Not sure why you would need to place the vegetation _exactly_ on the ground
for anything other than the highest LOD. Presumably, for lower LODs, the
eyepoint would be too distant to notice any issues. If you agree, then you
could use an LOD=savvy tool like ElevationSlice to get the elevation of the
highest LOD, and place your vegetation there and not bother trying to change
it.

Hope that helps,

Paul Martz
Skew Matrix Software LLC
http://www.skew-matrix.com
+1 303 859 9466

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Jan
Sent: Tuesday, May 05, 2009 2:38 AM
To: [email protected]
Subject: [osg-users] Problem with Cullvisitor


Hi,

first of all, i'd like to introduce you to my problem to you.
I have a PagedLOD DB for representing the ground.
On this ground I want to position vegetation also as PagedLOD Nodes. X and Y
Values are fix. 
The Problem is that I have to set the vegetation exactly on the ground,
using an intersectiontest works, but if the ground tiles switch from one
level to the other, the position needs to be recalculated because there
might be gaps when getting finer tile resolution.
My first idea was to use osgDB::Registry::ReadFileCallback to check if a
node is paged in. But this doesn't seem to work because the databasepager
has cached tiles and so changing isn't registered. The second idea was to
use a cullvisitor to update all visible vegetation. But if I attach
setCullCallback to a vegetation-node the cullvisitor works just for the root
node. Then I thought of setting CullCallback to all children while  creating
them. But then this information will be lost because they need to be saved.
I hope it is clear what I'm trying to do.
Has anyone an idea how to handle this problem or possibly an other approach?



Thank you.

------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=11331#11331





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