In article <3c782d3c@news.povray.org>,
 "Rune" <run### [at] mobilixnetdk> wrote:

> It is clipped before AA and there's a good reason.
> 
> Suppose you have a really bright sphere (the sun). All pixels that hit the
> sun would be completely white no matter if the sun occupies a small or big
> amount of the pixel, simply because the high brightness would dominate in
> the average. The result would be that very bright objects would not look
> antialiased at all no matter how high quality AA settings you used.

Well, this explains why I never succeeded in getting stars to survive AA 
by increasing their brightness...that was the exact effect I expected 
and wanted. I can manually soften the sun's outline (media, or a dimmer 
sphere visible just around its edges), eliminating the problem there, 
but there doesn't seem to be any way to compensate for small 
(sub-pixel), very bright objects getting obliterated by the antialiasing.
Maybe a smarter algorithm would be possible...if there are other 
high-brightness pixels nearby, you are at the edge of a bright object, 
so clip and supersample, otherwise supersample then clip.

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/

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