Hi Dirk, On 08.11.2011 21:26, Dirk Reiners wrote: > > Hi Christoph, > > On 11/08/2011 03:28 AM, "Christoph Fünfzig" wrote: >> Hi all, >> >> please consider the following case: >> I want to store a terrain as a geometry node >> (Positions and Normals as VBOs). >> Now I want to change small parts >> inside the Positions and Normals arrays only.. >> >> What change policy for VBOs is actually used? >> With the "changed" marking of arrays, >> would it make sense to subdivide the terrain (in a cluster)? >> Is it possible to change arrays without getting entries >> into the change list? >> >> Any comments are well appreciated! > > This is a case that OpenSG doesn't handle most efficiently right now. No > matter > how small the change, changes are only recorded on a Field level. Between > threads there is no cost associated with it, as only pointers are swapped, so > that's not a problem. But for cluster distribution small changes in large > arrays > can be a problem. We just haven't come across many situations where that > happens, most of the time the whole array is replaced. So with the current > system subdividing the terrain into smaller pieces would help with cluster > data > transfer. > > In theory you could extend the ChangeList to support partial transfers. The > problem is in how you detect them, how you combine multiple partial changes, > and > how you handle insertions/deletions in addition to just changes. It's a big > can > of worms to get it right... I would not like to allow arbitrary dynamic changes (insertions/deletions) of the data arrays. This can be quite difficult, as you sketched :) But is it possible to exclude certain data arrays from updates in the cluster and do updates on the render server side (with change data transfered in an app-specific protocol)?
This might also be interesting for streaming data to OpenGL (where the render data) is not in the SG? Might this be possible? Thanks again, Christoph -- NEU: FreePhone - 0ct/min Handyspartarif mit Geld-zurück-Garantie! Jetzt informieren: http://www.gmx.net/de/go/freephone ------------------------------------------------------------------------------ RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 _______________________________________________ Opensg-users mailing list Opensg-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/opensg-users
