forcing users to use osgDB::readRef*File() methods. The later is preferable as it closes a potential threading bug when using paging databases in conjunction
with the osgDB::Registry Object Cache. This threading bug occurs when one thread gets an object from the Cache via an osgDB::read*File() call where only
a pointer to the object is passed back, so taking a reference to the object is delayed till it gets reassigned to a ref_ptr<>, but at the same time another
thread calls a flush of the Object Cache deleting this object as it's referenceCount is now zero. Using osgDB::readREf*File() makes sure the a ref_ptr<> is
passed back and the referenceCount never goes to zero.
To ensure the OSG builds when OSG_PROVIDE_READFILE is to OFF the many cases of osgDB::read*File() usage had to be replaced with a ref_ptr<> osgDB::readRef*File()
usage. The avoid this change causing lots of other client code to be rewritten to handle the use of ref_ptr<> in place of C pointer I introduced a serious of
templte methods in various class to adapt ref_ptr<> to the underly C pointer to be passed to old OSG API's, example of this is found in include/osg/Group:
bool addChild(Node* child); // old method which can only be used with a Node*
tempalte<class T> bool addChild(const osg::ref_ptr<T>& child) { return addChild(child.get()); } // adapter template method
These changes together cover 149 modified files, so it's a large submission. This extent of changes are warrent to make use of the Object Cache
and multi-threaded loaded more robust.
git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/branches/OpenSceneGraph-3.4@15165 16af8721-9629-0410-8352-f15c8da7e697
circumstances under which this bug occur are rather specific, but the
basic problem occurs when one translation unit other than libosg.so
constructs an object that is a subclass of osg::Shape and another
translation unit other than libosg.so tries to perform a dynamic_cast or
other RTTI-based operation on that object. Under these circumstances,
the RTTI operation will fail. In my case, the translation units involved
were an application and osgdb_ive.so. The application constructed a
scene graph that included instantiations of subclasses of osg::Shape.
Depending on how the user ran the application, it would write the scene
graph to an IVE file using osgDB::writeNodeFile(). The dynamic_cast
operations in DataOutputStream::writeShape() would fail on the first
subclass of osg::Shape that was encountered. This is because there were
two different RTTI data objects for all osg::Shape subclasses being
compared: one in the application and one in osgdb_ive.so.
The fix for this is simple. We must ensure that at least one member
function of each of the subclasses of the polymorphic type osg::Shape is
compiled into libosg.so so that there is exactly one RTTI object for
that type in libosg.so. Then, all code linking against libosg.so will
use that single RTTI object. The following message from a list archive
sort of explains the issue and the solution:
http://aspn.activestate.com/ASPN/Mail/Message/1688156
While the posting has to do with Boost.Python, the problem applies to
C++ libraries in general."
it to be assigned as a vertex attribute array to an osg::Geometry.
Removed the osgTerrain::ArrayLayer as its no longer required thanks to the above change
which makes the osgTerrain::HeightFieldLayer more flexible.
Updated wrappers
that they arn't created on the stack inappropriately.
Split the implemention of Matrix up so that it is a simple no referenced counted
class and can be safefly created on the stack. To support referenced counting a
seperate subclass now exists, this is RefMatrix which inherits from both Matrix and
Object.
