[osg-users] osgOcean in CompositeViewer with multiple views

Jean-Sébastien Guay jean-sebastien.guay at cm-labs.com
Sun Apr 17 13:47:44 PDT 2011

Hi Kim,

> Firstly thanks for the recent set of commits, much appreciated.

Yes, we've started a few more projects that will require a more recent 
osgOcean build than we'd been using up until now (specifically to be 
able to see through the surface when the camera is above the water), and 
so in starting to use the newer versions I fixed a few small issues. The 
larger one is still to be fixed though :-)

> Now onto your problem. I had a feeling that that there would be problems
> when using osgOcean with multiple views, largely because of the LOD
> system that it employs relying on the main camera.

You had mentioned that in the past, yes, but LOD is not that much of an 
issue to us since all cameras are normally pretty close together so any 
artifacts are not too visible. However wrong refractions are very 
visible :-)

> I've had a play with
> your composite viewer code and what I don't understand is why the
> reflection pass renders correctly in both views but not the refraction
> pass, they both use the same view matrix and despite the multiple render
> targets their implementations are the same.

I know, that's a mystery to me too.

> Ultimately I think the ViewData approach you suggested is sound, it
> sounds like the solution mentioned above and I'm pretty sure it's needed
> to get the post processing effects to work as well.

I think so too, and it's what the new osgShadow techniques do, so it 
would be reusing an existing "pattern" more or less.

I'm going to be on vacation until Wednesday of next week (and will stay 
clear of any technology during that time :-) ) but once I come back I'll 
start working on a solution in that vein. It'll be pretty important that 
I do this soon.

> But I would be keen
> to dig a bit deeper to figure out why reflections work but refractions
> don't as this sounds like a bug somewhere.

Let me know what you find out, I've looked into it a bit but haven't 
been able to find anything conclusive.

Thanks for your help,

Jean-Sebastien Guay    jean-sebastien.guay at cm-labs.com

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