POV-Ray : Newsgroups : povray.binaries.images : How does cylindrical warp work? : Re: How does cylindrical warp work? Server Time: 18 Jun 2019 06:40:11 GMT
  Re: How does cylindrical warp work?  
From: Cousin Ricky
Date: 4 May 2019 18:33:36
On 2019-05-04 12:49 AM (-4), Cousin Ricky wrote:
> OK, so it turns out I don't understand cylindrical warp after all.
> [snip]
> True to the docs, orientation z matches the default, not orientation y. 
> And somehow, orientation z corresponds to a cylinder with axis y.  I do 
> not understand why this is; and more importantly, I have no clue how to 
> get a cylindrical warp to match a cylinder of arbitrary orientation. How 
> does it work?
> Also, I am bemused by the cylinder illustration, which somehow works 
> with a vertical cylinder and orientation y, and I am befuddled the 
> spiral at the top; but since the example uses a non-default dist_exp 
> (whose explanation soars way above my head), I don't know if it's relevant.

I rendered some permutations of the example in the reference manual, and 
two things are clear.  Most obviously, I should leave dist_exp alone. 
The other is that all orientations work with a vertical cylinder. 
Extrapolating, it looks to me that the cylindrical warp always assumes a 
vertical structure, and that I should start with that assumption in 
defining the texture, then reorient it to match the object.

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