Re: Transparency
Angus Dorbie (dorbie++at++sgi.com)
Mon, 28 Dec 1998 20:09:45 -0800
Anda Singer wrote:
>
> I have a Performer application that works fine on ONYX but has strange
> behaviors on O2 regarding transparency.
>
> The sky earth is seen through the transparency even when it shouldn't
> because it has different geometry in between.
> I took some image snaps and the pictures can be seen at :
> http://www.cs.technion.ac.il/~anda/files/O2_transparency_bug.html
>
> I tried different sortings but it didn't help.
>
> Is that a known bug? How can I fix it?
>
> --
> Anda
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Anda Singher anda++at++cs.technion.ac.il
> tel: 04-8293905
> http://www.cs.technion.ac.il/~anda/
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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This is a sorting problem.
Your ONYX uses subpixel multisample masks when renedring
transparency and so doesn't have this problem. Your O2 has
a single depth and color sample per pixel so you need to
sort the transparency in the cull traversal so it's drawn
after opaque geometry.
Bitwise OR in the PFCULL_SORT flag in the setTravMode
PFTRAV_CULL traversal flag.
Cheers,Angus.
--
"Only the mediocre are always at their best." -- Jean Giraudoux
For advanced 3D graphics Performer + OpenGL based examples and tutors:
http://www.dorbie.com/
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on Mon Dec 28 1998 - 20:09:52 PST