Hi Ignacio, The osgdem app by default builds paged database, in fact this is really what its all about, creating a single scene graph with LOD's really is just a extra which comes effectively free from the implementation, and is mainly just used for testing - for serious usage one uses paged databases.
W.r.t paged databases, these are built top down as a quad tree, the topmost file contains the lowest level of detail geometry and textures, and also an external file reference for the next highest level of detail. At runtime you don't need to know about all the high res files, you just need to load the topmost file in the database and the OSG will automatically do the paging in on demand for you. The paging all takes its direction from the PagedLOD node, which are built into the database. Personally I'd recommend against trying to get to deep in working out how VPB does its stuff internally. First up its complicated and I'm waaay too over stretched to explain all the details. Second up, I'm just starting a massive refactor of VPB so what you see now won't necessarily apply to the future implementation. If you want to know more about PagedLOD and paging please trawl through the osg-users archives, there is lots of discussion over the years. Robert. On 8/7/07, Ignacio José López Rodríguez <[EMAIL PROTECTED]> wrote: > > Hi, > > I'm interested in knowing how is builded the scene graph by the "osgdem" > program. To this end, last week I'd reading the "Virtual Planet Builder" > code but I still have some doubts, specifically when the PAGED_LOD mode is > used. > > On the one hand, I'm able to follow how is linked the scene graph when the > simple LOD mode is set. If I'm not wrong it's instantiated a new LOD node > which in turn is composed of both a geometry node and a group of descendants > (if they are). Likewise its descendants are LODs node. > > However, when the PAGED_LOD mode is set I don't catch when nodes are linked > among them. That is, after reading the code it gives me the impression that > all nodes are written in the filesystem but I cannot see where they are > linked adn so where the scenegraph is builded. Likely, there is something > about the PAGED_LOD concept that I don't understand yet because I don't know > either why the QuadMap is used for the PAGED_LOD nodes instead of the > CompositeDestination graph. > > I'll appreciate any help. > > Thanks in advance, > > > > ________________________________ > > Sé un Mejor Amante del Cine > ¿Quieres saber cómo? ¡Deja que otras personas te ayuden! . > > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > > _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
