[osg-users] design issues

[Trajce Nikolov NICK]

Hi Robert,

I am very thankful for every hint, really. These hints are really valuable
for optimization. And I found the issue, it was pre/post multiply order of
the matrices. I was to avoid the calculus from the nodepath and use the
ModelView matrix already available in the CullVisitor. Here is the snippet
for someone who might face the same issue:

osg::Matrixd inverseViewMatrix = getCurrentCamera()->getInverseViewMatrix();
osg::Matrixd modelViewMatrix = (*getModelViewMatrix());
osg::Matrixd worldMatrix = osg::computeLocalToWorld(getNodePath());
osg::Matrixd worldMatrix2 = modelViewMatrix * inverseViewMatrix;

worldMatrix is equal to worldMatrix2 .. It was really the order of the
matrices. I was under impression it is the same as in GLSL

Thanks a bunch again!

Cheers,
Nick

On Thu, Nov 3, 2016 at 2:59 PM, Robert Osfield <robert.osfield at gmail.com>
wrote:

> I don't have time to dive deeply in user projects, I can do quick
> scans of email and provide quick replies where possible.  In terms of
> optimization I'd say avoiding the inverse matrix might be useful.
> Using the Matrix.postMultTrans/preMultTrans would also be another
> optimization step you could use.  The use of the UserValue looks like
> it won't be thread safe or even safe n the presence of multiple cull
> traversals.
>
> On 3 November 2016 at 11:40, Trajce Nikolov NICK
> <trajce.nikolov.nick at gmail.com> wrote:
> > Thanks Robert,
> >
> > I am aware of it, it is already used in my second snippet. Here it is:
> (is
> > it done properly?)
> >
> > void MyCullVisitor::apply(osg::LightSource& node)
> > {
> >
> >     osg::Matrixd inverseViewMatrix =
> > osg::Matrixd::inverse(getCurrentCamera()->getViewMatrix());
> >     osg::Matrixd worldMatrix = inverseViewMatrix *
> (*getModelViewMatrix());
> >
> >     osg::Vec3d pos(node.getLight()->getPosition().x(),
> > node.getLight()->getPosition().y(), node.getLight()->getPosition().z());
> >     worldMatrix = osg::Matrixd::translate(pos) * worldMatrix;
> >
> >     node.setUserValue("WorldMatrix", worldMatrix);
> >     if (node.getLight()->getLightNum() == 0)
> >     {
> >         osgUtil::CullVisitor::apply(node);
> >     }
> > }
> >
> >
> > On Thu, Nov 3, 2016 at 9:14 AM, Robert Osfield <robert.osfield at gmail.com
> >
> > wrote:
> >>
> >> Hi Nick,
> >>
> >> The osgUtil::CullVisitor has the maintains a stack of ModelViewMatrix
> >> that it accumulates through the the scene graph traversal, you should
> >> just need to get the top of this stack using
> >> cullVisitor->getModelViewMatrix().
> >>
> >> Robert.
> >>
> >> On 2 November 2016 at 22:25, Trajce Nikolov NICK
> >> <trajce.nikolov.nick at gmail.com> wrote:
> >> > Hi Community,
> >> >
> >> > I am trying to optimize the rendering. Getting huge update numbers.
> >> >
> >> > The story is this:
> >> > My scene has huge number of lights, some are static (streetlights)
> some
> >> > dynamic (a car). The lighting engine needs the World matrix of a
> >> > LightSource
> >> > and the ViewMatrix (which is the same as the World inverse just with
> >> > some
> >> > extra rotation). In my code after the update before the rendering
> >> > traversal
> >> > I am updating these matrices each frame and I am about to place this
> >> > code in
> >> > my custom CullVisitor (which traverse the scene anyway but only the
> >> > active
> >> > children).
> >> >
> >> > Here is my approach at the moment: list of light entities and here is
> >> > how I
> >> > am computing these:
> >> > http://pastebin.com/0A64sc7Y
> >> > Simply getting the NodePath and computing the world matrix from this
> >> > node
> >> > path. This seams to be costly
> >> >
> >> > I am after wiser optimization, to place this in my CullVistor: Here is
> >> > the
> >> > snippet:
> >> > http://pastebin.com/6dQnih8N
> >> >
> >> > These snippets are simple and I would like to ask if this is more
> proper
> >> > way, which it seams to me since I will gain more performance by
> updating
> >> > only the culled and active nodes. Also the math in the cull visitor.
> >> >
> >> > Thanks a lot for any hints, ideas. As always :-)
> >> >
> >> > Cheers,
> >> > Nick
> >> >
> >> > --
> >> > trajce nikolov nick
> >> >
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> >
> >
> > --
> > trajce nikolov nick
> >
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-- 
trajce nikolov nick
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