] scheme to only render AI entities/objects if they're actually visible in terms of pixels on the screen <ref>{{cite web
  |url    =  https://sourceforge.net/p/flightgear/mailman/message/33057570/
  |title  =  <nowiki> [Flightgear-devel] Improved LOD handling for AI Models </nowiki>
  |author =  <nowiki> Torsten Dreyer </nowiki>
  |date  =  Nov 19th, 2014
  |added  =  Nov 19th, 2014
  |script_version = 0.40
  }}</ref> <ref>{{cite web
  |url    =  https://sourceforge.net/p/flightgear/mailman/message/33271362/
  |title  =  <nowiki> Re: [Flightgear-devel] Flightgear next (3.5.0) Does not render MP
  aircraft </nowiki>
  |author =  <nowiki> Torsten Dreyer </nowiki>
  |date  =  Jan 26th, 2015
  |added  =  Jan 26th, 2015
  |script_version = 0.40
  }}</ref>
 
== C++ ==
The following is the boilerplate code neede to add a new element to the Canvas system inheriting from the Canvas::Image class, i.e. an element having its own allocated Image/texture buffer, which is what we can use to render a camera into it:


SimGear:
<syntaxhighlight lang="diff">
<syntaxhighlight lang="diff">
 
diff --git a/simgear/canvas/CanvasSystemAdapter.hxx b/simgear/canvas/CanvasSystemAdapter.hxx
index 43b3f780..0fb62170 100644
--- a/simgear/canvas/CanvasSystemAdapter.hxx
+++ b/simgear/canvas/CanvasSystemAdapter.hxx
@@ -35,11 +35,13 @@ namespace canvas
      virtual ~SystemAdapter() {}
      virtual FontPtr getFont(const std::string& name) const = 0;
-      virtual void addCamera(osg::Camera* camera) const = 0;
+      virtual void addCamera(osg::Camera* camera, bool useSceneData = false) const = 0;
      virtual void removeCamera(osg::Camera* camera) const = 0;
      virtual osg::ref_ptr<osg::Image> getImage(const std::string& path) const = 0;
+      virtual osg::Node* getModel(const std::string& path) const = 0;
      virtual SGSubsystem* getSubsystem(const std::string& name) const = 0;
      virtual HTTP::Client* getHTTPClient() const = 0;
+      virtual osg::Matrix getViewMatrix(int view_number, double dt) const = 0;
  };
} // namespace canvas
diff --git a/simgear/canvas/canvas_fwd.hxx b/simgear/canvas/canvas_fwd.hxx
index 3b1b4646..97e9bd64 100644
--- a/simgear/canvas/canvas_fwd.hxx
+++ b/simgear/canvas/canvas_fwd.hxx
@@ -24,6 +24,7 @@
#include <osg/ref_ptr>
#include <osgText/Font>
+#include <osg/Node>
#include <boost/function.hpp>
#include <boost/shared_ptr.hpp>
diff --git a/simgear/canvas/elements/CMakeLists.txt b/simgear/canvas/elements/CMakeLists.txt
diff --git a/simgear/canvas/elements/CMakeLists.txt b/simgear/canvas/elements/CMakeLists.txt
index 2b537c0..4eb1e95 100644
index 2b537c0c..4eb1e955 100644
--- a/simgear/canvas/elements/CMakeLists.txt
--- a/simgear/canvas/elements/CMakeLists.txt
+++ b/simgear/canvas/elements/CMakeLists.txt
+++ b/simgear/canvas/elements/CMakeLists.txt
Line 267: Line 101:
+)
+)
diff --git a/simgear/canvas/elements/CanvasGroup.cxx b/simgear/canvas/elements/CanvasGroup.cxx
diff --git a/simgear/canvas/elements/CanvasGroup.cxx b/simgear/canvas/elements/CanvasGroup.cxx
index c753c2e..5d2585e 100644
index c753c2e2..6cec072f 100644
--- a/simgear/canvas/elements/CanvasGroup.cxx
--- a/simgear/canvas/elements/CanvasGroup.cxx
+++ b/simgear/canvas/elements/CanvasGroup.cxx
+++ b/simgear/canvas/elements/CanvasGroup.cxx
@@ -23,6 +23,8 @@
@@ -23,6 +23,7 @@
  #include "CanvasMap.hxx"
  #include "CanvasMap.hxx"
  #include "CanvasPath.hxx"
  #include "CanvasPath.hxx"
  #include "CanvasText.hxx"
  #include "CanvasText.hxx"
+#include "CanvasView.hxx"
+#include "CanvasView.hxx"
+
  #include <simgear/canvas/CanvasEventVisitor.hxx>
  #include <simgear/canvas/CanvasEventVisitor.hxx>
  #include <simgear/canvas/events/MouseEvent.hxx>
  #include <simgear/canvas/events/MouseEvent.hxx>
   
