Warp wrote:
> Jan Dvorak <jan### [at] centrumcz> wrote:
>> Hello,
>> when using +am2 (recursive antialiasing), are the corner samples shared 
>> between their respective pixels, that is, is +am2 as fast as +am1 or is 
>> it four times slower if no antialiasing takes place? Are the edge 
>> samples reused?
> 
>   I actually don't know the exact details of the antialiasing algorithm
> used, but I have the impression that no samples are shared between pixels
> in either method. This is because antialiasing can be jittered, and if
> that's the case, most samples wouldn't be at pixel edges and thus difficult
> to share. (I have to admit, though, that I can think of variations where
> samples can be jittered *and* shared between pixels. However, I don't know
> exactly what POV-Ray is doing.)

I don't see a problem with jittering a shared sample.  Samples can be 
assigned to a particular place in the pixel, and this assignment used to 
determine any sharing between pixels (or sub-pixels, since this is 
adaptive); when the sample is actually traced, it can be jittered at 
that time.

Regards,
John

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