Every pixel is identical in the following scene:

// +A0.1 +R3
camera {
 location -z*5
 look_at 0
}
plane {
 -z,0
 pigment {
  rgbt <2,1,1,.5>
 }
}

yet, when rendered with AA and Output_Alpha=on, every pixel is supersampled
(check the stats, it says 9 samples/pixel).

According to "5.2.6.4  Anti-Aliasing Options" in the docs, a pixel is
supersampled if

abs(r1-r2) + abs(g1-g2) + abs(b1-b2) > threshold

(where r1 and r2, etc, are the colors of adjacent pixels.) It seems to me
that the logical extension of this, when outputting alpha, is:

abs(r1-r2) + abs(g1-g2) + abs(b1-b2) + abs(a1-a2) > threshold

where a1 and a2 are the levels of transparency of each pixel. But it seems
that the implementation here is that any partially transparent pixel is
supersampled. This could be horrible in a scene with something like
slow-rendering clouds when alpha output is on.

Version 3.5.beta.RC1, win98, pentium 3 (900mhz), 256MB.

- Slime
[ http://www.slimeland.com/ ]
[ http://www.slimeland.com/images/ ]

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In article <3cc0e539$1@news.povray.org> , "Slime" <noo### [at] hotmailcom> wrote:

> Every pixel is identical in the following scene:

Same as

* Slowdown using +a +am1 +ua (job000191)
  (Using +ua and antialiasing with method 1 causes abnormal slowdown.)

It will be fixed in the next beta.

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

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You probably meant Release Candidate #2, right? ;-)


Thorsten Froehlich wrote:

>
> It will be fixed in the next beta.
>
>     Thorsten
>

--
Tim Nikias
Homepage: http://www.digitaltwilight.de/no_lights/index.html
Email: Tim### [at] gmxde

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Thorsten Froehlich <tho### [at] trfde> wrote:
>> Every pixel is identical in the following scene:

> Same as

> * Slowdown using +a +am1 +ua (job000191)
>   (Using +ua and antialiasing with method 1 causes abnormal slowdown.)

  Ah! The great mystery solved!
  It had to have some rational explanation, and fortunately it has. :)

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

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> You probably meant Release Candidate #2, right? ;-)

That will be something like
" version 3.5.beta.RC2.icl.win32."
              ^^^^

It's still beta, but not a simple number anymore ;->

cukk

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