You know what would be great? If you submitted a very basic example of this to the osg-submissions mailing list, for inclusion in the osg examples directory. Even if it is a Windows-only example, this might be helpful for a lot of folks. Maybe someone else could extend it to work on Linux too.
2014-11-12 13:51 GMT+01:00 Chris Hidden <[email protected]>: > Just wanted to update this thread and provide information on how I > achieved what I was looking for. > > We managed to make a transparent application that you can click through > with OSG. This means that you can display models on the screen and have > them move around with regards to input and at the same time. The window is > always on top thus whatever your scene graph contains will always be > visible over top of any other application or window you have running at a > given time. Haven't tested all case scenarios but for any basic program > such as chrome or MS word etc.. this works. You can never focus the OSG > window so make sure you have a way of exiting the program. For development > we just use ESC at the moment. > > To do this you'll need to edit the GraphicsWindowWin32.cpp file in your > source. > > A few important parts are needed. In bool > GraphicsWindowWin32::createWindow() > > You will need to set the correct Windows and Windows Extended Styles: > > > Code: > > > ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// > windowStyle = WS_VISIBLE | WS_POPUP ; > /// > extendedStyle = WS_EX_LAYERED | WS_EX_TOPMOST | WS_EX_TRANSPARENT | > WS_EX_NOACTIVATE /// > > ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// > > > > > Extended Styles are key here.... topmost, layered and transparent. Also > no activate should disallow the user from being able to focus the window. > > The next part allows the window to be transparent using BlurBehindWindows > funcitonality. As far as I know this only works in windows 7 and above. > > > Code: > > DWM_BLURBEHIND bb = { 0 }; > HRGN hRgn = CreateRectRgn(0, 0, -1, -1); > bb.dwFlags = DWM_BB_ENABLE | DWM_BB_BLURREGION; > bb.hRgnBlur = hRgn; > bb.fEnable = TRUE; > bb.fTransitionOnMaximized = 0; > DwmEnableBlurBehindWindow(_hwnd, &bb); > > > > > Create the DWM_BLURBEHIND windows object. Set the area and flags and then > use the EnableBlur method to attach it to your window. > > Next we need to define the color key for what colors to omit so before the > end of the createWindow() method add: > > > Code: > > SetLayeredWindowAttributes(_hwnd, RGB(0, 0, 0), 0, LWA_COLORKEY); > > > > > Then we need to do some work to disallow the window to be controlled if > this is what you want. So in bool > GraphicsWindowWin32::realizeImplementation() > > We need to edit the if(!::SetWindowPos) conditional: > > > > Code: > > if (!::SetWindowPos(_hwnd, > HWND_TOP, > _windowOriginXToRealize, > _windowOriginYToRealize, > _windowWidthToRealize, > _windowHeightToRealize, > SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE)) > { > > reportErrorForScreen("GraphicsWindowWin32::realizeImplementation() - Unable > to show window", _traits->screenNum, ::GetLastError()); > return false; > } > > > > > Here adding SWP_NOACTIVATE is important. I believe the nosize and nomove > help as well but I haven't been able to determine if they actually have an > affect. > > Finally then in your scene youll need to set up your camera and viewer a > little differently. > > > Code: > > osg::ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer(); > // Set up your view however you want here. > osg::ref_ptr<osg::GraphicsContext::Traits> traits = new > osg::GraphicsContext::Traits(*viewer->getCamera()->getGraphicsContext()->getTraits()); > traits->alpha = true; > traits->doubleBuffer = true; > traits->blue = 8; > traits->red = 8; > traits->green = 8; > traits->depth = 24; > traits->windowDecoration = false; > osg::ref_ptr<osg::Camera> camera = new > osg::Camera(*viewer->getCamera()); > osg::ref_ptr<osg::GraphicsContext> graphicsContext = > osg::GraphicsContext::createGraphicsContext(traits.get()); > camera->setGraphicsContext(graphicsContext); > camera->setClearColor(osg::Vec4(.0,.0,.0,.0)); > camera->setClearMask(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT); > viewer->setCamera(camera.get()); > viewer->realize(); > > > // Add your scene > viewer->setSceneData(root); > > while (!viewer->done()) > { > viewer->frame(); > } > > > > > When setting up the traits, and camera we need to get them from the > existing window. So use the viewer object to obtain them. Make sure you > set the clear color and your GL Clear masks. Also don't forget to set the > camera object to your viewer object. > > Thats it! Hope this helps and I haven't missed to much. > > ------------------ > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=61586#61586 > > > > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >
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