Hi,
I'm woundering - is it phisicaly ok that light (interior - fade_power) 
fades to black ? imho light should fade to some color.
But using fade_color same as pigment color results in no fading at all.

I.e. think about human's skin.
I.e. we have 3 small splinter's inside humans finger (drastic example ;)
All are white.

The object that is at 'depth' of 0.1 mm will have normal white color.
This at depth 2 mm will have ie 50% it's color, and 50% of skinns color, so 
it will be bright-"orange".
And this at dethp over 5 mm will be in fact invisible from outside.

How can I simulate this in POV ? Maybe little example (box=finger, 
sphere=splinter)

-- 
#macro g(U,V)(.4*abs(sin(9*sqrt(pow(x-U,2)+pow(y-V,2))))*pow(1-min(1,(sqrt(
pow(x-U,2)+pow(y-V,2))*.3)),2)+.9)#end#macro p(c)#if(c>1)#local l=mod(c,100
);g(2*div(l,10)-8,2*mod(l,10)-8)*p(div(c,100))#else 1#end#end light_source{
y 2}sphere{z*20 9pigment{function{p(26252423)*p(36455644)*p(66656463)}}}//M

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"Rafal 'Raf256' Maj" <raf### [at] raf256com> wrote in
news:Xns### [at] 204213191226 

[...]

sorry, forgot to add this - I don't want to use media - it's slow and not 
accurate. 

Imho scattering media with constant density will give proper effect, but - 
how about add way to calculate this very tryvial effect without using 
standart media - that is slow and innacurate ?

-- 
#macro g(U,V)(.4*abs(sin(9*sqrt(pow(x-U,2)+pow(y-V,2))))*pow(1-min(1,(sqrt(
pow(x-U,2)+pow(y-V,2))*.3)),2)+.9)#end#macro p(c)#if(c>1)#local l=mod(c,100
);g(2*div(l,10)-8,2*mod(l,10)-8)*p(div(c,100))#else 1#end#end light_source{
y 2}sphere{z*20 9pigment{function{p(26252423)*p(36455644)*p(66656463)}}}//M

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"Rafal 'Raf256' Maj" wrote:
> Hi,
> I'm woundering - is it phisicaly ok that light (interior - fade_power)
> fades to black ? imho light should fade to some color.
> But using fade_color same as pigment color results in no fading at all.
>
You need to give fade_color very low values to still get visible fading
for example rgb<0.1,0.2,0>. This is because rgb 0 is the default and rgb 1
doesn't give any fading so to get almost the same fading as with the default
only colored you have to use such low values.

Simon

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In article <Xns### [at] 204213191226>,
 "Rafal 'Raf256' Maj" <raf### [at] raf256com> wrote:

> I'm woundering - is it phisicaly ok that light (interior - fade_power) 
> fades to black ? imho light should fade to some color.

No, it should fade to black. As distance increases, it allows less and 
less light to pass through.


> But using fade_color same as pigment color results in no fading at all.

You are probably using too high of a color value or simply can't see the 
fading because of the pigment color. Make the pigment color "rgbf 1".


> I.e. think about human's skin.
> I.e. we have 3 small splinter's inside humans finger (drastic example ;)
> All are white.
> 
> The object that is at 'depth' of 0.1 mm will have normal white color.
> This at depth 2 mm will have ie 50% it's color, and 50% of skinns color, so 
> it will be bright-"orange".
> And this at dethp over 5 mm will be in fact invisible from outside.

Skin is a different case, it scatters quite a bit of light. Interior 
attenuation can not simulate this, you need scattering media.

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/

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In article <Xns### [at] 204213191226>,
 "Rafal 'Raf256' Maj" <raf### [at] raf256com> wrote:

> sorry, forgot to add this - I don't want to use media - it's slow and not 
> accurate. 

Actually, media is more accurate in most cases. And it usually isn't too 
slow to use.


> Imho scattering media with constant density will give proper effect, but - 
> how about add way to calculate this very tryvial effect without using 
> standart media - that is slow and innacurate ?

Absorbing media is the analog of attenuation, not scattering. And media 
is accurate, that's why it is slow.

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/

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