Gordon Tomlinson wrote:
Robert is saying you should create your scene graph such that it replicates
a quad tree and separate the billboards in to geo-spatially partitioned
groups
Wouldn't the SPATIALISE_GROUPS option of the Optimizer class do this
automatically for him?
Paul
See http://www.vis-sim.com/imgdp/dbpart1.jpg, your tree is like the last one
'Root B' which is a very bad tree for a scene graph
The middle diagram shows a slightly better partioned tree ( although not a
quad its better than 'B')
as you know what a quad tree is then you should be able to create a much
more balanced tree
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Michele
Bosi
Sent: Friday, May 23, 2008 11:27 AM
To: OpenSceneGraph Users
Subject: Re: [osg-users] Small object frustum culling
On Fri, May 23, 2008 at 5:06 PM, Robert Osfield <[EMAIL PROTECTED]>
wrote:
Hi Michele,
On Fri, May 23, 2008 at 3:58 PM, Michele Bosi <[EMAIL PROTECTED]>
wrote:
Thank you Robert,
v-sync is off, I get around 90-100 FPS, when enabled OSG stats I get
3.4 for "cull" and 6.4 for "draw", also in this case the frame rate
basically does not change but floats around the same range 90-100.
Since the performances are already very good I wont dig more into the
"problem", which might not be a "problem" but rather a lack of
understanding of what's going on.
Another thing: I instance a single Geometry (my quad billboard) then
add it 4000 times to a Billboard node. I looked in the archives for
"quadtree" but coulnd't find any info. How can I use the quadtrees
you mentioned with OSG? Did you mean quadtrees to speedup frustum
culling or a particular parent/child layout for OSG nodes?
I'm afraid I can't teach you about general real-time graphics work I
have enough on my plate.
Thank you Robert, I know you are swamped of work and deliver for free a
great service to the list, but I am afraid you don't need to teach me
anything about quadtrees, I regularly work with quadtrees and octrees and
implemented several of them.
There are lots of books and online resources on items like quad trees.
Lots in the archives too.
I looked in the archives through this web page:
http://lists.openscenegraph.org/pipermail/osg-users-openscenegraph.org/
and there are exactly 0 results for "quadtree" and "quad-tree".
My question was very clear, and it has to do a lot with OSG and a few with
quadtrees but probably it was a misunderstanding.
In your mail you said: "Also with your scene graph, make sure you build a
quad tree to store all those billboards, and avoid large flat node contains
lots of children/drawables".
Did you mean, "OSG has a quadtree class somewhere, use it" or "implement
your own quadtree scene graph management, integrate it with OSG culling
mechanics, and put your billboards in it"?
Michele
Robert.
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