   
@@ -66,6 +68,7 @@ namespace canvas
@@ -66,6 +67,7 @@ namespace canvas
     add<Map  >(_child_factories);
     add<Map  >(_child_factories);
     add<Path >(_child_factories);
     add<Path >(_child_factories);
Line 289: Line 122:
diff --git a/simgear/canvas/elements/CanvasView.cxx b/simgear/canvas/elements/CanvasView.cxx
diff --git a/simgear/canvas/elements/CanvasView.cxx b/simgear/canvas/elements/CanvasView.cxx
new file mode 100644
new file mode 100644
index 0000000..edae7ab
index 00000000..502e82d7
--- /dev/null
--- /dev/null
+++ b/simgear/canvas/elements/CanvasView.cxx
+++ b/simgear/canvas/elements/CanvasView.cxx
@@ -0,0 +1,88 @@
@@ -0,0 +1,91 @@
+// This library is free software; you can redistribute it and/or
+#include <simgear/canvas/Canvas.hxx>
+// modify it under the terms of the GNU Library General Public
+#include <simgear/canvas/CanvasMgr.hxx>
+// License as published by the Free Software Foundation; either
+#include <simgear/canvas/CanvasSystemAdapter.hxx>
+// version 2 of the License, or (at your option) any later version.
+
+//
+#include <simgear/scene/util/OsgMath.hxx>
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// Library General Public License for more details.
+//
+// You should have received a copy of the GNU Library General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
+
+
+#include <simgear_config.h>
+#include "CanvasView.hxx"
+#include "CanvasView.hxx"
+
+
+#include <cmath>
+#include <iostream>
+
+#include <osg/io_utils>
+#include <boost/algorithm/string/predicate.hpp>
+
+
+namespace simgear
+namespace simgear
Line 319: Line 142:
+{
+{
+
+
+ //----------------------------------------------------------------------------
+const std::string View::TYPE_NAME = "view";
const std::string View::TYPE_NAME = "view-camera";
+
+
+ //----------------------------------------------------------------------------
+void View::staticInit()
void View::staticInit()
+{
+ {
+    if ( isInit<View>() )
+    Image::staticInit();
+        return;
+}
+
+View::View( const CanvasWeakPtr& canvas,
+              const SGPropertyNode_ptr& node,
+              const Style& parent_style,
+              ElementWeakPtr parent ) :
+    Element(canvas, node, parent_style, parent),
+    _width(512),
+    _height(512)
+{
+    staticInit();
+
+    _texture = new osg::Texture2D;
+    _texture->setDataVariance(osg::Object::DYNAMIC);
+    _texture->setTextureSize(_width, _height);
+    _texture->setInternalFormat(GL_RGBA);
+    _texture->setFilter(osg::Texture2D::MIN_FILTER, osg::Texture2D::LINEAR);
+    _texture->setFilter(osg::Texture2D::MAG_FILTER, osg::Texture2D::LINEAR);
+
+
+    if( isInit<View>() )
+    _camera = new osg::Camera;
+     return;
+    _camera->setDataVariance(osg::Object::DYNAMIC);
+    _camera->setViewport(0, 0, _width, _height);
+    _camera->setClearColor(osg::Vec4(1.0f, 1.0f, 1.0f, 1.0f));
+    _camera->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+   _camera->setRenderOrder(osg::Camera::PRE_RENDER);
+    _camera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT, osg::Camera::FRAME_BUFFER);
+    _camera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
+    double aspect_ratio = (double)_width / _height;
+    _camera->setProjectionMatrixAsPerspective(85.0, aspect_ratio, 0.1, 120000.0);
+
+
+    // Do some initialization if needed...
+    _camera->attach(osg::Camera::COLOR_BUFFER, _texture.get());
+  }
+
+
+ //----------------------------------------------------------------------------
+   if (Canvas::getSystemAdapter())
+  View::View( const CanvasWeakPtr& canvas,
+       Canvas::getSystemAdapter()->addCamera(_camera.get(), true);
+           const SGPropertyNode_ptr& node,
+            const Style& parent_style,
+            ElementWeakPtr parent ):
+    Image(canvas, node, parent_style, parent)
+  {
+    staticInit();
+  }
+
+
+ //----------------------------------------------------------------------------
+   _quad = osg::createTexturedQuadGeometry(osg::Vec3(0.0,    0.0,    0.0),
+ View::~View()
+                                            osg::Vec3(_width, 0.0,    0.0),
+ {
+                                           osg::Vec3(0.0,    _height, 0.0),
+                                           // In Canvas (0,0) is the top left corner, while in OSG/OpenGL
+                                            // it's the bottom left corner.
+                                            0.0, 1.0, 1.0, 0.0);
+    _quad->getOrCreateStateSet()->setTextureAttributeAndModes(0, _texture.get(), osg::StateAttribute::ON);
+
+
+ }
+   setDrawable(_quad.get());
+}
+
+
+ //----------------------------------------------------------------------------
+View::~View()
+  void View::update(double dt)
+{
+ {
+    if( _camera.valid() && Canvas::getSystemAdapter() )
+    Image::update(dt);
+        Canvas::getSystemAdapter()->removeCamera(_camera.get());
+ }
+    _camera.release();
+    _texture.release();
+}
+
+
+ //----------------------------------------------------------------------------
+void View::update(double dt)
void View::childAdded(SGPropertyNode* parent, SGPropertyNode* child)
+{
+ {
+   osg::Matrix view_matrix = Canvas::getSystemAdapter()->getViewMatrix(0, dt);
+     return Image::childAdded(parent, child);
+   _camera->setViewMatrix(view_matrix);
+ }
+
+
+ //----------------------------------------------------------------------------
+   Element::update(dt);
+  void View::childRemoved(SGPropertyNode* parent, SGPropertyNode* child)
+}
+  {
+      return Image::childRemoved(parent, child);
+ }
+
+
+ //----------------------------------------------------------------------------
+void View::resize(int width, int height)
void View::valueChanged(SGPropertyNode* child)
+{
+ {
+    return Image::valueChanged(child);
+  }
+
+
+ //----------------------------------------------------------------------------
+}
+  void View::childChanged(SGPropertyNode* child)
+  {
+      return Image::childChanged(child);
+
+
+  }
+} // namespace canvas
+} // namespace canvas
+} // namespace simgear
+} // namespace simgear
diff --git a/simgear/canvas/elements/CanvasView.hxx b/simgear/canvas/elements/CanvasView.hxx
diff --git a/simgear/canvas/elements/CanvasView.hxx b/simgear/canvas/elements/CanvasView.hxx
new file mode 100644
new file mode 100644
index 0000000..7b2ec4e
index 00000000..8cb3cc49
--- /dev/null
--- /dev/null
+++ b/simgear/canvas/elements/CanvasView.hxx
+++ b/simgear/canvas/elements/CanvasView.hxx
@@ -0,0 +1,59 @@
@@ -0,0 +1,39 @@
+// Based on https://forum.flightgear.org/viewtopic.php?f=71&t=23929
+//
+// This library is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Library General Public
+// License as published by the Free Software Foundation; either
+// version 2 of the License, or (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Library General Public License for more details.
+//
+// You should have received a copy of the GNU Library General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
+
+#ifndef CANVAS_VIEW_HXX_
+#ifndef CANVAS_VIEW_HXX_
+#define CANVAS_VIEW_HXX_
+#define CANVAS_VIEW_HXX_
+
+
+#include "CanvasImage.hxx"
+#include "CanvasElement.hxx"
+
+#include <boost/shared_ptr.hpp>
+#include <boost/unordered_map.hpp>
+#include <boost/unordered_set.hpp>
+
+
+namespace simgear
+namespace simgear
Line 416: Line 232:
+namespace canvas
+namespace canvas
+{
+{
+  class View:
+    public Image
+  {
+    public:
+      static const std::string TYPE_NAME;
+      static void staticInit();
+
+
+     View( const CanvasWeakPtr& canvas,
+class View : public Element {
+public:
+    static const std::string TYPE_NAME;
+    static void staticInit();
+
+    View( const CanvasWeakPtr& canvas,
+          const SGPropertyNode_ptr& node,
+          const SGPropertyNode_ptr& node,
+          const Style& parent_style,
+          const Style& parent_style = Style(),
+          ElementWeakPtr parent = 0 );
+          ElementWeakPtr parent = 0 );
+     virtual ~View();
+   virtual ~View();
+
+    virtual void update(double dt);
+
+
+     virtual void update(double dt);
+   virtual void resize(int width, int height);
+
+
+     virtual void childAdded( SGPropertyNode * parent,
+protected:
+                              SGPropertyNode * child );
+      virtual void childRemoved( SGPropertyNode * parent,
+                                SGPropertyNode * child );
+      virtual void valueChanged(SGPropertyNode * child);
+
+
+    //protected:
+    osg::ref_ptr<osg::Camera> _camera;
+    osg::ref_ptr<osg::Texture2D> _texture;
+
+
+     virtual void childChanged(SGPropertyNode * child);
+   osg::ref_ptr<osg::Geometry> _quad;
+ };
+
+    int _width, _height;
+};
+
+
+} // namespace canvas
+} // namespace canvas
+} // namespace simgear
+} // namespace simgear
+
+
+#endif /* CANVAS_VIEW_HXX_ */
+#endif // CANVAS_VIEW_HXX_
</syntaxhighlight>
 
