Marcus Barnes (marcus++at++multigen.com)
Wed, 14 Aug 1996 11:31:57 -0700
Performer 2.0 can do depth sorting in the CULL process, but it may not be
active by default (for opaque pfLayer's):
""
pfChannel(3pf) IRIS Performer 2.0 libpf C Reference Pages pfChannel(3pf)
The default sorting order for the PFSORT_OPAQUE_BIN bin is by pfGeoState
only and the default sorting order for the PFSORT_TRANSP_BIN bin is
PFSORT_BACK_TO_FRONT.
""
In any case, I've seen incorrect rendering of pfLayer geometry when some of the
decals and/or base layers have transparency, regardless of pfLayerMode. Their
respective visual priority is not handled correctly when viewed from opposite
sides.
[munch]
> Now, to render this ensemble using stencil-planes, the following
> approach does the job without error:
>
> a. enable "set stencil based on depth-compare pass/fail" mode
>
> b. render the base layer (#1)
>
> [note that at this point all of the pixels (subpixels on re/ir) in
> the area covered by #1 have a stencil bit that means: 1==visible,
> 0==invisible]
What is the behavior of this test if the base layer is partially transparent
but a decal layer is opaque? I wonder if it will render correctly according to
step (e) below? I assume that the stencil bit is set to 1 if the pixel is
updated at all.
> c. disable depth comparisons.
>
> d. disable stencil updates.
>
> e. enable "only draw where stencil == 1" mode.
[munch]
Regards.
--
____ ___ ____ _ Marcus Barnes, Member Technical Staff
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