"Kenneth" <kdw### [at] gmailcom> wrote:

> Or perhaps I'm misunderstanding what the ShaderToy reference means, and why it
> cautions against a 0.0 value in a color vector being multiplied.

Yes, it is a bit hard, if not impossible to grasp the "why" without a greater
overview of the context.

Rather than think of it from the narrow perspective of what _you_ might do to
the color, think about what might happen to the color once the object pigmented
with it is placed into a scene, in proximity to another object that _does_ have
a red color, or is lit with a light source that has a red component.   Then
POV-Ray (or any other graphics software) would calculate what color the camera
would see by multiplying the base color by some fraction of the lighting or
radiosity, etc.

And THAT's the take-away message I got from following along in a few tutorials
and live coding sessions.

I mean, we can always ADD <r, 0, 0> to a color to give it some red first, and
THEN multiply it, but the idea is always have that little bit in there that can
be operated upon by all the complexities of the scene and lighting interactions,
so that we don't have to think about it every time, and make it even more
difficult for newbies to debug "Why do my scene objects look so _______ ?"

I hope that clears it up a little bit.

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