FlightGear
<syntaxhighlight lang="diff">   
diff --git a/src/Canvas/FGCanvasSystemAdapter.cxx b/src/Canvas/FGCanvasSystemAdapter.cxx
index 72b20747e..9e04dbd14 100644
--- a/src/Canvas/FGCanvasSystemAdapter.cxx
+++ b/src/Canvas/FGCanvasSystemAdapter.cxx
@@ -23,9 +23,18 @@
#include <Network/HTTPClient.hxx>
#include <Viewer/renderer.hxx>
 
+
+#include <Viewer/view.hxx>
+#include <Viewer/viewmgr.hxx>
+#include <simgear/scene/util/OsgMath.hxx>
+
+
+
#include <osgDB/ReadFile>
#include <stdexcept>
 
+#include <simgear/scene/model/modellib.hxx>
+
namespace canvas
{
//----------------------------------------------------------------------------
@@ -64,9 +73,9 @@ namespace canvas
}
 
//----------------------------------------------------------------------------
-  void FGCanvasSystemAdapter::addCamera(osg::Camera* camera) const
+  void FGCanvasSystemAdapter::addCamera(osg::Camera* camera, bool useSceneData) const
{
-    globals->get_renderer()->addCamera(camera, false);
+    globals->get_renderer()->addCamera(camera, useSceneData);
}
 
//----------------------------------------------------------------------------
@@ -100,6 +109,46 @@ namespace canvas
return 0;
}
 
