Re: [osg-users] osgUtil::Optimizer and osgSim::DOFTransform with data variance STATIC
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 osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] osgUtil::Optimizer and osgSim::DOFTransform with data variance STATIC
We recently discovered that osgSim::DOFTransform nodes were unexpectedly removed from the scene graph by the unconditional use of the osgUtil::Optimizer in osgconv. The DOFTransform nodes were marked by our modelling tool (Max with the osgmaxeporter plugin) as STATIC. Should the optimizer flatten DOFTransform nodes at all, under any circumstances? They carry much more information than a simple transformation matrix, such as the ranges for the DOFs. In our case it was this information that needed to be preserved. Can anyone think of a good use case where one would want to flatten DOFTransform nodes with osgconv? After all, if I weren't interested in the additional information, I could just use a MatrixTransform... Regards, Magnus ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] osgUtil::Optimizer and osgSim::DOFTransform with data variance STATIC
HI Magnus, If you make a Transform node as STATIC then you've told the scene graph that it will never change so will be fair game for the Optimizer. You have two choices if you don't want to have the Optimizer optimize it away: 1) Don't call the Optimizer with the FLATTEN_STATIC_TRANSFORM enabled. 2) Make your Transforms which will be changing as DYNAMIC. Robert. On 27 February 2012 15:10, Magnus Kessler magnus.kess...@gmx.net wrote: We recently discovered that osgSim::DOFTransform nodes were unexpectedly removed from the scene graph by the unconditional use of the osgUtil::Optimizer in osgconv. The DOFTransform nodes were marked by our modelling tool (Max with the osgmaxeporter plugin) as STATIC. Should the optimizer flatten DOFTransform nodes at all, under any circumstances? They carry much more information than a simple transformation matrix, such as the ranges for the DOFs. In our case it was this information that needed to be preserved. Can anyone think of a good use case where one would want to flatten DOFTransform nodes with osgconv? After all, if I weren't interested in the additional information, I could just use a MatrixTransform... Regards, Magnus ___ 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] osgUtil::Optimizer and osgSim::DOFTransform with data variance STATIC
On Monday 27 Feb 2012 15:26:15 Robert Osfield wrote: HI Magnus, If you make a Transform node as STATIC then you've told the scene graph that it will never change so will be fair game for the Optimizer. You have two choices if you don't want to have the Optimizer optimize it away: 1) Don't call the Optimizer with the FLATTEN_STATIC_TRANSFORM enabled. 2) Make your Transforms which will be changing as DYNAMIC. Robert. Hi Robert, Thanks for your rapid answer. I understand perfectly well the way the optimizer works and how to get the desired behaviour in its current implementation. DYNAMIC DOFTransform is the way to go (FLATTEN_STATIC_TRANSFORMS wouldn't work, as these DOFTransform nodes are part of bigger scenes, that do benefit from transformation flattening). I was just trying to see if there was a good reason to ever set the data variance to STATIC on a DOFTransform. 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? Magnus ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] osgUtil::Optimizer and osgSim::DOFTransform with data variance STATIC
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 -- __ Jean-Sebastien Guay jean_...@videotron.ca http://whitestar02.dyndns-web.com/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
