Re: [osg-users] Modifying scenegraph and update
Hi Jimmy, The OSG doesn't support general multi-threaded update, you have to serialize all the updates and make sure they happen during the update phase of the frame. Support for general mult-threaded update would complicate the scene graph design, implementation, usage and have a big hit on performance, so it's something I've strongly avoided. It isn't difficult to manage applications so that they do single threaded update, which route is best for you will depend upon your needs. You don't provide any information about what you are trying to do and why so it's rather too open ended to go suggest what you should do. Robert. On Tue, Jun 1, 2010 at 5:47 AM, Jimmy Lin dummy...@gmail.com wrote: Hi, On relative issue. What if viewer-frame() is running on different thread that is different to the thread that modifies the scene graph. In that case I don't really have the control when is frame() get called. the modification can happen during the rendering time, which I guess is bad. I tried use lock/unlock wrap around frame() and where ever I modify the scene, but this introduce serious performance issue. The only solution I can think of is use UpdateCallback. but wouldn't the same problem happens when modify the update callback at the same time as frame() doing the updatetraversal? or does OSG have a way to protect the data during the updatetraversal ?? Or is there other approach you can advice me. Thank you! Cheers, Jimmy -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=28388#28388 ___ 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] Modifying scenegraph and update
Hi, On relative issue. What if viewer-frame() is running on different thread that is different to the thread that modifies the scene graph. In that case I don't really have the control when is frame() get called. the modification can happen during the rendering time, which I guess is bad. I tried use lock/unlock wrap around frame() and where ever I modify the scene, but this introduce serious performance issue. The only solution I can think of is use UpdateCallback. but wouldn't the same problem happens when modify the update callback at the same time as frame() doing the updatetraversal? or does OSG have a way to protect the data during the updatetraversal ?? Or is there other approach you can advice me. Thank you! Cheers, Jimmy -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=28388#28388 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Modifying scenegraph and update
Martin Beckett writes: I am modifying the scene, adding geometries, vertices etc and i have no control over when a draw traversal takes place. I am being carefull to ensure the geometry is always valid, eg. by adding vertices first then updating the PrimitiveSet but none of these operations are really atomic. Is there some lock/unlock mechanism in OSG or I is it happening by magic? This is done through the method Object::setDataVariance(), setting it to STATIC or DYNAMIC. In your case, you should mark that object DYNAMIC in order to prevent OSG accesing it while you are modifying the mesh. -- Alberto ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Modifying scenegraph and update
Thanks - I think I am misunderstanding the threading in OSG. In the gui I though frame() was called at 60fps, eg with a model rotating in the view. If I have a gui thread (say a non-modal dialog) that modifies the scene then I need to make sure that I don't have an invalid drawable/vertex array combination at any point. In my own code I was used to having a semaphore that prevented a repaint while the data was being modified - but didn't see anything like that in OSG I will take a look at the suggestion Cheers, Martin -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=25260#25260 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Modifying scenegraph and update
Is there some lock/unlock mechanism in OSG or I is it happening by magic? This is done through the method Object::setDataVariance(), setting it to STATIC or DYNAMIC. In your case, you should mark that object DYNAMIC in order to prevent OSG accesing it while you are modifying the mesh. Not exactly, just setting a node as DYNAMIC doesn't mean the app can safely alter a node at any time. See the OSG QuickStartGuide. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Modifying scenegraph and update
Is there some lock/unlock mechanism in OSG or I is it happening by magic? This is done through the method Object::setDataVariance(), setting it to STATIC or DYNAMIC. In your case, you should mark that object DYNAMIC in order to prevent OSG accesing it while you are modifying the mesh. Not exactly, just setting a node as DYNAMIC doesn't mean the app can safely alter a node at any time. See the OSG QuickStartGuide. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Modifying scenegraph and update
HI Martin, On Fri, Mar 5, 2010 at 4:25 PM, Martin Beckett m...@mgbeckett.com wrote: Thanks - I think I am misunderstanding the threading in OSG. In the gui I though frame() was called at 60fps, eg with a model rotating in the view. If I have a gui thread (say a non-modal dialog) that modifies the scene then I need to make sure that I don't have an invalid drawable/vertex array combination at any point. In my own code I was used to having a semaphore that prevented a repaint while the data was being modified - but didn't see anything like that in OSG You have to either pass a custom operation to the viewer to run at each frame to do the update, or a callback to make sure the the operation gets called at the appropriate time for the viewer, or to hold back the viewer.frame() till after you've made your changes. Since you control when frame is called it should be straight forward if you want to add a high level sync. Robert. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