+    //----------------------------------------------------------------------------
+    // From http://wiki.flightgear.org/Howto:Extending_Canvas_to_support_rendering_3D_models#Extending_FGCanvasSystemAdapter
+    osg::Node* FGCanvasSystemAdapter::getModel(const std::string& path) const
+    {
+        const char *model_path = "Models/Geometry/glider.ac";
+        SGPath p(SGPath::fromUtf8(path));
+
+        if( p.isAbsolute() )
+        {
+            SGPath valid_path = fgValidatePath(p, false);
+            if( !valid_path.isNull() )
+            try {
+                std::string fullPath = simgear::SGModelLib::findDataFile(valid_path.local8BitStr());
+                osg::Node * object = simgear::SGModelLib::loadDeferredModel(fullPath, globals->get_props());
+                return object;
+            } catch (const sg_throwable& t) {
+                SG_LOG(SG_IO, SG_ALERT, "Error loading " << model_path << ":\n  " << t.getFormattedMessage() << t.getOrigin());
+                return 0;
+            } // error loading from absolute path
+            SG_LOG(SG_IO, SG_ALERT, "canvas::Model: reading '" << path << "' denied");
+        } // absolute path handling
+        else
+        {
+            SGPath tpath = globals->resolve_resource_path(path);
+            if( !tpath.isNull() )
+            try {
+                std::string fullPath = simgear::SGModelLib::findDataFile(path.c_str());
+                osg::Node * object = simgear::SGModelLib::loadDeferredModel(fullPath, globals->get_props());
+                return object;
+            } catch (const sg_throwable& t) {
+                SG_LOG(SG_IO, SG_ALERT, "Error loading " << model_path << ":\n  " << t.getFormattedMessage() << t.getOrigin());
+                return 0;
+            } // error loading from relative path
+
+            SG_LOG(SG_IO, SG_ALERT, "canvas::Model: No such model: '" << path << "'");
+        } // relative path handling
+
+        return 0;
+    }
+
//----------------------------------------------------------------------------
SGSubsystem*
FGCanvasSystemAdapter::getSubsystem(const std::string& name) const
@@ -121,4 +170,16 @@ namespace canvas
return 0;
}
 
+  osg::Matrix FGCanvasSystemAdapter::getViewMatrix(int view_number, double dt) const
+  {
+        flightgear::View *view = globals->get_viewmgr()->get_view(view_number);
+        view->update(dt);
+
+        osg::Vec3f position( toOsg(view->getViewPosition()) );
+        osg::Quat orientation( toOsg(view->getViewOrientation()) );
+        osg::Matrix viewMatrix( osg::Matrix::translate(-position) * osg::Matrix::rotate(orientation.inverse()) );
+
+        return viewMatrix;
+  }
+
}
diff --git a/src/Canvas/FGCanvasSystemAdapter.hxx b/src/Canvas/FGCanvasSystemAdapter.hxx
index 4c1fd6210..24ececb41 100644
--- a/src/Canvas/FGCanvasSystemAdapter.hxx
+++ b/src/Canvas/FGCanvasSystemAdapter.hxx
@@ -28,11 +28,13 @@ namespace canvas
{
public:
virtual simgear::canvas::FontPtr getFont(const std::string& name) const;
-      virtual void addCamera(osg::Camera* camera) const;
+      virtual void addCamera(osg::Camera* camera, bool useSceneData = false) const;
virtual void removeCamera(osg::Camera* camera) const;
virtual osg::ref_ptr<osg::Image> getImage(const std::string& path) const;
+      virtual osg::Node* getModel(const std::string& path) const;
virtual SGSubsystem* getSubsystem(const std::string& name) const;
virtual simgear::HTTP::Client* getHTTPClient() const;
+      virtual osg::Matrix getViewMatrix(int view_number, double dt) const;
};
}
 
diff --git a/src/Viewer/renderer.cxx b/src/Viewer/renderer.cxx
index d9e8f351f..b9b3fc6a0 100644
--- a/src/Viewer/renderer.cxx
+++ b/src/Viewer/renderer.cxx
@@ -1845,6 +1845,8 @@ FGRenderer::setEventHandler(FGEventHandler* eventHandler_)
void
FGRenderer::addCamera(osg::Camera* camera, bool useSceneData)
{
+    if (useSceneData)
+        camera->addChild(globals->get_scenery()->get_scene_graph());
_viewerSceneRoot->addChild(camera);
}




</syntaxhighlight>
</syntaxhighlight>


== Base Package ==
fgdata
{{collapsible script
<syntaxhighlight lang="diff">
| type  = view-camera
| title  = view-camera  $FG_ROOT/Nasal/canvas/api.nas changes
| intro = Finally, we need to modify api.nas to provide Nasal wrappers
| script =  
diff --git a/Nasal/canvas/api.nas b/Nasal/canvas/api.nas
diff --git a/Nasal/canvas/api.nas b/Nasal/canvas/api.nas
index 6d39d03..f98fdd9 100644
index 3f7f5a17..433a41f9 100644
--- a/Nasal/canvas/api.nas
--- a/Nasal/canvas/api.nas
+++ b/Nasal/canvas/api.nas
+++ b/Nasal/canvas/api.nas
@@ -1099,13 +1099,21 @@ var Image = {
@@ -1132,10 +1132,10 @@ var Image = {
   }
   }
  };
  };
   
   
+var viewCamera = {
-var Model = {
new: func(ghost)
+var View = {
{
  new: func(ghost)
+    return {parents: [viewCamera, Element.new(ghost)]};
  {
},
-    return {parents: [Model, Element.new(ghost)]};
+};
+    return {parents: [View, Element.new(ghost)]};
+
  },
  # Element factories used by #Group elements to create children
};
Group._element_factories = {
   
