Hi Christian, On 25 September 2014 16:35, Christian Buchner <[email protected]> wrote:
> when looking at the osgViewerBase class I noticed a feature where the user > can install "update operations" that get executed once per frame. > addUpdateOperation() is the function I am talking about. > > I was wondering if this method of updating the scene graph has any > advantages over the classic methods of installing update callbacks, or > updating things during the update traversal. > > The only two OSG examples making use of this feature are the osgtext > example and the osgthreadedterrain examples. Internally within OSG the > function isn't used anywhere, it seems. > The osg::OperationQueue that manages the update operations is a thread safe container that allows you to pass Operations from other threads to the viewer so that viewer can call then during the update traversal. Merging data built by a background thread is a good example of how one might use this facility. You can potentially do something similar with an update callback but it'd need to manage the thread safety etc. As conceptual note, scene graph Callbacks are really to do with the scene itself, such as animating an object, rather than viewer level operations. Robert.
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