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Hello,
I found this in some very old code (2016) :
light_source {
<0, 100, 0>
color White=1
}
and with thise, the light in the scene is red.
of course, back to "normal" color White give white light.
How this <color White=1> is interpreted and why does it turn red?
--
kurtz le pirate
compagnie de la banquise
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kurtz le pirate <kur### [at] free fr> wrote:
> Hello,
>
>
> I found this in some very old code (2016) :
>
> light_source {
> <0, 100, 0>
> color White=1
> }
> How this <color White=1> is interpreted and why does it turn red?
Yeah, that's weird.
The parser is a strange and wondrous thing.
Presumably you are including colors.inc.
Can you output the color value of White as a 5D vector to the debug stream
before instantiating the light source, and then show what happens to it after?
- BE
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On 2026-02-24 12:36 (-4), kurtz le pirate wrote:
>
> How this <color White=1> is interpreted and why does it turn red?
Where does the identifier `White` come from? Like BE, I would like to
know its value.
My understanding of that syntax is that it compares each component of
`White` with 1. But if `White` comes from colors.inc, the
component-wise comparison would still end up as white. The only way I
can see this evaluating as red is if `White.red` is exactly 1, and
`White.green`, `White.blue`, `White.filter`, and `White.transmit` are
all something other than 1.
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On 25/02/2026 04:21, Cousin Ricky wrote:
> On 2026-02-24 12:36 (-4), kurtz le pirate wrote:
>>
>> How this <color White=1> is interpreted and why does it turn red?
>
> Where does the identifier `White` come from? Like BE, I would like to
> know its value.
White come from "colors.inc"
> My understanding of that syntax is that it compares each component of
> `White` with 1. But if `White` comes from colors.inc, the
> component-wise comparison would still end up as white. The only way I
> can see this evaluating as red is if `White.red` is exactly 1, and
> `White.green`, `White.blue`, `White.filter`, and `White.transmit` are
> all something other than 1.
>
I also thought that "=" was interpreted as a comparison operator.
But since “White” is defined by rgb 1, that doesn't explain anything.
--
kurtz le pirate
compagnie de la banquise
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[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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