"Kenneth" <kdw### [at] gmailcom> wrote:
> "omniverse" <omn### [at] charternet> wrote:
> > "Kenneth" <kdw### [at] gmailcom> wrote:
>
> > >
> > > Adding an identical pure-color ABSORPTION media (or even its complementary
> > > color)-- to try and *force* some opacity-- doesn't work either.
> > >
> >
> > Trying things the following scene looks like it works okay, except for edges
> > where I attempted to keep it from being like a solid object... In this case
> > density rgb 5, instead of only 1, could be good enough.
> >
> > // test laser beam
>
> I just discovered that you're right (and I was wrong, about this particular
> case): A pure-color emitting media like <1,0,0>, along with an additional
> absorption media of the COMPLEMENTARY color (<0,1,1>) and same density, does
> indeed show true opacity, when both densities are made high enough. I guess I
> didn't crank up the density enough in my original experiment(?). I see that the
> same also applies to absorption + absorption (!), and
> scattering + absorption, when using the complementary color. Thanks for your
> scene code; I probably wouldn't have noticed this otherwise, in my own test
> code.
>
> Perhaps the 1's and 0's in both medias serve to 'cancel' any 'zero effect', when
> used together.
>
> So, the 'transparent color' effect (no opacity) is apparent only when using a
> SINGLE pure-color media (or when adding the *same*-color absorption media to
> it.)
>
> But I'm still curious about the effect of zero(s) in a single media... ;-)

Well, let's think about it here.

Additive only if singular densities exist in the singular media, so zero plus
whatever other color equals the other color(s).
Yet pair up density statements in the single media and those
colors(density*absorption, or emission or both) multiply densities, therefore
zero anywhere makes same color 0. Or rather factored by that, depending on type
of media.

Or so I believe. Seems the more I talk the less sense I make to myself, possibly
everyone else too!

Where I get most confused is that factoring in of background colors, which I
think always remain additive (emitting) or subtractive (absorbing) regardless of
the media itself.

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