POV-Ray : Newsgroups : povray.bugreports : bump maps inverted in spherical warp : Re: bump maps inverted in spherical warp Server Time
25 Sep 2022 23:56:39 EDT (-0400)
  Re: bump maps inverted in spherical warp  
From: Bald Eagle
Date: 5 Aug 2021 21:05:00
Message: <web.610c8a76fbcfb68e1f9dae3025979125@news.povray.org>
William F Pokorny <ano### [at] anonymousorg> wrote:

> I think you've got it Bill. The behavior, though, looks inconsistent to
> me. Maybe if I think about it more, it's how it must be?

Well, there are so many ways to go about it.

> (a) - Not done any debugging to see if the 'pointless' warps / modifiers
> end up used.
> Aside 1: turbulence{} trips this parse error too.
> Aside 2: transforms can be pointless too and like turbulence and warp we
> 'sometimes' get PossibleError warnings for those though I'm not aware of
> any hard errors there.

Indeed.  However, I would imagine that one might code up something that just
loops through a bunch of things that these may or may not have any visible
effect on, and it's just a throwaway operation for those instances.

> Aside 3: With image based mapping, the usual approach would be to use
> the appropriate map type inside the bump_map{} block - here 'map_type 1'
> spherical - though the warp{spherical} modifier should work too.

Probably the best approach, I would imagine.   Tailor made for the purpose.

> Aside 3a: There is too 'uv_mapping' for spheres which can be used inside
> texture, pigment and normal blocks.

There is, though I still haven't figured out how to separate the the normal from
the uv mapped texture...  Someday...

> :-) Nothing if not lots of knobs,  buttons and switches!

No.  Kidding.
There are days when I am truly astounded that all of the bits of things the user
wants to do and demands of the parser and modifier hierarchy all more or less
work after processing billions of cycles of under-the-hood raytracing black

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