  "group": Group.new,
@@ -1146,7 +1146,7 @@ Group._element_factories = {
  "map": Map.new,
   "text": Text.new,
   "text": Text.new,
   "path": Path.new,
   "path": Path.new,
"image": Image.new
  "image": Image.new,
+ "image": Image.new,
- "model": Model.new
+  "view-camera": viewCamera.new,
+  "view": View.new
  };
  };
| lang = diff
}}
# Canvas
</syntaxhighlight>
 
== Roadmap ==


== Nasal Console ==
=== Use CompositeViewer {{Pending}} ===
{{See also|CompositeViewer Support}}


After patching and rebuilding SimGear/FlightGear respectively, and applying the changes to to api.nas in the base package, the following can be pasted into the [[Nasal Console]] for testing purposes:
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]].


<syntaxhighlight lang="nasal">
=== Standardize the [[View manager]] {{Pending}} ===
# TODO: this must match the TYPE_NAME used by the C++ code
var ELEMENT_NAME ="view-camera"; # to be adapted according to the C++ changes


var myElementTest = {
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.
##
# constructor
new: func( camera ) {
  var m = { parents: [myElementTest] };
  m.dlg = canvas.Window.new([camera.width,camera.height],"dialog");
  m.canvas = m.dlg.createCanvas().setColorBackground(1,1,1,1);
  m.root = m.canvas.createGroup();


  ##
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}}
  # instantiate a new element
  m.myElement = m.root.createChild( ELEMENT_NAME );
  # set the view-number property
  m.myElement.set("view-number", camera.view);
  m.dlg.set("title", "view #"~camera.view); # TODO look up proper title/name


  return m;
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}})
}, # new
}; # end of myElementTest


# TODO: get list of all views ?
=== Create a Canvas Element subclass {{Pending}} ===
{{Main article|Canvas_Development#Adding_a_new_Element}}


var cameras = [
This derived class would require the following configuration:
{view: 0, width : 640, height: 480},
* [[Compositor]] to use.
{view: 1, width : 320, height: 160},
* [[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: 2, width : 320, height: 160},
* 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, etc.


foreach(var cam; cameras) {
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.
var newCam = myElementTest.new( cam );
}
</syntaxhighlight>


== Related ==
== Related ==
{{Appendix}}
 
=== Forum topics ===
* {{forum link|t=32846|text=Canvas::View Development}}
* {{forum link|t=23929|text=Gear View in Cockpit}}
* {{forum link|t=20057|text=Rear-View mirror}}
* {{forum link|t=18905|text=Progress on synthetic terrain}}
* {{forum link|t=17184|text=Instruments with heightmaps}}
 
[[Category:Canvas Element Proposals]]

Revision as of 17:49, 23 August 2020

Cquote1.png It would make sense to integrate all efforts (CompositeViewer, Canvas and Compositor) to create a Canvas Element that can render an arbitrary view.

Some time ago I wrote what I think are the required steps to get something like cockpit mirrors working: #Roadmap

The main showstopper was having CompositeViewer Support, but since that effort is underway, all the parts are there for someone willing to dive in.


— Fernando García Liñán  (2020-08-20 14:27:58). Independent view windows.
(powered by Instant-Cquotes)
Cquote2.png
Canvas Camera Views
Description Rendering arbitrary views to a texture/Canvas
Maintainer(s) none
Contributor(s) none
Status planned/prototype

Background

Several aircraft developers have manifested their interest in being able to render scene views to a texture (RTT) Render target This is a link to a Wikipedia article and use it inside cockpits as mirrors, external cameras (so called tail cams) and other uses.

With the Compositor framework it's possible to configure custom render pipelines in XML space, which together with Effect schemes allow complete control over how a rendered scene looks. A synthetic terrain can be rendered by assigning an Effect scheme to a scene type pass, which textures all terrain with a brown checkerboard pattern and paints the sky in a solid blue color. All other objects are ignored and aren't rendered, saving a lot of computation time. Custom render distances independent from the main LOD settings can also be used to further optimize the performance of the display.

Use Cases

  • Tail Cams (gear view)
  • Mirrors
  • Dynamic in-sim view configuration
  • On demand creation of views and windows (e.g. FGCamera previews)
  • Missile/payload views
  • Prototyping/testing HUDs or PFDs requiring synthetic terrain to work properly

Proof of Concept

Note  This is inspired by the long standing idea to render camera views to a texture for use as tailcams, gear views etc [1], it's based on code originally provided by F-JJTH[2], and subsequently reworked by Icecode GL and Hooray to integrate it with the Canvas system back in 2017[3]

At the time, the main issue was that the new view element needed to be explicitly updated, but that should no longer be the case thanks to James' work on the setPixel() API [4] which also means that sc::Image now has a dirtyPixels() API which we can reuse [5] Due to the adoption of the Compositor framework, this will probably need to reworked to be properly integrated. Furthermore, beginning in mid 2020 Julian Smith has started working on optional CompositeViewer Support so that independent scene views can be rendered.

