[before light_source]
White = <1.000, 1.000, 1.000, 0.000, 0.000>

[after light_source]
White = <1.000, 1.000, 1.000, 0.000, 0.000>
"C:\Users\Mini\Documents\POV-Ray\v3.8-beta\scenes\_CodeScratchPad.pov" line 13:
Parse Warning: Expected pure RGB color expression,
unexpected filter and transmit components will have no effect.
-
"C:\Users\Mini\Documents\POV-Ray\v3.8-beta\scenes\_CodeScratchPad.pov" line 16:
Parse Error: Parse halted by #error directive: No
objects in scene

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?

- BE

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Le 2026-02-25 à 06:45, Bald Eagle a écrit :
> [before light_source]
> White = <1.000, 1.000, 1.000, 0.000, 0.000>
> 
> [after light_source]
> White = <1.000, 1.000, 1.000, 0.000, 0.000>
> "C:\Users\Mini\Documents\POV-Ray\v3.8-beta\scenes\_CodeScratchPad.pov" line 13:
> Parse Warning: Expected pure RGB color expression,
> unexpected filter and transmit components will have no effect.
> -
> "C:\Users\Mini\Documents\POV-Ray\v3.8-beta\scenes\_CodeScratchPad.pov" line 16:
> Parse Error: Parse halted by #error directive: No
> objects in scene
> 
> 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?
> 
> - BE
> 

Just tested, using this : #declare W = (White=1);
And got this :

W = <1.000, 0.000, 0.000, 1.000, 1.000>
NOT what I would expect.

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Alain Martel <kua### [at] videotronca> wrote:

> Just tested, using this : #declare W = (White=1);
> And got this :
>
> W = <1.000, 0.000, 0.000, 1.000, 1.000>
> NOT what I would expect.

Yes indeed, VERY strange.
I was going to do something like that, but I needed to head out.

what if plug (White=1) directly into a debug vstr statement?

- BE

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On 226-02-24 12:36 (-4), kurtz le pirate wrote:
> 
> How this <color White=1> is interpreted and why does it turn red?

I just tried it with different versions of POV-Ray.  It is red only with
POV-Ray 3.8 and the discontinued POV-Ray 3.7.1.  It is white for all
versions 3.5 to 3.7.0.10.

This appears to be a bug that was introduced in POV-Ray 3.7.1.

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Cousin Ricky <ric### [at] yahoocom> wrote:
> On 226-02-24 12:36 (-4), kurtz le pirate wrote:
> >
> > How this <color White=1> is interpreted and why does it turn red?
>
> I just tried it with different versions of POV-Ray.  It is red only with
> POV-Ray 3.8 and the discontinued POV-Ray 3.7.1.  It is white for all
> versions 3.5 to 3.7.0.10.
>
> This appears to be a bug that was introduced in POV-Ray 3.7.1.

Nice work, Richard.
So what are you doing that I didn't?
Because as you can see above/below, I'm using 3.8

[after light_source]
White = <1.000, 1.000, 1.000, 0.000, 0.000>
"C:\Users\Mini\Documents\POV-Ray\v3.8-beta\scenes\_CodeScratchPad.pov" line 13:
Parse Warning: Expected pure RGB color expression,
unexpected filter and transmit components will have no effect.

Are you outputting the color value with vstr(), or performing a render using
that light source?

I'm just trying to understand where this all goes off the rails, and where to
look under the hood.

- BE

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On 2026-02-25 16:11 (-4), Bald Eagle wrote:
> Cousin Ricky <ric### [at] yahoocom> wrote:
>> On 226-02-24 12:36 (-4), kurtz le pirate wrote:
>>>
>>> How this <color White=1> is interpreted and why does it turn red?
>>
>> I just tried it with different versions of POV-Ray.  It is red only with
>> POV-Ray 3.8 and the discontinued POV-Ray 3.7.1.  It is white for all
>> versions 3.5 to 3.7.0.10.
>>
>> This appears to be a bug that was introduced in POV-Ray 3.7.1.
> 
> Nice work, Richard.
> So what are you doing that I didn't?
> Because as you can see above/below, I'm using 3.8

I just opened a bug report on GitHub, issue #486.
https://github.com/POV-Ray/povray/issues/486

> [after light_source]
> White = <1.000, 1.000, 1.000, 0.000, 0.000>
> "C:\Users\Mini\Documents\POV-Ray\v3.8-beta\scenes\_CodeScratchPad.pov" line 13:
> Parse Warning: Expected pure RGB color expression,
> unexpected filter and transmit components will have no effect.

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)`?

> Are you outputting the color value with vstr(), or performing a render using
> that light source?

Both.  My source code is in the GitHub report.

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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().

Post a reply to this message

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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