Hi Robert, Sure, I can use a dedicated scene graph, but the other key aspect here is I really want to avoid drawing that scene anywhere [when I say this intersection test is in my rendering loop it's because I'm actually rendering *another scene*, but not this one]. It that currently possible out of the box ? Or is there a simple way to just prevent the camera drawing traversal ?
=> What I have in mind is: as long as I don't try to render anything on screen I won't have to take into account any kind of hardware compatibilty issue (since I won't have to rely on any kind of OpenGL call and will rather manipulate only an "in memory scene graph". This would ensure the highest possible compatibility with various hardware configurations with no cost since I'm just not interested in actually seeing this 3D earth model. Cheers, Manu. 2011/6/15 Robert Osfield <[email protected]> > Hi Manu, > > On Wed, Jun 15, 2011 at 9:49 AM, Emmanuel Roche > <[email protected]> wrote: > > I understand this as nothing to do with rendering, but it has to do with > > loading all tiles in a row instead of loading them only when there is > some > > time available between two frames as the databasepager does. Since the > > intersection is done for me in the rendering loop this is blocking > > everything for too long. > > Doing intersections in the rendering loop should only be done with no > external file excees - the DatabasePager loads in a background thread > to prevent any stalls. For you case you either need to stop using > LineOfSight with the it's file cache callback installed, or move the > intersections tests entirely out of the rendering loop and do it a > background thread. > > In fact, I need the highest possible resolution. But I would not mind > > getting this final accurate result after multiple cycles (as would be the > > case if I let the database pager load the tiles progressively. So I > guess, > > just putting a camera very close to the ground on the intersection ray > would > > be a good option. > > Hacking around with the camera won't address the basic problem - if you > want the highest level of detail for interesection you have to load them, > and > loading them takes time - this simply doesn't mix with a real-time > rendering > loop. You can't be "clever" and avoid this, it's an intractable problem > that > can only be resolved by moving the intersections out of the rendering loop > into it's own dedicated intersection thread. > > > => Now, could I really just setup a Cullvisitor manually, traverse the > scene > > with this visitor, and then perform a updateSceneGraph() call on a > regular > > basis with the databasepager, and except the tiles to be progressively > > loaded this way ? > > You can't solve the problem this way. > > You *have* to move the interesection testing outside of the main > rendering thread. Consdier using an enterily dedicated scene graph > for just this purpose, running it's own threads. > > Robert. > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >
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