Hi Robert -- I'm seeing a crash in the Optimizer with a large
proprietary model, and would greatly appreciate your input on a fix.
The crash is in MergeGeodes in both 2.8.2 and svn trunk head. I can
reproduce the problem with:
export OSG_OPTIMIZER=FLATTEN_STATIC_TRANSFORMS|MERGE_GEODES
osgconv largemodel.ive out.ive
But if I remove the FLATTEN_STATIC_TRANSFORMS and use only MERGE_GEODES,
there is no crash. Something about FLATTEN_STATIC_TRANSFORMS is causing
MERGE_GEODES to crash.
Here's what I know so far:
When OSG crashes, we're at Optimizer.cpp line 3079:
bool Optimizer::MergeGeodesVisitor::mergeGeode(osg::Geode& lhs,
osg::Geode& rhs)
{
for (unsigned int i=0; i<rhs.getNumDrawables(); ++i)
{
--> lhs.addDrawable(rhs.getDrawable(i));
}
return true;
}
The mergeGeodes function has been passed lhs and rhs which are
unfortunately the same Geode. This is causing an infinite loop of
addDrawable calls, until std::vector eventually throws an exception.
The structure of the subgraph at this point is a Group with two Geode
children, but they are both the same Geode. FLATTEN_STATIC_TRANSFORMS is
somehow creating this subgraph, because (as I noted above) the crash
goes away if I don't set FLATTEN_STATIC_TRANSFORMS.
MERGE_GEODES already has a mechanism for detecting duplicate Geodes, in
the function mergeGeodes(osg::Group& group). But it is not detecting the
same Geode added twice to a single Group parent.
So I'd like your advice on the fix.
It might be a mistake to add the same Geode twice to a parent, but I
don't believe there's anything in addChild to prevent this, so it'd be
nice if MERGE_GEODES would detect this condition and handle it
gracefully, print out a warning or something, but should not crash. So I
could modify the existing duplicate Geode check to look for and handle
this case. Do you agree?
Alternatively, or in addition, I could dig into the
FLATTEN_STATIC_TRANSFORM code and try to figure out how this subgraph is
being created in the first place. Then, when I have more info, we could
discuss a possible fix for FLATTEN_STATIC_TRANSFORMS. (Breaking for
lunch right now, will dig in this afternoon.)
Thoughts? Thanks for your time on this.
-Paul
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