"omniverse" <omn### [at] charternet> wrote:
> "Loren" <gre### [at] umnedu> wrote:
> >
> > I'm having great difficult getting emitting media (glowing red media, as in a
> > laser), in my scenes. First, a simple example which doesn't work:
> >
> > background { color White }
> >
> > sphere {
> >   <0, 1, 2>, 2
> >   texture {
> >     pigment { color rgbf 1 }
> >   }
> >   hollow
> >   interior{
> >        media{ emission Red intervals 30 samples 100,100 }
> >   }
> > }
>
> The pure white background is the trouble there, the emitting media can't
> subtract from that, yet scattering or absorbing media would.
>
> > even though it does work without the "media". What I'd really like to do is add
> > a red laser to the following scene, but all I get is a hollow tube. I've tried
> > both emitting and scattering media with no success. See especially the cylinder
> > that I've marked with a [+].
>
> Although the parameters have been needlessly cranked up, which I presume you did
> to try gaining a visible media, the problem is apparently the quartic "drop"
> object at the end of the scene file.
>
> If you add 'inverse' keyword to the "drop" the following will appear okay. I
> don't know much of anything about quartic but somehow it's applying its material
> to everything else without inverse being there.
>
> While hollow will also fix that emitting media visibility it doesn't rid the
> water material wrapping around the laser cylinder in version 3.7 (and 3.7.1-rc),
> however material isn't seen on this cylinder in v3.6.
>
> cylinder{ M1+5*y, M1, 0.1 pigment {rgbf 1}
> hollow on
>     interior
>     { media { emission <10,0.0,0.0> absorption <0,1,1> samples 5} }
> }

Realizing now I left 'absorption' in there (copy paste), laser light won't cause
a shadow like that.

And I should have mentioned you could use a cylindrical density map too, for
making the beam edges fade. Only need to scale appropriately.

Bob

Post a reply to this message