[osg-users] RFC: Positional state container in the render bin, was: clip planes

Mathias Fröhlich Mathias.Froehlich at gmx.net
Fri Sep 14 23:06:43 PDT 2007

Good morning Robert,

On Thursday 13 September 2007, Robert Osfield wrote:
> I'm just trawling through the morning inbox and a blurry headed so not
> in a zone able to contemplate complex stuff too deeply.  I will review
> your changes a latter date though.

> Was there much fallout from applying your changes?  Do things function
> w.r.t normal OSG usage and the type of usage you need?
Well it helps for reusing clip plane numbers for different parts of the 
scenegraph. You remember that we discussed that topic for flightgears 
instrument panels when you visited us in Tübingen.
Also I can imagine that being able to reuse light numbers is a good idea for 
some applications.

That will definitely help me implementing instrument panels for flightgear. 
With the current osg implementation, I will need to implement them as a 
custom drawable. With that patch I can make use of scenegraph elements for 
that. That will definitely be more generic than ...

As you can see in the changed clip node example, usage of clip nodes and light 
sources is the same than before. Just the scope where such a positional state 
is valid is then a render bin instead of a render stage.

To be honest, I do not really understand what you mean with fallout. So, I 
hope that this will answer your question.

An other possible solution to that 'reuse of clip plane numbers problem' would 
be to introduce some PositionalStateBin derived from the RenderBin and the 
Render Stage derived from the PositionalStateBin. Then we would need 
something to trigger the usage of a such a PositionalStateBin instead of a 
normal RenderBin in the rendering backend.



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