[osg-users] automatically merge close-by geometries to reduce cull/draw overhead?

[Christian Buchner]

Hi,

we're using code loading some buildings (outline and height), creating a
Geode with a two drawables per individual building - one drawable for the
walls, one for the roof polygon. This has served us well to display a few
hundred to a few thousand buildings.

Fast forward to current date. Our client has sent us a new geo data set
containing 55000 building polygons. Once you zoom out the camera to show
most of these buildings, frame rates drop into the low single digit, mostly
due to all the culling effort done by the CPU (maybe also from the large
number of draw calls). D'oh!

Are there any specific features within OSG to group close by geodes, and to
merge their drawables?

I know the osgUtil::Optimize has flags for merging geodes and drawables,
but I guess it would not automatically merge only very close objects.

What path should I try to take for tackling this problem, if possible using
built-in OSG features?

Christian
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