On Monday 27 Feb 2012 19:49:53 Jean-Sébastien Guay wrote: > Hi Magnus, > > > But maybe this question is more to the authors of osgmaxexporter. Why > > does osgmaxexporter unconditionally set the data variance to STATIC? > > What are the use cases where one would model a STATIC DOFTransform? > > DOFTransforms are a relic of Multigen (Presagis) Creator, and in that > software they were the most widely used transform node. Modelers (as you > probably know) are fond of putting lots of transforms (and groups) all > over the scene graph, to keep things understandable to them, and to make > it easier to modify the model later. > > Unfortunately, there are often many of these transforms that aren't > really useful once the models are in the simulation software. So yes, > there is a valid use case for static DOFTransforms - transforms that > were just put there by the modeler for convenience, but which don't have > any use in simulation. > > Now, I agree with you, the STATIC data variance should not be > unconditionally applied. There can be rules to determine when it should > be, for example if the DOFTransform does not have any limits. > > At my previous employer, we had made a custom osgconv which would > "massage" the scene graph before calling the osgUtil::Optimizer on it (I > think I mentioned this before on this list). This "massage" is highly > dependent on what you'll be doing with your data, which is why I don't > think it would be useful to submit such a thing - OSG provides the tools > for you to do the right thing in your situation. But just as an example, > our tool would: > > * Normalize state to expected values (we didn't require artists to set > the right filtering or face culling manually, we enforced it in the > tools, so that osgUtil::Optimizer's various merge operations could give > good results) > * Flag nodes as dynamic if we didn't want them optimized away (we had > various rules, including if a comment contained "Dynamic", if a DOF had > limits, etc. > * Remove most Group nodes since these just hinder the merge visitors and > in most cases, better batching (less draw calls) is more important than > better spatial culling. > > Again, I've talked about these things in the past, and others have > shared similar or related advice too. > > Hope this helps, > > J-S
Thanks, Jean-Sebastien, for your detailed explanation. You've effectively confirmed what I suspected. In our workflow, where DOFTransforms are only occasionally used for a very specific purpose they should never be marked STATIC in the first place. I believe that this is true for all workflows where DOFTransforms are being added through the osgmaxexporter. There they require a conscious decision of the modeller to add them to the scene through a special osgmaxexporter helper object. And as modellers don't really like to use functionality that is not native to their tool until they absolutely have no other choice an accidental use is rather improbable. I'll patch osgmaxexporter and take it from there. Thanks everyone for their contributions on this thread. Magnus _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