SimGear:

diff --git a/simgear/canvas/CanvasSystemAdapter.hxx b/simgear/canvas/CanvasSystemAdapter.hxx
index 43b3f780..0fb62170 100644
--- a/simgear/canvas/CanvasSystemAdapter.hxx
+++ b/simgear/canvas/CanvasSystemAdapter.hxx
@@ -35,11 +35,13 @@ namespace canvas
 
       virtual ~SystemAdapter() {}
       virtual FontPtr getFont(const std::string& name) const = 0;
-      virtual void addCamera(osg::Camera* camera) const = 0;
+      virtual void addCamera(osg::Camera* camera, bool useSceneData = false) const = 0;
       virtual void removeCamera(osg::Camera* camera) const = 0;
       virtual osg::ref_ptr<osg::Image> getImage(const std::string& path) const = 0;
+      virtual osg::Node* getModel(const std::string& path) const = 0;
       virtual SGSubsystem* getSubsystem(const std::string& name) const = 0;
       virtual HTTP::Client* getHTTPClient() const = 0;
+      virtual osg::Matrix getViewMatrix(int view_number, double dt) const = 0;
   };
 
 } // namespace canvas
diff --git a/simgear/canvas/canvas_fwd.hxx b/simgear/canvas/canvas_fwd.hxx
index 3b1b4646..97e9bd64 100644
--- a/simgear/canvas/canvas_fwd.hxx
+++ b/simgear/canvas/canvas_fwd.hxx
@@ -24,6 +24,7 @@
 
 #include <osg/ref_ptr>
 #include <osgText/Font>
+#include <osg/Node>
 
 #include <boost/function.hpp>
 #include <boost/shared_ptr.hpp>
diff --git a/simgear/canvas/elements/CMakeLists.txt b/simgear/canvas/elements/CMakeLists.txt
index 2b537c0c..4eb1e955 100644
--- a/simgear/canvas/elements/CMakeLists.txt
+++ b/simgear/canvas/elements/CMakeLists.txt
@@ -7,6 +7,7 @@ set(HEADERS
   CanvasMap.hxx
   CanvasPath.hxx
   CanvasText.hxx
+  CanvasView.hxx
 )
 
 set(DETAIL_HEADERS
@@ -20,6 +21,7 @@ set(SOURCES
   CanvasMap.cxx
   CanvasPath.cxx
   CanvasText.cxx
+  CanvasView.cxx
 )
 
 simgear_scene_component(canvas-elements canvas/elements "${SOURCES}" "${HEADERS}")
@@ -28,4 +30,4 @@ simgear_component(canvas-elements/detail canvas/elements/detail "" "${DETAIL_HEA
 add_boost_test(canvas_element
   SOURCES canvas_element_test.cpp
   LIBRARIES ${TEST_LIBS}
-)
\ No newline at end of file
+)
diff --git a/simgear/canvas/elements/CanvasGroup.cxx b/simgear/canvas/elements/CanvasGroup.cxx
index c753c2e2..6cec072f 100644
--- a/simgear/canvas/elements/CanvasGroup.cxx
+++ b/simgear/canvas/elements/CanvasGroup.cxx
@@ -23,6 +23,7 @@
 #include "CanvasMap.hxx"
 #include "CanvasPath.hxx"
 #include "CanvasText.hxx"
+#include "CanvasView.hxx"
 #include <simgear/canvas/CanvasEventVisitor.hxx>
 #include <simgear/canvas/events/MouseEvent.hxx>
 
@@ -66,6 +67,7 @@ namespace canvas
     add<Map  >(_child_factories);
     add<Path >(_child_factories);
     add<Text >(_child_factories);
+    add<View >(_child_factories);
   }
 
