Hi Robert,
I've made a small fix to osgViewer/Scene.cpp, which is already attached. I
would like to explain what I've done and why.
In Scene::updateSceneGraph(), change:
if (getSceneData())
{
updateVisitor.setImageRequestHandler(getImagePager());
getSceneData()->accept(updateVisitor);
}
if (getDatabasePager())
{
// synchronize changes required by the DatabasePager thread to the
scene graph
getDatabasePager()->updateSceneGraph((*updateVisitor.getFrameStamp()));
}
to
if (getDatabasePager())
{
// synchronize changes required by the DatabasePager thread to the
scene graph
getDatabasePager()->updateSceneGraph((*updateVisitor.getFrameStamp()));
}
if (getSceneData())
{
updateVisitor.setImageRequestHandler(getImagePager());
getSceneData()->accept(updateVisitor);
}
That is, just swap the positions of two 'if () {...}' segments.
While working on a paged terrain, I need to collect every newly allocated
PagedLODs and make them temporarily unrenderable in the next frame,
which are all done in a update callback. But I found that these PagedLODs
will always be shown before collecting them, because of the unsuitable
sequence in Scene::updateSceneGraph(). DatabasePager is synchronized AFTER
the user updating traversal, that is, user cannot IMMEDIATELY find
out changes made by DatabasePager.
I don't know if there are other concerns that force us put the user
traversal before updating DatabasePager. But I think it will be easier for
users to manage the scenegraph, especially paged objects, if swap these two
processes. What's your opinion? :)
Cheers,
Wang Rui
/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
*
* This library is open source and may be redistributed and/or modified under
* the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
* (at your option) any later version. The full license is in LICENSE file
* included with this distribution, and on the openscenegraph.org website.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* OpenSceneGraph Public License for more details.
*/
#include <osgViewer/Scene>
#include <osgGA/EventVisitor>
using namespace osgViewer;
typedef std::vector< osg::observer_ptr<Scene> > SceneCache;
static OpenThreads::Mutex s_sceneCacheMutex;
static SceneCache s_sceneCache;
Scene::Scene():
osg::Referenced(true)
{
setDatabasePager(osgDB::DatabasePager::create());
setImagePager(new osgDB::ImagePager);
OpenThreads::ScopedLock<OpenThreads::Mutex> lock(s_sceneCacheMutex);
s_sceneCache.push_back(this);
}
Scene::~Scene()
{
OpenThreads::ScopedLock<OpenThreads::Mutex> lock(s_sceneCacheMutex);
for(SceneCache::iterator itr = s_sceneCache.begin();
itr != s_sceneCache.end();
++itr)
{
Scene* scene = itr->get();
if (scene==this)
{
s_sceneCache.erase(itr);
break;
}
}
}
void Scene::setSceneData(osg::Node* node)
{
_sceneData = node;
if (_databasePager.valid())
{
// register any PagedLOD that need to be tracked in the scene graph
if (node) _databasePager->registerPagedLODs(node);
}
}
osg::Node* Scene::getSceneData()
{
return _sceneData.get();
}
const osg::Node* Scene::getSceneData() const
{
return _sceneData.get();
}
void Scene::setDatabasePager(osgDB::DatabasePager* dp)
{
_databasePager = dp;
}
void Scene::setImagePager(osgDB::ImagePager* ip)
{
_imagePager = ip;
}
void Scene::updateSceneGraph(osg::NodeVisitor& updateVisitor)
{
if (!_sceneData) return;
if (getDatabasePager())
{
// synchronize changes required by the DatabasePager thread to the
scene graph
getDatabasePager()->updateSceneGraph((*updateVisitor.getFrameStamp()));
}
if (getSceneData())
{
updateVisitor.setImageRequestHandler(getImagePager());
getSceneData()->accept(updateVisitor);
}
if (getImagePager())
{
// synchronize changes required by the DatabasePager thread to the
scene graph
getImagePager()->updateSceneGraph(*(updateVisitor.getFrameStamp()));
}
}
Scene* Scene::getScene(osg::Node* node)
{
OpenThreads::ScopedLock<OpenThreads::Mutex> lock(s_sceneCacheMutex);
for(SceneCache::iterator itr = s_sceneCache.begin();
itr != s_sceneCache.end();
++itr)
{
Scene* scene = itr->get();
if (scene && scene->getSceneData()==node) return scene;
}
return 0;
}
Scene* Scene::getOrCreateScene(osg::Node* node)
{
if (!node) return 0;
osgViewer::Scene* scene = getScene(node);
if (!scene)
{
scene = new Scene;
scene->setSceneData(node);
}
return scene;
}
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