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

>
> Note the 'extinction' value of 0. Although scattering media's extinction
> is good
> for producing self-shadowing, it presently can't take a color vector, just a
> float value. As-is, it creates a *complementary* color in the media (nearly
> PURPLE in this case.) That's realistic, of course-- a colored cloud *should*
> filter out lighting of that color-- ...

Hmm, *is* that complementary-color self-shadowing 'realistic' or not? There are
two ways of looking at it: If the green cloud FILTERS the incoming
full-frequency light source, then it's not realistic-- the shadows within the
media should be GREEN, just like the cloud. But if the green cloud ABSORBS the
green color from the incoming light, then a complementary color IS correct. So--
to state the obvious-- 'extinction' in scattering media is actually ABSORPTION
media in disguise. The only problem that arises is, extinction can't be made a
different color (or NO color); it takes its cue from the scattering media's main
color.

There are actually two different ways to construct a colored media with varying
density. A simple example...

(1)
media{
    scattering{1, rgb 10*<.5,1,.5> extinction 2.0} // color is here
         density{
                spherical
                color_map{
                        [.12 rgb 0]
                        [.37 rgb 1]
                         }
                }
       }

Or..
(2)
media{
    scattering{1, 10 extinction 2.0}
         density{
                spherical
                color_map{
                        [.12 rgb 0]
                        [.37 rgb <.5,1,.5>] // color is here
                         }
                }
       }

I haven't actually tested one vs. the other, using the latest beta release. But
I would assume that they produce identical results.

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