Hi,
I'm building a little app that constructs PagedLOD nodes for a set of
terrain tiles based on their extents. The idea is to move around the
database and have certain tiles paged in and as I move away from them
have them paged out of memory.
Anyways, I've noticed that although I'm calling removeExpiredChildren()
on each of my PagedLOD objects some memory is being freed but a lot of
memory isn't. I'll move outside of the paging radius of all of my
tiles, for example, and the NodeList returned from
removeExpiredChildren() will indicate that the nodes have been removed
yet memory usage only appears to be going down slightly (and the nodes
are much quicker to page back in, probably because memory isn't being
freed).
I'm not sure what I'm doing wrong to cause (or not cause) the memory to
be freed. I have verified that getNumChildren() for each of the
PagedLOD's after I move away from all of the terrain segments goes to 0
(after removeExpiredChildren() is called). I'm running OSG 1.2. Here's
the basics of the code. Any advice would be appreciated.
==========
// Set up the viewer
osgProducer::Viewer viewer(args);
viewer.setUpViewer(osgProducer::Viewer::STANDARD_SETTINGS);
// Tell the viewer what to display for a help message
viewer.getUsage(*args.getApplicationUsage());
osg::ref_ptr<osg::Group> group = new osg::Group();
group->setName("plod toplevel node");
vector< osg::ref_ptr<osg::PagedLOD> > plods;
for(unsigned int i=0; i < terrain_filenames.size(); ++i)
{
// obtain center position
double radius = bboxes[i].radius();
osg::Vec3 center = bboxes[i].center();
// setup new lod
osg::ref_ptr<osg::PagedLOD> lod = new osg::PagedLOD();
lod->setName("plod for " + terrain_filenames[i]);
lod->setRangeMode(osg::LOD::DISTANCE_FROM_EYE_POINT);
lod->setFileName(0, terrain_filenames[i]);
lod->setCenter(center);
lod->setRadius(radius);
lod->setRange(0, 0.0f, bboxes[i].radius() * 5.0); // FIXME
group->addChild(lod.get());
}
// Optimize the scene
osgUtil::Optimizer optimizer;
optimizer.optimize(group.get());
// set the scene to render
viewer.setSceneData(group.get());
osg::Timer_t start_time = osg::Timer().tick();
osg::Timer_t last_output = osg::Timer().tick();
// Realize the viewer
viewer.realize();
while( !viewer.done() )
{
viewer.sync();
viewer.update();
//
// Debuging code to call removeExpiredChildren() every so often
//
osg::Timer_t cur_time = osg::Timer().tick();
if ( osg::Timer().delta_s(last_output, cur_time) > 0.2)
{
last_output = cur_time;
const double secs_since_start =
osg::Timer().getSecondsPerTick() * (cur_time - start_time);
double a_while_back = secs_since_start - 10.0;
if(a_while_back < 0) a_while_back = 0;
for(unsigned int i=0; i<group->getNumChildren(); ++i)
{
osg::NodeList nl;
osg::PagedLOD *lod = static_cast<osg::PagedLOD*>
(group->getChild(i));
bool removed_something =
lod->removeExpiredChildren(a_while_back, nl);
if(removed_something)
{
cout << "REMOVED STUFF. num children of lod " <<
lod->getName() << " is now " << lod->getNumChildren() << endl;
for(uint i=0; i<nl.size(); ++i)
{
cout << "nl[" << i << "] name = " << nl[i]->getName()
<< endl;
cout << "ref count = " << nl[i]->referenceCount() <<
endl;
}
}
}
}
--
Philip Lowman
Simulation Development Engineer, Modeling and Simulation Technology
General Dynamics Land Systems
http://www.gdls.com
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