Thanks for the post Reiche,
So, basically it works pretty much as the basic example at starterGuide,
only that SortLastWindow is used instead of the basic ClusterWindow and a
composer must be set. So, let me see if I understand correctly what is
happening behind the code you sent (the same at Tutorial28):
-> SortLastWindow will take care of sending each node to a different
rendering server, instead of sending everything to all servers
-> After each server has rendered it nodes, the scene fragments are composed
accordingly with the composer strategy.
-> What happens behind is that each node of geometry is a fieldContainer
itself, and so it has it own ChangeList for tracking any changes at each
different Thread. So, what really happens is that some how SortLastWindow
can send each ChangeList entries to a specific server instead of sending
every time for all servers.. Is that right?
Please correct me if I made any mistake and please post any complementary
explanation if possible ;)
Thank you very much
2007/5/14, Rieche, Marcus <[EMAIL PROTECTED]>:
Hi!
I forgot: For sort Last you need at least so many nodes in your scenegraph
as servers you want to use. More nodes can be better. More or less servers
not quite. That's something depending on the data.
I think working with fields is to deep in detail?!? You just have to make
multiple geo nodes instead of only one. SortLast distributes whole nodes to
the servers. So with only one node only one server would
really work.
Is this what you ment?
greetings
Marcus
*Von:* [EMAIL PROTECTED] [mailto:
[EMAIL PROTECTED] *Im Auftrag von *Pablo
Carneiro Elias
*Gesendet:* Montag, 14. Mai 2007 03:52
*An:* [email protected]
*Betreff:* Re: [Opensg-users] About OpenSG clustering
Hi Marcus and Rieche,
I´ve read many things about OpenSG clustering, Multi-Threading support,
Aspects, ChangeLists and stuff... Everything is quite simple to understand
since everything is very well planned and done. But I still have a question
about OpenSG clustering that you or someone may come to answer.
Here´s the issue:
I´ve found many things about how to build a simple clustering app using
OpenSG, there is many examples available including one at OpenSG starter
guide. But all these examples show only how to replicate the whole data to
all rendering nodes (servers), and in these cases each display is a single
display (each server renders to a independent display) .
But I couldn´t find how can I set my model to be split into pieces and
each of them sent to a different rendering server, so each server can render
a small part of the full model, and then the final image can be composed
using frame buffer information (for any detph composition it may be needed).
I want to know if there is any tutorial or example of how can I do this with
OpenSG. I think it is possible to be done by OpenSG because this article
I´ve read, writen by Marcus Roth himself (Multi-Threading and Clustering for
Scene Graph Systems), said it is possible:
"The described system supports this kind of distribution
as well. This can be done through smart
handling of the ChangeLists, splitting them and
sending only the parts that are necessary for every
specific cluster machine."
I know I can only split things at Field level of Field container... so I
would have to set my model to have the geometry split into many different
fields so it can be possible?...
I´m not totally sure if I can program it yet.... If anyone has any doc or
tutorial explaining that would be great.
Thanks
2007/5/13, Pablo Carneiro Elias < [EMAIL PROTECTED]>:
Thank you very much Marcus, it is of great help, it is a gold mine for me,
thanks!
2007/5/13, Rieche, Marcus <[EMAIL PROTECTED]>:
Hi!
Here is the thesis from M Roth. It wasn't linked on the page postet before
(the other documents need special access. Can't access them). But it is in
german.
You will find there much theory about the methods used in OpenSG.
Especially SortFirst, SortLast and how to communicate in a cluster. Don't
know which paper it was but there was a one with a short explanation in
english.
The field concept is explained in this paper.
http://www.lsi.usp.br/~mkzuffo/PSI5787/opensg/Reiners_Basics.pdf<http://www.lsi.usp.br/%7Emkzuffo/PSI5787/opensg/Reiners_Basics.pdf>
Okay most can be found with google scholar.
Greetings
Marcus Rieche
*Von:* [EMAIL PROTECTED] [mailto:
[EMAIL PROTECTED] *Im Auftrag von *Pablo
Carneiro Elias
*Gesendet:* Samstag, 12. Mai 2007 22:21
*An:* [email protected]
*Betreff:* Re: [Opensg-users] About OpenSG clustering
Hi Carsten, I thank you very much for the information. I´ll start studying
from these two classes (RemoteAspect and ChangeLlist) and I´ll probably have
many questions soon. Thanks!
[]´s Pablo.
2007/5/12, Carsten Neumann <[EMAIL PROTECTED]>:
Hello Pablo,
Pablo Carneiro Elias wrote:
> Hi Everyone. I need some support from anyone who deeply understand
OpenSG
> clustering algorithms and strategies.
hm, I'm not that deeply familiar with the cluster code, but I know how
it works in principle.
> Here´s the issue: I´m working on a big project together with my
university
> and we have a demand for real time simulations using a lot of
> geometry (about 1 or 2 million triangles at least) that changes all the
> time (due to the simulations) and should necessarily run on a cluster.
>
> Once we´re willing to use OpenSG as the scenegraph (among other things,
> also
> because of the clustering native support of OpenSG), my task is to
analyze
> the efficiency of the clustering algorithms and strategies of OpenSG. I
> need
> to study what happens behind the magic of OpenSG clustering (how the
> data is
> transfered, including protocol details, the strategy of data sharing -
> whether or not the whole geometry is sent every time even if just a
small
> part of it is changed)...
The basic unit for OpenSG to track changes is a Field. So if you modify
a single vertex or all of them does not matter, the whole field is
considered changed. Consequently if only parts of a large model change
these parts should be put into a Geometry core by themselves.
What OpenSG does to make clustering work is the same it does to get
multithread suppport: It records changes to fields and transmits those
changes over the wire (the RemoteAspect does this, see
Source/System/Cluster/Base/OSGRemoteAspect.{h,cpp}, changes are recorded
in the change list for the aspect, see
Source/System/FieldContainer/OSGChangeList.{h,cpp})
> I know the first thing I should do in order to get all this information
is
> to open OpenSG source code and to study it (I´m doing it by now), but
since
> my time is VERY short (the report must be ready in 3 days, and the task
was
> assigned to me yesterday), I need any document that can help me to
achieve
> my goal of analyzing things behind OpenSG clustering (hard code
details). I
> need any benchmark document or algorithm analysis document or anything.
Any
> help will be very welcome.
AFAIK Marcus Roth has written most of the cluster code and published a
number of papers on the topic (here is a list, but the documents can not
be downloaded from that site:
http://www.igd.fhg.de/~mroth/<http://www.igd.fhg.de/%7Emroth/>).
Sorry, I
don't have any download links to these.
> Thank you very much. I hope anyone can help me on anything (any
explanation
> about any detail of OpenSG clustering will be very welcome to).
I know it's not exactly what you were asking for, but I'll try to
regularly check my inbox over the weekend, so if you have any specific
questions, feel free to ask.
Good luck with your report,
Carsten
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