Hello Frank,
You should try to create the 52 models cache outside the rendering tree (in a
separate list or a distinct tree detached from the camera). Even if the
visibility is turned off, I think the rendering visitors (update, cull, etc.)
are still browsing the whole tree. Also, don't forget that if you full your RAM
with all the cached models, you'll have to use virtual memory on the hard drive
which is much less efficient.
As for the threading model, I don't think this should affect performance much
if you have only one display window. If you have multiple rendering context,
it's very important to use multithreading if you wand reasonable performance.
You can change the threading model through the
osgViewer::Viewer::setThreadingModel() method.
Hope this helps!
Frederic Drolet, M. Sc.
Computing Solutions and Experimentations | Solutions informatiques et
expérimentations
Systems of Systems | Systèmes de systèmes
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From: osg-users-boun...@lists.openscenegraph.org
[mailto:osg-users-boun...@lists.openscenegraph.org] On Behalf Of Philip Lowman
Sent: November-10-09 12:52 PM
To: osg-users@lists.openscenegraph.org
Subject: Re: [osg-users] Would someone be willing to help me diagnose
aperformance issue?
Slowly minimize the differences between the slow machine and the fast machine
until the problem goes away. When it does, you have isolated the problem.
Also bear in mind it could be the machine itself (hardware, drivers, etc.)
On Nov 10, 2009 12:42 PM, Frank Sullivan knarf.navil...@gmail.com
wrote:
Hello,
I have two applications, both of which are displaying basically the
same scene. One application runs at 230+ fps while the other runs at about 45
fps. I'm trying to figure out what is causing this performance difference.
Using high-precision timers, I've been able to determine that the difference
occurs somewhere in the rendering of the scene graph, but I'm not 100% sure
where. I have a couple of ideas, but each will take some amount of time to
investigate, and so I was hoping someone might be able to lead me towards the
most-correct answer.
The first idea I had concerns differences in how the scene graphs are
structured in each application. The quick app works simply by loading the three
models that it needs (from FLT files, so these 'models' are in fact complex
sub-graphs) and attaches them to the root node, and sets that root node as the
scene data.
The slow app loads every model that could possibly ever be used (52 in
all, and again each 'model' could actually be a complex sub-graph). These 52
nodes are then attached to the root, and their visibility is turned off by
setting their node mask to 0. Then, if the user of the application wants to see
a model, the app will copy the node (and all of it's children) and then add
this copy to the scene root group, with the visibility turned on. This way, if
the user of the app wants to populate the scene with many instances of the same
model, they can do so, because each time they do it, a separate copy of the
node is made.
I realize that there are a lot of things that can be done to make the
slow app more memory-efficient. For instance, it could use lazy loading to load
a model only when it is needed (although this may cause a noticeable delay, but
that would probably be fine). And if the user wants to see several instances of
this model, this could be accomplished without copying the model's entire
subgraph. Instead, we could simply create a new matrix transform, and add THAT
to the root, and add the model's node as a child of this new matrix transform
(at which point, the model's node will have more than one Matrix Transform
parent).
However, these issues seem to pertain more towards memory efficiency
than rendering efficiency, so I'm not sure if this is going to solve my
immediate problem (although it is almost certainly something I will implement
later on).
Related to this, I was wondering if anyone had an explanation as to
what the Camera / View statistics referred to. I read the Quick Start Guide,
and it had excellent information about the Event/Update/Cull/Draw/GPU chart at
the top of the statistics screen, but I'm not exactly sure what the statistics
in the Camera / View windows refer to. For instance, does the Vertices stat
refer to the total number of vertices in all of the drawables, whether those
drawables are visible or not? The reason I ask is that, in terms of these
statistics, both the Quick App and the Slow App have nearly-identical numbers
