POV-Ray : Newsgroups : povray.general : colors map interpolation : Re: colors map interpolation Server Time
30 Nov 2022 04:54:55 EST (-0500)
  Re: colors map interpolation  
From: kurtz le pirate
Date: 21 Nov 2022 11:29:57
Message: <637ba785$1@news.povray.org>
On 20/11/2022 21:07, Bald Eagle wrote:
> "Bald Eagle" <cre### [at] netscapenet> wrote:
> 
>> Sure - I think you could take something like a gradient pigment pattern, apply
>> that color mapping to it, and then use that as a function.   Then you could pass
>> in a space coordinate with a vector component parallel to that gradient, and the
>> function would return the interpolated color vector as a result.
>> You would of course, have to write / generate 3 functions - one for the .r, .g,
>> and .b components.
> 
> 
> 
> Like this:
> ...


Waouh, impressive !!!

Based on your brilliant example, here is the macro :
// -------------------------------------------------------------------
#macro GetColor(thisColorMap, thisEntry)
 #local index = max(0.0, min(thisEntry, 1.0));

 #local Gradient = pigment { gradient x color_map { thisColorMap } }
 #local GradientFunction = function { pigment { Gradient } }

 #local R = GradientFunction (index, 0, 0).red;
 #local G = GradientFunction (index, 0, 0).green;
 #local B = GradientFunction (index, 0, 0).blue;

 rgb <R, G, B>
#end
// -------------------------------------------------------------------


And used like that :
sphere {
  <XX, 0, 0> 5
 pigment { GetColor(MyColorMap, XX/image_width)  }
 translate -x*image_width/2
 }



-- 
Kurtz le pirate
Compagnie de la Banquise


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