Alain <aze### [at] qwertyorg> wrote:

> When using clipped_by, you remove everything that is outside the
> clipping object. In this case, that means the whole sphere as the first
> operation leaves only the surface of the sphere inside the box, then you
> remove that with the small sphere...
>

Ah yes, you're right. (That's why my clipped_by scene--*without* using
inverse--showed all-white media; all of the sphere had been removed!)

BTW, the 'special exception' I mentioned--of atmospheric media showing up even
with NO background or scene objects--was simply this:

camera {
  perspective
  location  <3, 3, -5>
  look_at   <.1, .8,  0>
  right     x*image_width/image_height
  angle 67
}

light_source {
  0*x
  color rgb 1
  translate <0,1,0>
}

// atmospheric media
media{
 scattering {1,rgb .0000001*<.7,1,.7> extinction .1}
 method 3
 intervals 1
 samples 300
 jitter .05
 }

Surprisingly, this successfully produces green media. Of course, rendering such
an idiotic scene serves no useful purpose. ;-) But it does show that there
actually *is* light-interacting media present, even with no objects in the scene
at all (other than the light); nothing *but* 'infinite rays.'

Ken

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