Le 30/04/2017 à 17:06, William F Pokorny a écrit :
> On 04/29/2017 08:05 PM, Jörg "Yadgar" Bleimann wrote:
>> Hi(gh)!
>>
>> I started to model the building blocks of a Swiss-made marble lane
>> system... when I came to an elongated block with a serpentine-shaped
>> marble track on top, I chose to use a cubic sphere to create the
>> hollow... but it resulted in heavy artifacts (object on the extreme
>> right of the scene attached). I tried various tolerance values - but
>> nothing removed those artifacts! Here is the code:
>>
> Thanks for posting code. I've opened a github issue for this:
> 
> https://github.com/POV-Ray/povray/issues/287
> 
> given it seems to render correctly in 3.6.1.
> 
> Bill P.
> 
Thanks for logging.

I tested with hg-povray and it is fine there (at least the tmp372.pov file)

Actually, it is also ok on my master head, but both stable and official
master have problem.

Which leads me to conclude: read the note about the patch of my master,
for sphere_sweep:
* sphere sweep: less noise under some angles
* sphere sweep: UV mapping
* sphere sweep: removed the preliminary workaround for FS#81 (not
effective, was adding noise)
* sphere sweep: added the suggested fix for FS#243 (negative uniform
scaling of untransformed object should have effect on radius as absolute
factor)


From what I would keep in the sphsweep.cpp, previously in
source/backend/shape (now spheresweep.cpp in source/core/shape ):
const DBL ZERO_TOLERANCE        = 1.0e-1;// less noise when near 1 than
near 0 [JG]

instead of

const DBL ZERO_TOLERANCE        = 1.0e-4;

Good luck.

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