[osg-users] osgvolume multipass (hybrid geometric/volumic) bug...?

Julien Valentin julienvalentin51 at gmail.com
Sun Mar 5 15:40:42 PST 2017

I...have achieve something...
I removed line 394 in VolumeScene.cpp


and it works for me
but I can't tell if it's good.... A few doc on the underlying osgvolume design would be cool...

mp3butcher wrote:
> Hi Robert et al
> It's been a while I use a customized osgVolume::MultipassTechnique and experienced a bug I think was coming from my code but in fact it affect osgvolume application too.
> to reproduce
> Code:
> osgvolume image --multipass --model cessna.osg
> It seams there a bug in texgen (or somerhing like that) when writing back Pre rendered scene FB  to the main FB.. 
> It lead to artifacts when rotating the view such as
> 1)models out of volume tend to disappears (experienced in osgvolume ex  rotating the view-when cessna comes out of the hull 2D projection-)
> 2)models duplication (one is deformed and shouldn't be there)
> I would like to debug but would like to be sure how it work,
> I tend to understand the following, stop me if I'm wrong:
> 1/VolumeScene children (except tiles) is rendered as in depth and color textures in prerender and copy back to main FBO
> 2/Tiles Frontface then backface Hull are rendered to determine per pixels ray lengths and then per pixel numiterations ( so rays can be casted in BFHull pass)
> It's been a while I haven't dive in there. Can you tellme if I'm wrong and give me directions of what could possibly go wrong in the current MultipassTechnique...
> Thank you!
> Cheers,
> Julien

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