   //----------------------------------------------------------------------------
diff --git a/simgear/canvas/elements/CanvasView.cxx b/simgear/canvas/elements/CanvasView.cxx
new file mode 100644
index 00000000..502e82d7
--- /dev/null
+++ b/simgear/canvas/elements/CanvasView.cxx
@@ -0,0 +1,91 @@
+#include <simgear/canvas/Canvas.hxx>
+#include <simgear/canvas/CanvasMgr.hxx>
+#include <simgear/canvas/CanvasSystemAdapter.hxx>
+
+#include <simgear/scene/util/OsgMath.hxx>
+
+#include "CanvasView.hxx"
+
+#include <iostream>
+#include <osg/io_utils>
+
+namespace simgear
+{
+namespace canvas
+{
+
+const std::string View::TYPE_NAME = "view";
+
+void View::staticInit()
+{
+    if ( isInit<View>() )
+        return;
+}
+
+View::View( const CanvasWeakPtr& canvas,
+              const SGPropertyNode_ptr& node,
+              const Style& parent_style,
+              ElementWeakPtr parent ) :
+    Element(canvas, node, parent_style, parent),
+    _width(512),
+    _height(512)
+{
+    staticInit();
+
+    _texture = new osg::Texture2D;
+    _texture->setDataVariance(osg::Object::DYNAMIC);
+    _texture->setTextureSize(_width, _height);
+    _texture->setInternalFormat(GL_RGBA);
+    _texture->setFilter(osg::Texture2D::MIN_FILTER, osg::Texture2D::LINEAR);
+    _texture->setFilter(osg::Texture2D::MAG_FILTER, osg::Texture2D::LINEAR);
+
+    _camera = new osg::Camera;
+    _camera->setDataVariance(osg::Object::DYNAMIC);
+    _camera->setViewport(0, 0, _width, _height);
+    _camera->setClearColor(osg::Vec4(1.0f, 1.0f, 1.0f, 1.0f));
+    _camera->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+    _camera->setRenderOrder(osg::Camera::PRE_RENDER);
+    _camera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT, osg::Camera::FRAME_BUFFER);
+    _camera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
+    double aspect_ratio = (double)_width / _height;
+    _camera->setProjectionMatrixAsPerspective(85.0, aspect_ratio, 0.1, 120000.0);
+
+    _camera->attach(osg::Camera::COLOR_BUFFER, _texture.get());
+
+    if (Canvas::getSystemAdapter())
+        Canvas::getSystemAdapter()->addCamera(_camera.get(), true);
+
+    _quad = osg::createTexturedQuadGeometry(osg::Vec3(0.0,    0.0,     0.0),
+                                            osg::Vec3(_width, 0.0,     0.0),
+                                            osg::Vec3(0.0,    _height, 0.0),
+                                            // In Canvas (0,0) is the top left corner, while in OSG/OpenGL
+                                            // it's the bottom left corner.
+                                            0.0, 1.0, 1.0, 0.0);
+    _quad->getOrCreateStateSet()->setTextureAttributeAndModes(0, _texture.get(), osg::StateAttribute::ON);
+
+    setDrawable(_quad.get());
+}
+
+View::~View()
+{
+    if( _camera.valid() && Canvas::getSystemAdapter() )
+        Canvas::getSystemAdapter()->removeCamera(_camera.get());
+    _camera.release();
+    _texture.release();
+}
+
+void View::update(double dt)
+{
+    osg::Matrix view_matrix = Canvas::getSystemAdapter()->getViewMatrix(0, dt);
+    _camera->setViewMatrix(view_matrix);
+
+    Element::update(dt);
+}
+
+void View::resize(int width, int height)
+{
+
+}
+
+} // namespace canvas
+} // namespace simgear
diff --git a/simgear/canvas/elements/CanvasView.hxx b/simgear/canvas/elements/CanvasView.hxx
new file mode 100644
index 00000000..8cb3cc49
--- /dev/null
+++ b/simgear/canvas/elements/CanvasView.hxx
@@ -0,0 +1,39 @@
+#ifndef CANVAS_VIEW_HXX_
+#define CANVAS_VIEW_HXX_
+
+#include "CanvasElement.hxx"
+
+namespace simgear
+{
+namespace canvas
+{
+
+class View : public Element {
+public:
+    static const std::string TYPE_NAME;
+    static void staticInit();
+
+    View( const CanvasWeakPtr& canvas,
+           const SGPropertyNode_ptr& node,
+           const Style& parent_style = Style(),
+           ElementWeakPtr parent = 0 );
+    virtual ~View();
+
+    virtual void update(double dt);
+
+    virtual void resize(int width, int height);
+
+protected:
+
+    osg::ref_ptr<osg::Camera> _camera;
+    osg::ref_ptr<osg::Texture2D> _texture;
+
+    osg::ref_ptr<osg::Geometry> _quad;
+
+    int _width, _height;
+};
+
+} // namespace canvas
+} // namespace simgear
+
+#endif // CANVAS_VIEW_HXX_

FlightGear

    
diff --git a/src/Canvas/FGCanvasSystemAdapter.cxx b/src/Canvas/FGCanvasSystemAdapter.cxx
index 72b20747e..9e04dbd14 100644
--- a/src/Canvas/FGCanvasSystemAdapter.cxx
+++ b/src/Canvas/FGCanvasSystemAdapter.cxx
@@ -23,9 +23,18 @@
#include <Network/HTTPClient.hxx>
#include <Viewer/renderer.hxx>

+
+#include <Viewer/view.hxx>
+#include <Viewer/viewmgr.hxx>
+#include <simgear/scene/util/OsgMath.hxx>
+
+
+
#include <osgDB/ReadFile>
#include <stdexcept>

+#include <simgear/scene/model/modellib.hxx>
+
namespace canvas
{
//----------------------------------------------------------------------------
@@ -64,9 +73,9 @@ namespace canvas
}

//----------------------------------------------------------------------------
-  void FGCanvasSystemAdapter::addCamera(osg::Camera* camera) const
+  void FGCanvasSystemAdapter::addCamera(osg::Camera* camera, bool useSceneData) const
{
-    globals->get_renderer()->addCamera(camera, false);
+    globals->get_renderer()->addCamera(camera, useSceneData);
}

//----------------------------------------------------------------------------
@@ -100,6 +109,46 @@ namespace canvas
return 0;
}

