Yeah, I'm afraid you may have to do that. Once the double-buffer has been swapped to the screen, you can't draw on it anymore.
Some implementations may allow you to hint that you want a COPY swap, which leaves the buffer still intact in the back buffer after swap, so you could draw on it, but I don't think you can guarantee it. You probably want to RTT render the main scene to a texture, then to display it, just rasterize it onto a fullscreen quad each time. This makes it efficient to draw _any_ UI elements on top of it, without having to XOR (XOR is hard to see on mid-grey colors anyway) because you're actually clearing and re-blitting the texture on each update redraw. On Tue, Sep 24, 2013 at 6:26 PM, Andrew Cunningham <andr...@mac.com> wrote: > I am using a double-buffered window as per the OSG MFC example. > traits->doubleBuffer = true; The MFC example shows a nice overlay HUD of > rendering statistics. > > This just seems such a typical 3D UI interaction - to show a rectangular > area on the screen under mouse control for selection or zooming that it > surprises me there is not a canned solution. I suppose I could grab the > pixel buffer and make that a static background while I draw the rectangle. > It is crucial the full 3D scene be not continuously redrawn while drawing > this zoom box. > > ------------------ > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=56474#56474 > > > > > > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > -- Chris 'Xenon' Hanson, omo sanza lettere. xe...@alphapixel.com http://www.alphapixel.com/ Training • Consulting • Contracting 3D • Scene Graphs (Open Scene Graph/OSG) • OpenGL 2 • OpenGL 3 • OpenGL 4 • GLSL • OpenGL ES 1 • OpenGL ES 2 • OpenCL Digital Imaging • GIS • GPS • osgEarth • Terrain • Telemetry • Cryptography • Digital Audio • LIDAR • Kinect • Embedded • Mobile • iPhone/iPad/iOS • Android @alphapixel <https://twitter.com/alphapixel> facebook.com/alphapixel (775) 623-PIXL [7495]
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