Cousin Ricky <ric### [at] yahoocom> wrote:

> The warning about unexpected filter and transmit components indicates
> that the bug did manifest, but without altering `White`.  Did you create
> an image output?  Did you vstr() the expression `(White=1)`?

As far as I can remember (it was early and I was on my way out the door to
work):

I vstr()'d the expression White,

then instantiated the light source (copy/pasted kurtz le pirate's exact code) ,

then vstr()'d the expression White again.

Which is now even weirder, because if White got changed to include filter and
transmit, then why didn't it show up with vstr?  And why did it still have g&b
values of 1?

I'll check/post my actual code when I get home - but that won't be for another
5h.

- BE

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On 2026-02-25 17:09 (-4), Bald Eagle wrote:
> 
> I vstr()'d the expression White,
> 
> then instantiated the light source (copy/pasted kurtz le pirate's exact code) ,
> 
> then vstr()'d the expression White again.
> 
> Which is now even weirder, because if White got changed to include filter and
> transmit, then why didn't it show up with vstr?  And why did it still have g&b
> values of 1?
> 
> I'll check/post my actual code when I get home - but that won't be for another
> 5h.

The value of `White` never changes.  It is the expression `(White=1)`
(which is a conditional in this context, not an assignment) that you
should vstr().

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Cousin Ricky <ric### [at] yahoocom> wrote:

> The value of `White` never changes.  It is the expression `(White=1)`
> (which is a conditional in this context, not an assignment) that you
> should vstr().

Ah, yes.  Very interesting.

So <1, 1, 1> gets promoted to rgbft <1, 1, 1, 0, 0>,
and 1 gets promoted to <1, 0, 0, 0, 0>

and then comparing element by element ones gets

<1, 1, 1, 0, 0>
<1, 0, 0, 0, 0>
---------------
<1, 0, 0, 1, 1>


Totally logical, yet totally unexpected!

- BE

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On 25/02/2026 12:45, Bald Eagle wrote:
> I'm thinking that the red must be coming from something else.
> Post the whole scene, a link, or at least more to work from?

the scene :

#version 3.8;

#include "colors"

global_settings {
   assumed_gamma 1.0
   max_trace_level 5
   }
#default {
   finish {
     ambient 0.00
     emission 0.40
     diffuse 0.60
     }
   }

camera {
   location <40,20,22>
   up y
   right x*image_width/image_height
   look_at <0, a*0.60, 0>
   angle 36
   }

light_source {
   <290, 384, 1350>
   color White=1
   }

plane {
   y,0
   pigment { White }
   }

#declare a = 4;
box {
   <-a, 0, -a>, <+a, 2*a, +a>
   pigment { White }
   }


With the warning :
Parse Warning: Expected pure RGB color expression, unexpected filter and 
transmit components will have no effect.






-- 
kurtz le pirate
compagnie de la banquise

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