+    //----------------------------------------------------------------------------
+    // From http://wiki.flightgear.org/Howto:Extending_Canvas_to_support_rendering_3D_models#Extending_FGCanvasSystemAdapter
+    osg::Node* FGCanvasSystemAdapter::getModel(const std::string& path) const
+    {
+        const char *model_path = "Models/Geometry/glider.ac";
+        SGPath p(SGPath::fromUtf8(path));
+
+        if( p.isAbsolute() )
+        {
+            SGPath valid_path = fgValidatePath(p, false);
+            if( !valid_path.isNull() )
+            try {
+                std::string fullPath = simgear::SGModelLib::findDataFile(valid_path.local8BitStr());
+                osg::Node * object = simgear::SGModelLib::loadDeferredModel(fullPath, globals->get_props());
+                return object;
+            } catch (const sg_throwable& t) {
+                SG_LOG(SG_IO, SG_ALERT, "Error loading " << model_path << ":\n  " << t.getFormattedMessage() << t.getOrigin());
+                return 0;
+            } // error loading from absolute path
+            SG_LOG(SG_IO, SG_ALERT, "canvas::Model: reading '" << path << "' denied");
+        } // absolute path handling
+        else
+        {
+            SGPath tpath = globals->resolve_resource_path(path);
+            if( !tpath.isNull() )
+            try {
+                std::string fullPath = simgear::SGModelLib::findDataFile(path.c_str());
+                osg::Node * object = simgear::SGModelLib::loadDeferredModel(fullPath, globals->get_props());
+                return object;
+            } catch (const sg_throwable& t) {
+                SG_LOG(SG_IO, SG_ALERT, "Error loading " << model_path << ":\n  " << t.getFormattedMessage() << t.getOrigin());
+                return 0;
+            } // error loading from relative path
+
+            SG_LOG(SG_IO, SG_ALERT, "canvas::Model: No such model: '" << path << "'");
+        } // relative path handling
+
+        return 0;
+    }
+
//----------------------------------------------------------------------------
SGSubsystem*
FGCanvasSystemAdapter::getSubsystem(const std::string& name) const
@@ -121,4 +170,16 @@ namespace canvas
return 0;
}

+  osg::Matrix FGCanvasSystemAdapter::getViewMatrix(int view_number, double dt) const
+  {
+        flightgear::View *view = globals->get_viewmgr()->get_view(view_number);
+        view->update(dt);
+
+        osg::Vec3f position( toOsg(view->getViewPosition()) );
+        osg::Quat orientation( toOsg(view->getViewOrientation()) );
+        osg::Matrix viewMatrix( osg::Matrix::translate(-position) * osg::Matrix::rotate(orientation.inverse()) );
+
+        return viewMatrix;
+  }
+
}
diff --git a/src/Canvas/FGCanvasSystemAdapter.hxx b/src/Canvas/FGCanvasSystemAdapter.hxx
index 4c1fd6210..24ececb41 100644
--- a/src/Canvas/FGCanvasSystemAdapter.hxx
+++ b/src/Canvas/FGCanvasSystemAdapter.hxx
@@ -28,11 +28,13 @@ namespace canvas
{
public:
virtual simgear::canvas::FontPtr getFont(const std::string& name) const;
-      virtual void addCamera(osg::Camera* camera) const;
+      virtual void addCamera(osg::Camera* camera, bool useSceneData = false) const;
virtual void removeCamera(osg::Camera* camera) const;
virtual osg::ref_ptr<osg::Image> getImage(const std::string& path) const;
+      virtual osg::Node* getModel(const std::string& path) const;
virtual SGSubsystem* getSubsystem(const std::string& name) const;
virtual simgear::HTTP::Client* getHTTPClient() const;
+      virtual osg::Matrix getViewMatrix(int view_number, double dt) const;
};
}

diff --git a/src/Viewer/renderer.cxx b/src/Viewer/renderer.cxx
index d9e8f351f..b9b3fc6a0 100644
--- a/src/Viewer/renderer.cxx
+++ b/src/Viewer/renderer.cxx
@@ -1845,6 +1845,8 @@ FGRenderer::setEventHandler(FGEventHandler* eventHandler_)
void
FGRenderer::addCamera(osg::Camera* camera, bool useSceneData)
{
+    if (useSceneData)
+        camera->addChild(globals->get_scenery()->get_scene_graph());
_viewerSceneRoot->addChild(camera);
}

fgdata

diff --git a/Nasal/canvas/api.nas b/Nasal/canvas/api.nas
index 3f7f5a17..433a41f9 100644
--- a/Nasal/canvas/api.nas
+++ b/Nasal/canvas/api.nas
@@ -1132,10 +1132,10 @@ var Image = {
   }
 };
 
-var Model = {
+var View = {
   new: func(ghost)
   {
-    return {parents: [Model, Element.new(ghost)]};
+    return {parents: [View, Element.new(ghost)]};
   },
 };
 
@@ -1146,7 +1146,7 @@ Group._element_factories = {
   "text": Text.new,
   "path": Path.new,
   "image": Image.new,
-  "model": Model.new
+  "view": View.new
 };
 
 # Canvas

Roadmap

Use CompositeViewer Pending Pending

Currently FlightGear uses only one instance of osg::Viewer, which is used by CameraGroup to manage the slave cameras. Supporting CompositeViewer would require modifying flightgear/src/Viewer/fg_os_osgviewer.cxx and creating some kind of wrapper class that manages the CompositeViewer instance and assigns a CameraGroup to each osg::View. It's also important to note that currently all FG subsystems assume there is a single instance of CameraGroup.

Standardize the View manager Pending Pending

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/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/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/src/Viewer/view.cxx)

Create a Canvas Element subclass Pending Pending

1rightarrow.png See Canvas_Development#Adding_a_new_Element for the main article about this subject.

This derived class would require the following configuration:

  • Compositor to use.
  • 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 render a custom model. A typical use-case would be instruments that need to manipulate/render a 3D object (for which we have working code, too)
  • Several optimization/miscellaneous parameters like framerate cap, etc.

Simplifying a lot, this Canvas Element would be an aggregation of a Compositor instance, a View and a pointer to a osg::Group representing the scene graph to render. This setup could be replicated in flightgear/src/Viewer/fg_os_osgviewer.cxx, with the difference of ignoring Canvas and using native windowing features from OSG.

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