The first bug is that the terrain tiles will page out to a lower LOD when they are right in front of you. The issue appears to be with the blacklisting heuristic which forces a tile to LOD 1, commenting out the usage of blacklisting with the LOD Nodes fixes our problem. This code change was made to line 29 of TXPPageLOD.cpp.
The second bug we were experiencing is that the database reader options never make it through to the archive loader. The use case for us appeared when the FID codes for the terrain were no longer on the materials. As it turns out the archive was being created twice, once by TXPNode and once by the ReaderWriterTXP on getArchive() so the options never actually got set on the archive that was being loaded. The fix is to first create the archive by calling getArchive on the ReaderWriterTXP, which stores it in a map for reference later, and then passing that archive into the TXPNode for it to set its internal member. With this code change we only create one archive (not sure what creating two did) and our options flags get set properly on the database.
The changes made are in TXPNode.h line 72 where the TXPArchive is now passed in. In the TXPNode.cpp the loadArchive(TXPArchive*) was changed to have the default behavior if NULL is passed in, if an archive is passed in then it does not load it since all the loading is done in the ReaderWriterTXP::getArchive(). The only other place that loadArchive is called is in TXPIO.cpp where a modification was made to pass in NULL which will have the same behavior as it used to. The last change is the little block of code starting on line 57 of ReaderWriterTXP.cpp, this was changed so that it first calls getArchive() which caches the archives in a map does some loading stuff and returns a pointer to it which is then passed in as a parameter to TXPNode::loadArchive().
The performance changes were made to TXPParser.cpp line 163 where we use to osgUtil::Optimizer on the node before passing it off, and on line 1456 we changed the geometry to use display lists. These small changes actually made drastic performance increases for us, as much as 1000% on certain laptops.
As far as testing goes, we have tested these changes with at least 5 txp databases on a variety of different computers including Mac OS and Linux. The base version used is 2.4."
email comments from Andew Sampson,
"I've contacted Terrex, and obtained the 2.2 version
of their trpage library. The library included a
fork of OSG 0.9.8's txp plugin, modified to load 2.1+
txp DBs.
I've done the work of incorporating the changes made
to OSG's txp plugin since 0.9.8 into Terrex's fork.
The forked version is now up-to-date with the changes
made to OSG 0.9.9 and 1.0.
Terrex made a lot of changes (especially differences
in whitespace), so the diff between the forked version
and OSG 1.0's txp plugin is yucky. I did my best, but
keep in mind that this is the result of a 4-way merge
(kinda... terrex-0.9.8, stock-0.9.8, stock-0.9.9,
stock-1.0).
I really want to see this forked version merged back
into the main OSG branch. The new features offered by
this version of the plugin (2.1+ support, variable
LOD support, bug fixes) are worth the trouble."
--
Don Tidrow then took this code and added his work.
--
Robert Osfield then fixed all the warnings that abound in the trpage code base.
discovered that TXPNodes were being culled out prematurely because the
loaded sub-tiles resulted in a computed bounds that was smaller than the
extents indicated in the archive. I think this fix should be fine. I can't
think of any reason why we would want to use anything other than the archive
extents."
