POV-Ray : Newsgroups : povray.advanced-users : Extracting information from an existing color_map : Re: Extracting information from an existing color_map Server Time
2 Oct 2023 20:25:39 EDT (-0400)
  Re: Extracting information from an existing color_map  
From: William F Pokorny
Date: 18 Feb 2023 13:11:54
Message: <63f114ea$1@news.povray.org>
On 2/18/23 09:01, Bald Eagle wrote:
>> (a) As you know, the *_map mechanism in POV-Ray itself has long
>> supported  key/index values well outside the [0-1] range,

> By "supported", I'm assuming that you mean "doesn't crash".  or "Ignores
> out-of-range index values" and "wraps out of range key values back into the 0-1
> range".

Users of POV-Ray proper see the wrapping back into the 0-1 range 
behavior(a). This however is due the current pattern code which always 
wraps to a [0-1] repeating ramp_wave(a).

The *_map mechanism, itself, has long supported more - and this what I 
meant. We today cannot get values outside the [0-1] range to it(b) as 
raw, function return values!

Bill P.

(a) Lying a little as there is too some unfortunate one sided clamping 
code code sitting between functions and the pattern mechanism. Plus 
stepping point/value issues.

(b) The povr branch fixed (a) and is has the new waveform modifier, 
raw_wave. With it you can set up say -10 to + 10 *_maps - and make use 
of them. Related, I changed povr's inbuilt aoi pattern to allow return 
the full range of possible perturbed normals (-1 to 1) so users can 
visualize any normal inversion issues due too large bump_size settings.

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