On Tue, Jul 6, 2010 at 11:14 PM, Cory Riddell <c...@codeware.com> wrote:
> Robert,
>
> Thanks for the quick reply.
>
> If I understand the NodeMask and CullMask, these would cull entire
> nodes, not individual osg::Drawable instances, correct?
>
Yes, but you can store one Drawable per Geode node, or perhaps group of
these Drawables that can be turned off into a single Geode.
>
> For example, I have geode's that contain a text label as one of their
> drawables. I thought about using a switch node to toggle the text on and
> off, but that seemed a bit heavy compared to a callback. With my draw
> callback, I can easily turn labels on or off for the entire graph. The
> penalty is that those drawables cannot use display lists.
>
> That could be a stiff penalty. Using a node mask also saves OSG work in the
cull and draw phases of the rendering loop.
Tim
> Cory
>
> On 7/6/2010 3:16 PM, Robert Osfield wrote:
> > Hi Cory,
> >
> > This is expected behaviour as the draw callback is nested within the
> > code that sets up display lists, so once the display list is created
> > it'll not call the callback again. If you disable the use of display
> > lists via drawable->setUseDisplayLists(false); then your callback will
> > be called on every frame.
> >
> > Another approach you could take to switching on/off various subgraphs
> > is to use a combination of NodeMask and CullMask. Have a look at the
> > osgstereoimage example for inspiration on this approach.
> >
> > Robert.
> >
> > On Tue, Jul 6, 2010 at 8:19 PM, Cory Riddell <c...@codeware.com> wrote:
> >
> >> I have a very simple draw callback defined that uses a bool to decide if
> >> the drawable should be drawn. The body of the callback's
> >> drawImplementation() looks like:
> >>
> >> if (m_enable)
> >> {
> >> drawable->drawImplementation(renderInfo);
> >> }
> >>
> >> I have drawables scattered all over my scene that use the same instance
> >> of this callback. By doing this, I'm able to toggle all of those
> >> drawables on or off by setting a single bool.
> >>
> >> This only seems to work though if the drawable has display lists
> >> disabled. My code to set the callback looks like:
> >>
> >> drawable->setUseDisplayList(false);
> >> // callback is my shared callback instance
> >> drawable->setDrawCallback(callback);
> >>
> >> Is this expected behaviour? If I understand this correctly, to use
> >> display lists, I would have to tell each drawable to recompile
> >> (dirtyDisplayList()) whenever I toggle my m_enable bool. Since the whole
> >> point of my shared draw callback is to avoid traversing my graph, doing
> >> so would defeat the purpose of my callback. So, do I understand this
> >> correctly?
> >>
> >> It looks like display lists can prevent a draw callback from being
> >> called. Is that right?
> >>
> >> Cory
> >>
> >>
> >>
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> >>
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> >>
> >>
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