Frequently Asked Questions

Questions:

1. How do I make the test programs?

2. Why do my 1.0 programs crash on 1.1 and later?

3. How do I set the name of an object?

4. Why does multithreading/clustering/change list access not work anymore?

Answers:

1. How do I make the test programs?

   Configure will create a directory in the Builds hierarchy for your system. In that directory you will find different directories for building the libraries (BaseLib, SystemLib etc.) and the test programs (BaseTest, SystemTest etc.). Go into the ...Test directory and say make to create all tests, make list gives you a list of the possible tests.

2. Why do my 1.0 programs crash on 1.1 and later?

   One of the major changes that we made was a revamp of the reference counting system. As a consequence the UnlinkSubTree and friends methods are not needed any more, subRefCP() is fine and will destroy the tree if it's not used anywhere else. But as a consequence you will have to make sure to addRefCP() objects that you want to be kept around, especially if you move them in and out of the tree. A simple subChild() will decrement the refcount and delete the object if it's not refed anywhere else. A rule of thumb would be to addRefCP all the objects that you keep a pointer to in your own code and be careful when moving objects around in the tree. The easy way is to leave the burden on the system and just add the node to the new parent. As we only have single parents it will automatically be removed from the original parent and moved to the new one, taking care of the refcounts.

3. How do I set the name of an object?

   Names in OpenSG are done via osg::Attachment classes. As names are a quite common problem, there are convenience functions osg::getName(void) and osg::setName(const Char8 *) in OSGSimpleAttachments.h. See the attachment tutorial for more info on using names and attachments in general.

4. Why does multithreading/clustering/change list access not work anymore?

   After 1.2 it was decided to switch the osg::ChangeList to read-only by defulat, to prevent an annoying memory leak in applications that don't care about multi-threading and never clear their change list. To turn it to read-write you need to add the following code snippet before osgInit:

   #if OSG_MINOR_VERSION > 2
       ChangeList::setReadWriteDefault();
   #endif
   

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