Re: [osg-users] Safe downcast
Hello,
For the answer, I suggest you revise the C++ docs about dynamic_cast
and also check the class hierarchy of OSG's node types.
dynamic_castA* succeeds for any pointer to an object of class A or any
pointer to an object of a derived class of A. So even if you don't have
a proper Group at the root, if you have any object of a derived class of
Group (like osg::MatrixTransform, osg::Switch, etc.) it will succeed.
Check out Node::asGroup() (reimplemented in osg::Group) for an
alternative to dynamic_cast (trades a dynamic_cast which is pretty
costly for a virtual method call which is much less costly).
Hope this helps,
J-S
On 21/08/2012 3:49 PM, Peterakos wrote:
Hello.
I forgot to mention that i check it. That's why i posted it. Cause it
is very strange to run even though there is no group as root..
osg::ref_ptrosg::Group node =
dynamic_castosg::Group*(osgDB::readNodeFile( astroboy_walk.dae ));
if(!node) {
std::cout Model could not be loaded std::endl;
return 1;
}
thank you.
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Re: [osg-users] Safe downcast
Hi Peterakos, You should always check that the node set by the dynamic_cast is not NULL before doing any operation on it, this is a very basic programming practice, you shouldn't assume that the root node will always be a Group or a subclass from Group. Robert. On 20 August 2012 18:15, Peterakos hay...@gmail.com wrote: Hello. Thank you for your answer. Using an InfoVisitorNode, i can see there is not any group node as a parent. Even though that happens, i can still use addChild method in something that is not Group and has been passed through dynamic_cast. osg::ref_ptrosg::Group node = dynamic_castosg::Group*(osgDB::readNodeFile(astroboy_walk.dae)); node-addChild(createAxis()); I send the dae file too. thank you for your time. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Safe downcast
Hello.
I forgot to mention that i check it. That's why i posted it. Cause it is
very strange to run even though there is no group as root..
osg::ref_ptrosg::Group node =
dynamic_castosg::Group*(osgDB::readNodeFile( astroboy_walk.dae ));
if(!node) {
std::cout Model could not be loaded std::endl;
return 1;
}
thank you.
___
osg-users mailing list
osg-users@lists.openscenegraph.org
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] Safe downcast
Hello. In the example osganimationviewer in main there is the following line: osg::Group* node = dynamic_castosg::Group*(osgDB::readNodeFiles(arguments)); How safe is this if i use only 1 model in arguments and it is not Group ? Thank you for your time. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Safe downcast
On 08/20/2012 09:00 AM, Peterakos wrote: Hello. In the example osganimationviewer in main there is the following line: osg::Group* node = dynamic_castosg::Group*(osgDB::readNodeFiles(arguments)); How safe is this if i use only 1 model in arguments and it is not Group ? osgDB::readNodeFiles inserts a group at the root if there's more than one model loaded, but not when only a single model is loaded. There's a (rather slim) chance that your one model might not contain a Group (or Group descendant) at the root and that the dynamic_cast would result in a NULL. If you wanted to be absolutely sure, you could put in a check for this. Practically, almost every useful model (especially models with animations) will have some kind of group at its root. --J ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
