Hi,
On Wed, 2011-11-23 at 12:32 +0100, "Christoph Fünfzig" wrote:
> Hi Carsten,
>
> On 22.11.2011 18:44, Carsten Neumann wrote:
> > Hello Christoph,
> >
> > On 11/21/2011 11:27 AM, "Christoph Fünfzig" wrote:
> >> > I want to do
> >> > singleton->passiveWin[id]->render (singleton->action[id]);
> >> > in several threads on the same aspect.
> > hmm, may I ask why? That sounds like it would cause quite bad thrashing
> > on the driver/GPU side...
> >
>
> I have never looked into driver code ;) But it would cover the
> traversal/culling time of the scenegraph.
> It is mentioned here
> http://www.equalizergraphics.com/documentation/parallelOpenGLFAQ.html
> so would like to try it out among the other possibilities :)
on a stage level we already support what is described under 2. where
complete stages can have their OpenGL commands executed while the
main traversal continues to run in parallel.
> >> > In method RenderPartition::dropFunctor(DrawFunctor&, State*, Int32, bool)
> >> > which belongs to RenderAction, there is
> >> > "
> >> > DrawableStatsAttachment *st = DrawableStatsAttachment::get(actCore);
> >> >
> >> > if(st == NULL)
> >> > {
> >> > DrawableStatsAttachment::addTo(actCore);
> >> >
> >> > st = DrawableStatsAttachment::get(actCore);
> >> > }
> >> >
> >> > "
> >> > which looks not deadlock-free to me (as it adds an attachment to the
> >> > node),
> > correct, that is going to cause problems if run concurrently.
> >
>
> Sorry, I meant race condition, as one thread meets the test "st==NULL"
> first and proceeds to adding the attachment.
> A second might already see "st!=NULL" which is not yet correctly linked to
> the node.
>
> >> > Is there the possibility to move this out of the render traversal
> >> > into a preparation phase "add DrawableStatsAttachment"?
> > part of the problem is that scene traversal is somewhat expensive for
> > OpenSG and if new geometry is added it would need to get an attachment,
> > so it's not enough to just run this preparation pass once.
>
> Providing these attachments could be made the responsibility of the
> application code.
> Then there could be custom traversals to attach them outside the render loops.
The problem is that this element came in to support the occlusion
culling traversal so it is needed deep inside the rendering traversal
and not just something utilized by the application.
> But using several aspects might be an alternative ;)
At the moment, yes.
> >> > Or can StatsCollector be switched off completely?
> > By default the render action does not have a StatCollector; I changed
> > the code to only add the attachment and collect statistics if there is a
> > collector present (otherwise it's a waste of time anyway).
> > Incidentally this also fixes a bug where we were counting triangles twice.
> >
> >> > How are resources handled during traversal on different windows?
> > Sorry for being slow, but I don't quite get what you are asking for, can
> > you rephrase the question or give an example of what handling for which
> > resources you are interested in?
>
> If you have 2 windows/contexts and 2 render actions, the display lists are
> created and stored for each one, for example?
yes, all OpenGL objects are bound and maintained by the window, so for n
windows you will have n times the OpenGL resources allocated. Currently
we do not support sharing of contexts out of the box. The render action
will carry some traversal dependent OpenSG elements.
> Currently, I am not seeing anything. Perhaps I may send the debug log offline?
As there can be quite some reasons for not seeing anything that would
be helpful. A good starting point would be to use a OpenGL debugger and
see if the OpenGL command stream looks as expected.
> I will try to use several aspects.
> How is the max number of aspects set with OpenSG 2.0 ?
that part is gone. Aspects copies are allocated on the fly (sync) and
not while creating the initial container copy, so there is no need to
specify the maximum number of aspect in the beginning anymore.
The complex scenemanager contains a reference implementation for
parallel drawers on multiple aspects (DrawManager/Drawer) so it might
be a convenient reference. I'll have to check if I have the multiple
windows CSM Example committed.
kind regards
gerrit
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