POV-Ray : Newsgroups : povray.general : Is this a (known) bug? ? : Re: Is this a (known) bug? ? Server Time
1 Aug 2024 18:25:11 EDT (-0400)
  Re: Is this a (known) bug? ?  
From: Mike Williams
Date: 16 Jun 2005 12:41:39
Message: <vNN4MCA5uasCFw3l@econym.demon.co.uk>
Wasn't it Shay who wrote:
>// uncommenting last cylinder makes
>// other two "disappear"

It looks like some sort of vista buffer effect.

If you switch off vista buffers (-UV in the command line) then all the
cylinders reappear.

The default bounding threshold is 3. If you increase the bounding
threshold (+MB4 in the command line) to be greater than the number of
objects then all the cylinders reappear. Vista buffers can't happen
without bounding. That explains why introducing a third object provokes
the effect.

It seems that when POV calculates the vista buffers for the two
cylinders, it considers them to be out of sight, but when it tries to
render them without vista buffers, it considers them to be in sight.

The fact that the min_extent and max_extent of the cylinders is
calculated correctly, and the fact that the scene renders correctly with
bounding but without vistas, suggests to me that there's something odd
with the vista calculations.

-- 
Mike Williams
Gentleman of Leisure


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