Hello Dusten,
From what I
understand about OSG's implementation of occlusion culling however, this
can't be accomplished with a single, large model used for the static
world geometry--as the camera is always within the bounding box.
OSG's culling is hierarchical, so if you organize your scene correctly
this will be done automatically. A very flat graph of large numbers of
objects is really bad, but a really deep graph is bad too, so you need
to experiment.
Say you're making a building, you could build a room, then parent all
rooms to form a floor, then parent all floors to form the building, then
add the outside walls.
When the viewer is in a room, for example, OSG will start at the top of
the graph, see that the bounds of the building as a whole are in view,
descend into the floors, cull away any floors whose bounds are not in
view, descend into the others, cull away any rooms whose bounds are not
in view, and render just the rooms whose bounds are in view (which
should hopefully be just the room you're in). It will also cull away
things that are behind the viewer or outside their field of view, so
walls and furniture behind you will be culled away.
Including your small objects into that hierarchy so that they're
parented to the right parent will lower draw times too. However, if you
have a very large number of small objects, you will want to cluster them
below a common Group parent, so that if the whole group's bounds are not
visible then it will be culled in one shot instead of testing each small
object's bounds individually. A symptom that indicates you should do
that is if your cull times are very high but your draw times are normal.
How many small objects to cluster together is a balancing act that you
should experiment with, as performance will depend on your hardware and
the current bottleneck in your pipeline.
There has been lots said in the past about how to properly balance a
scene graph, have a look through the archives. In general, it's called
"conditioning" a scene graph, and a scene graph that is badly balanced
is also called "badly conditioned", so you might want to search on those
terms.
Hope this helps,
J-S
--
______________________________________________________
Jean-Sebastien Guay [EMAIL PROTECTED]
http://www.cm-labs.com/
http://whitestar02.webhop.org/
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