POV-Ray : Newsgroups : povray.bugreports : CLipka: Possible BUG Found!!! :-) : Re: CLipka: Possible BUG Found!!! :-) Server Time
2 May 2024 16:06:49 EDT (-0400)
  Re: CLipka: Possible BUG Found!!! :-)  
From: clipka
Date: 14 Feb 2016 15:28:37
Message: <56c0e375$1@news.povray.org>
Am 14.02.2016 um 21:01 schrieb Kenneth:

> As the 'depth' value in the macro increases, the radius of the entire
> height_field cylinder ALSO increases (but not the *length* of the cylinder)--
> you end up with a 'fatter' cylinder, which actually distorts the 3D image_map
> pattern. The pattern looks stretched-out horizontally. (You can see this by
> setting 'depth' to an extreme .99.)
> 
> IDEALLY, as 'depth' increases, the cylinder should stay at the same radius, with
> the image_map function simply 'eating into' it. But that's not what happens.

That wouldn't be ideal either, as it would /reduce/ the effective radius
of the entire height_field cylinder on average, creating the opposite
distorting effect.

The fact is that there is no ideal solution (because there is no telling
what the average height of your image_map function is), and whoever
implemented HF_Cylinder just picked this particular implementation for
other properties.

The primary reason may have been that a corresponding behaviour in
HF_Sphere makes it easy to use for modeling planets, with the nominal
radius specifying sea level and everything else being raised above it.

> I'm working on some SCALE equations to compensate for this, but it's...
> complicated. The first thing to do is to scale up the *length* of the cylinder,
> to get the embossed pattern to look undistorted again. Then the entire cylinder
> needs to be scaled *down*, to get it back to its original radius and length.
> 
> The tricky thing about this is that it all depends on the particular 'depth'
> value used.

Maybe the easiest way to approach this is to simply adjust the nominal
radius parameter as you change the depth parameter.


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