sherman wilcox wrote:
> Ok. Thanks for the reply. Followup question: Is there an automagic way
> to determine what this last camera is or do I need to keep track of
> that myself?
>
> Is it reasonable to attach a camera to the scenegraph set as the
> "last" camera just for capture purposes? I wouldn't think there would
> be much overhead incurred, but never hurts to ask.
Sherman,
I'm still learning how to fully use OSG myself, but here's the skeleton
code I wrote (based on the "osghud" and other examples).
[If anyone more experienced has any corrections/improvements to this
code, we'd all appreciate it].
This code "works for me" in my application, and will hopefully be easier
for you to get going with than the 3-styles-in-one osghud example (it
took me a few hours of testing settings and reading docs to figure out
exactly what was needed for each of the 3 display styles used in that
example).
The setRenderOrder(osg::Camera::POST_RENDER) on the HUD scene basically
makes it the "last" camera since all other scenes will be rendered
before this one.
I personally wouldn't bother with a screenshot-only camera as it will be
extra overhead and the HUD camera is basically IS that camera with some
display widgets in it.
[PS: and while the code below is from working code on my system, I did
strip out some app-specific parts for this email. If it doesn't compile
as a result, my apologies, and I can help if the fix isn't obvious].
- Michael
// ==========
osgViewer::CompositeViewer viewer;
// Main view
{
osg::ref_ptr<osgViewer::View> view = new osgViewer::View();
view->setUpViewAcrossAllScreens();;
view->setSceneData(root.get()); // root node of main scene here
// black background for the main scene
view->getCamera()->setClearColor(osg::Vec4(0.00, 0.00, 0.00, 1.00));
view->addEventHandler(new osgViewer::WindowSizeHandler());
view->addEventHandler(new osgViewer::StatsHandler());
view->addEventHandler(new osgViewer::HelpHandler());
viewer.addView(view.get());
}
// get window info from main view
osgViewer::Viewer::Windows windows;
viewer.getWindows(windows);
if (windows.empty()) {
return 1;
}
// HUD view (overlaid on main view)
{
osg::ref_ptr<osgViewer::View> view = new osgViewer::View();
view->setSceneData(hud.get()); // root node of hud scene here
view->getCamera()->setGraphicsContext(windows[0]);
view->getCamera()->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
view->getCamera()->setProjectionMatrix
(osg::Matrix::ortho2D(0,1600,0,1200));
view->getCamera()->setViewport(0, 0,
windows[0]->getTraits()->width,
windows[0]->getTraits()->height);
view->getCamera()->setViewMatrix(osg::Matrix::identity());
// draw this scene after the main scene (it's the "last" camera)
view->getCamera()->setRenderOrder(osg::Camera::POST_RENDER);
// no background (clear) so the main scene shows through
view->getCamera()->setClearMask(GL_DEPTH_BUFFER_BIT);
// Don't let the HUD camera grab event focus from the
// main view's camera.
view->getCamera()->setAllowEventFocus(false);
// Attach your screen capture draw callback here
drawcallback_screenshot = new DrawCallback_Screenshot("screenshot");
view->getCamera()->setPostDrawCallback
(drawcallback_screenshot.get());
viewer.addView(view.get());
}
return (viewer.run());
// ==========
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