POV-Ray : Newsgroups : povray.pov4.discussion.general : Suggest v4.0 enable enhanced onion pattern. (yuqk R17 v0.6.11.0) : Suggest v4.0 enable enhanced onion pattern. (yuqk R17 v0.6.11.0) Server Time
10 Dec 2024 06:36:10 EST (-0500)
  Suggest v4.0 enable enhanced onion pattern. (yuqk R17 v0.6.11.0)  
From: William F Pokorny
Date: 15 Nov 2024 21:43:47
Message: <673806e3@news.povray.org>
Adding 'ip_form', 'ip_offset' and 'ip_raw_return' as options for the for 
the scalar value 'onion' pattern. When no options are used the behavior 
is unchanged.

The heart of the onion pattern is a distance from origin / center 
function wrapped in an fmod(value,1) call. The fmod() call itself 
creates a slight inconsistency due the general value modifier code using 
a version too. One which has historically and, though revised in yuqk, 
still skirts to 1+'numerical epsilon' in the fmod() call so '1' doesn't 
disappear from the 0 to 1 value range returned.

Enabling 'ip_raw_return on' suppresses the internal fmod() call making 
behavior more consistent with other patterns near the 1.0 multiples, 
snapping back to 0.0 values - 99.99% of the time it will look the same.

The three internal pattern (ip_) functions together allow the internal 
distance function to be used more generally and flexibly should folks 
want to do it.

See attached images. The upper left being the traditional onion 
translated +1 in z applied to a plane.

Bill P.


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onionrewrtstory.jpg


 

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