Ooops sorry, there is a game http://www.fringe-online.com/ which makes full use
of collision detection (anyone can download the install). The test I am
running has 10 ships (5 red, 5 blue) that are all shooting at each other. I
guess what make these numbers special to me is that for every aspect of the
game, this code is the most frequent called, and by a significant amount.
Therefore, I'm going to look for any optimization opportunities (such as the
KDTree) to help.
The actual data comes from using the Amd Code Analyzer, while running the game.
James Killian
----- Original Message -----
From: Adrian Egli OpenSceneGraph (3D)
To: OpenSceneGraph Users
Sent: Thursday, July 17, 2008 2:27 AM
Subject: Re: [osg-users] KdTree support now checked in
Sorry,
i don't really understand where the bench come from. what did you messured,
linesegement intersection visitor?
2008/7/17 James Killian <[EMAIL PROTECTED]>:
I've got some numbers that are interesting:
In a build before KDTree.. Matrixd::mult was the most used method:
1367 Matrixd::Mult
1080 Matrixd::makeidentity
982 Group Traverse
With KDTree on here is how the numbers stand:
1305 Group::Traverse
1228 Matrix::mult
990 Compute Bound
776 Transform::Compute Bound
728 MatricsD::Make Identity
So we can see how the KDTree has brought down the number of Matrixd::Mults,
and so now Group Traverse can do more iterations.
James Killian
----- Original Message ----- From: "Robert Osfield" <[EMAIL PROTECTED]>
To: "OpenSceneGraph Users" <osg-users@lists.openscenegraph.org>
Sent: Saturday, July 12, 2008 10:46 AM
Subject: Re: [osg-users] KdTree support now checked in
Hi Adrian,
It's great to hear you getting better performance. How much is down
to more efficient intersections vs other changes to the OSG I cannot
say - you'd need to profile the relative costs of intersections/cull
and draw traversals etc.
KdTree are only used in intersections, so it doesn't change the cull
and draw traversals at all. It's not something that is likely to help
much anyway, as the OpenGL pipeline is geared up to handling a
moderate number of relatively large sets of geometry, and rarely is
the actual geometry a bottleneck so it doesn't pay to just a do fine
grained view frustum culling. Intersections a completely different
matter - ray intersection strongly favour fine grained
representations, hence why KdTree work so well.
Robert.
On Sat, Jul 12, 2008 at 4:41 PM, Adrian Egli OpenSceneGraph (3D)
<[EMAIL PROTECTED]> wrote:
Hi Robert,
i tested the whole afternoon with a really big terrain database (city of
cannes). i rebuild our internet based visualisation plugin with latest
openscenegraph (SVN of this morning) and the performance with
the kdTree datastructure enabled is much better than with elder OSG
version.
i don't yet understand why the performance is much faster, of course the
new
database pager concept could be responsable for the behaviour but i don't
think so. now the frame rate is really constant, no longer view dependent
for our motion model, also for the terrain manipulator. each of this
motion
model are using intersection visitor, may this was the reason why the
frame
rate was never constant, was view angle dependant. one pixel changed and
the
frame could dorp down or vise versa. but know the frame rate is nearly
constant, for this huge database. of course still view dependant, but
little
change doesn't no longer change the frame rate (60/20) between small
changes, this isn't question of culling,... i guess this was the
intersection test, if we passed through a huge object, the fps drops down.
this is greate.
next question. do you use the KDTree to cull objects against the frustum.
big objects (Triangles could better culled) if we can intersect easely a
plane against the kdtree.
/adrian
2008/7/12 Robert Osfield <[EMAIL PROTECTED]>:
Hi J-S,
On Sat, Jul 12, 2008 at 1:09 AM, Jean-Sébastien Guay
<[EMAIL PROTECTED]> wrote:
> I think I may be able to help a bit regarding the higher-level setup
> and
> bookkeeping changes needed to speed things up on that regard. One
thing
> I
> noticed before is that creating a new Intersector and
> IntersectionVisitor
> each time is costly, and instead keeping static or cached instances
and
> using the reset() and setStart()/setEnd() methods is faster. There may
> be
> some other similar things that can be done too, we'll see what I can
> dig
> up.
It's interesting how different bottlenecks pop up, in this case
creating objects on the heap is clearly showing itself as a bottleneck
whereas the old brute force intersection code was so slow that this
wasn't a significant factor.
Caching visitors and intersectors can certainly help, although one
does need to be careful about threading issues with doing this, as the
IntersectionVisitor and Intersectors aren't thread safe, so you'd need
a cached instance per thread.
Optimization could possibly be done with the data structure used to
store the intersection results, this would unfortunately break the API
compatibility. Changing that Intersector's are cloned might also help
performance when dealing with scene graphs have transform - the clone
is required to move the intersector into the local coordinate system
of transforms subgraph.
There other things one can do like grouping intersectors, or using
intersection coherency.
Robert.
_______________________________________________
osg-users mailing list
osg-users@lists.openscenegraph.org
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
--
********************************************
Adrian Egli
_______________________________________________
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
_______________________________________________
osg-users mailing list
osg-users@lists.openscenegraph.org
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
--
********************************************
Adrian Egli
------------------------------------------------------------------------------
_______________________________________________
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
