Hi, Neil I feel like (b) option is a clear winner here.If it is possible to make osg context shared with CAOpenGLLayer, you'll be in good shape and running without gpu->ram->gpu transfers. Otherwise it all depends on texture roundabout impact on framerate.
Cheers, Sergey. 24.08.2012, 18:36, "Neil Clayton" <n...@shinywhitebox.com>: > Hi All, > > I've a question or two regarding rendering contexts. While the usage is OSX > specific, the question is not. > > I'm rendering into a CAOpenGLLayer (I can't render directly to a NSOpenGLView > because I'm also using CALayer objects within the view - and these conflict > with the NSOpenGLView, at least in my experience). > > In essence this means I manage the OpenGL context, create an osg::Viewer and > use the setupViewerAsEmbeddedInWindow method. I have no problem using the > context created by CAOpenGLLayer (I'm basing my code on the existing > CocoaViewer which essentially does the same thing), I do have problems when > the context which OSG is now using needs to be reset. > > In CAOpenGLLayer, a context reset can be caused by (for example) a user > moving the window to another screen. In this case the context might be > recreated because CAOpenGLLayer wants to use either a different graphics card > or a different pixel format. > > From what I can gather, while I'm managing the real OpenGL context myself, > OSG is managing it's own texture ID's (and I presume other scene OpenGL > resources). When the real OpenGL context is reset, OSG still believes all of > it's existing resources to be valid, because I've not explicitly told it > otherwise. > > From this I have two questions: > a) How do I tell OSG to throw away it's managed resources (texture ID's, > etc), such that they are recreated at the next render pass? Can I do this? > Is it even wise? Or should I be looking to throw away the viewer and recreate > it? > > b) Instead of the above, should I rather have OSG manage it's own context and > then after each OSG render pass copy the rendered result to the layer? > > For (b) I was considering rendering to a texture backed FBO, then DMA'ing > that texture to RAM. I'd then DMA that back into the CAOpenGLLayer context. > Thus OSG wouldn't have to be concerned at all with what the layer is with > it's context, nor context resets. This (to me) sounds like a reasonable > idea. It'd keep the OSG engine separated from the CAOpenGLLayer side of > things, and would allow OSG to manage everything about it's rendering > pipeline. The only part I don't like is the additional texture-copy to get > the result into another context. > > p.s: The scene being drawn is small, with only many hundreds of vertices and > <100 textures. > > Thank you! > > Cheers, > Neil > > ------------------ > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=49508#49508 > > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
