Hello,
After much trying and failing, I think I have a fundamental
misunderstanding reagarding the DatabasePager. I have looked for
examples or code snippets and it seems that there are none. So here's
what I have.
I have a DatabasePager object that I use for terrain. When I need a new
chunk of terrain, I call requestNodeFile() with the name of the tile of
terrain that I want, and give it a group node to attach it to. Every
frame, I check my group nodes to see if they have a piece of terrain
attached to them (ie: see if the pager paged in the terrain and attached
it to my group). If a new piece of terrain has been loaded, I then
perform my initialization on it (lookup switch nodes, etc), and attach
it to my main scene. This gets the job done.
The problem now, is that every time a new tile is attached to the main
scene, the next frame takes a long time, and I have a missed frame. This
has to do with the new tile getting compiled (texture sent to OpenGL,
etc) when it's drawn the first time. To overcome this, I want
DatabasePager to do this for me, which it seems to be able to support,
but everything I try doesn't work in one way or another. I have
something like the following (roughly):
// Set up the pager
pager = osgDB::DatabasePager::create();
pager->setCompileGLObjectsForContextID (0, true);
pager->setDoPreCompile(true);
...
// My composite viewer
osgViewer::CompositeViewer *viewer = new osgViewer::CompositeViewer;
....
// Then for each View I have something like this.
view = new osgViewer::View;
view->setSceneData(root.get());
view->getScene()->setDatabasePager(pager);
So in this case, only what gets requested the first frame (before the
first draw) gets paged in. Anything requested after that never gets
loaded. If I take out the call to setCompileGLObjectsForContextID(), of
course, no precompiling happens. Other things happen if I take out the
getScene()->setDatabasePager().
From some of the code regarding PagedLOD's, I get the feeling I might
be going about this the wrong way entirely, and possibly using
DatabasePager in a way in which it was not designed.
So I guess my question is, does anyone have anything they can tell me
about how to use this class? Maybe some code snippets? Anything at all
would help. I've spent a lot of time searching online and digging
through the code, so if I've missed something obvious, please go easy :)
Alan.
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