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

[Julien Valentin]

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.
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 artifact such as
1)models out of volume tend to disappears (experienced in osgvolume ex)
2)In my own code it cause all sort of strange artifacts

to reproduce

Code:
osgvolume image --multipass --model cessna.osg



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
2/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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http://forum.openscenegraph.org/viewtopic.php?p=70407#70407