POV-Ray : Newsgroups : povray.binaries.images : Alum : Re: Alum Server Time
26 Sep 2022 08:43:17 EDT (-0400)
  Re: Alum  
From: Alain Martel
Date: 20 Sep 2021 09:31:25
Message: <61488d2d$1@news.povray.org>


> /*
> 
> HKL-cubic-alaun.pov
> 2021 Samuel B.
> 
> Suggested command line options:
>   +fn +f +a0.3 +am2 +r1
> 
> If outputting to luminous bloom:
>   +fh +f +a0.3 +am2 +r1
> 
> */
> 




generate PNG images by default.
Those two switches are default values since version 3.7.
+a0.3 is also the default when antialiasing is used.
The default of +r3 gives you better results.


> // crystal
> #if(1)
>   intersection{
> 
>    #for(I, 0, 49)
>     plane{
>      <FaceData[I][0], FaceData[I][1], FaceData[I][2]>, FaceData[I][3]
>     }
>    #end
> 
>    // I guessed the proper color :/
>    pigment{rgb <.85, .7, 1> filter 1}
For a crystal, this should be :
pigment{rgbt 1}
The colour don't come from the surface but from the substance itself.

> 
>    finish{reflection{0, 1 fresnel} conserve_energy}
> 
>    normal{granite .03 scale .001}
> 
>    interior{
This is where the colour of the crystal should be.
Starting settings :

	fade_color rgb <.85, .7, 1>//desired colour
	fade_power 1001 //how the path length affect the colour
	fade_distance 0.5 //base distance to be used for the fading

Adjust fade_distance to change the intensity of the colour of the crystal.

>     // alum ior from classicgems.net
>     ior 1.453
>     media{absorption .3}
You may also use a colour here.
As a starter, you may try :
{absorbtion rgb<0.15, 0.3, 0>}

Use the complement of your colour. That's 1 minus the desired colour.

>     // an unrealistic dispersion value
>     dispersion 1.075 dispersion_samples 7
>    }
> 
>    hollow
> 
>    rotate -y*43
>   }
> #end
>


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