Hi Robert,
thank you very much. Now i can use the latest SVN version and my application
still works fine. I guess this prototype
archi is quite good. i didn't know this implementation.
I am not sure if we have to foce the user pass through the create method. if
a user has to change the behaviour of such a very low-level
class, it should be aware what is going on by handling this.
/regards adegli
2007/8/8, Robert Osfield <[EMAIL PROTECTED]>:
>
> Hi Adrian,
>
> I have just checked in a trial of using localised prototype()/create()
> methods added to CullVisitor and DatabasePager. The added methods
> look like:
>
> /** Create a shallow copy of the CullVisitor, used by
> CullVisitor::create() to clone the prototype..*/
> virtual CullVisitor* clone() const { return new
> CullVisitor(*this); }
>
> /** get the prototype singleton used by CullVisitor::create().*/
> static osg::ref_ptr<CullVisitor>& prototype();
>
> /** create a CullVisitor by cloning CullVisitor::prototype().*/
> static CullVisitor* create();
>
> The DatabasePager is exactly the save for class name. The
> implementation looks like:
>
> osg::ref_ptr<CullVisitor>& CullVisitor::prototype()
> {
> static osg::ref_ptr<CullVisitor> s_CullVisitor = new CullVisitor;
> return s_CullVisitor;
> }
>
> CullVisitor* CullVisitor::create()
> {
> return CullVisitor::prototype().valid() ?
> CullVisitor::prototype()->clone() :
> new CullVisitor;
> }
>
> Things to note are the fact that the prototype method passed back a
> reference to the static ref_ptr<CullVisitor>, this allows you to
> directly modify it without the need for a set/get pairing.
>
> To pass on your own implementations you'll need to something like the
> following (note, the copy constructor and clone() method being
> overriden):
>
> class MyCullVisitor : public osgUtil::CullVisitor
> {
> public:
>
> MyCullVisitor()
> {
> osg::notify(osg::NOTICE)<<"Constructig my CullVisitor
> "<<this<<std::endl;
> }
>
> MyCullVisitor(const MyCullVisitor& rhs):
> CullVisitor(rhs)
> {
> osg::notify(osg::NOTICE)<<"Constructig my
> CullVisitor(CullVisitor)"<<this<<std::endl;
> }
>
> ~MyCullVisitor()
> {
> osg::notify(osg::NOTICE)<<"Destructig my
> MyCullVisitor"<<this<<std::endl;
> }
>
>
> virtual CullVisitor* clone() const { return new MyCullVisitor(*this);
> }
>
> void apply(osg::Geode& geode)
> {
> // osg::notify(osg::NOTICE)<<"In
> MyCullVisitor::apply(Geode)"<<std::endl;
> CullVisitor::apply(geode);
> }
> };
>
> class MyDatabasePager : public osgDB::DatabasePager
> {
> public:
>
> MyDatabasePager()
> {
> osg::notify(osg::NOTICE)<<"Constructig my
> MyDatabasePager"<<std::endl;
> }
>
> MyDatabasePager(const MyDatabasePager& rhs):
> DatabasePager(rhs)
> {
> osg::notify(osg::NOTICE)<<"Constructig my
> MyDatabasePager"<<std::endl;
> }
>
> ~MyDatabasePager()
> {
> osg::notify(osg::NOTICE)<<"Destructig my
> MyDatabasePager"<<std::endl;
> }
>
> virtual DatabasePager* clone() const { return new
> MyDatabasePager(*this); }
>
> };
>
>
> int main(int argc, char** argv)
> {
> osgUtil::CullVisitor::prototype() = new MyCullVisitor;
> osgDB::DatabasePager::prototype() = new MyDatabasePager;
>
> .. usual set up of your application, osgViewer will now use these
> prototypes..
>
> }
>
> Attached is osgviewer.cpp modified with these changes.
>
> The reason for me going for this solution is simply to keep the
> factory method localised to each class, and it also offers the
> possibility of configuring the original prototype without needing to
> create a new instance.
>
> A further evolution might be to make the default and copy constructors
> of CullVisitor/DatabasePager pager protected to force developers to go
> via the create() method, but this would prevent some types of usage so
> I'll hang back on this.
>
> Robert.
>
> _______________________________________________
> osg-users mailing list
> osg-users@lists.openscenegraph.org
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>
>
>
--
********************************************
Adrian Egli
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