POV-Ray : Newsgroups : povray.beta-test : media & fog bug? : Re: media & fog bug? Server Time
15 Aug 2022 18:23:09 EDT (-0400)
  Re: media & fog bug?  
From: bob h
Date: 10 Dec 2001 03:58:29
Message: <3c147935@news.povray.org>
"Kevin Ellis" <kev### [at] tiscalicouk> wrote in message
news:3c146d1a@news.povray.org...
>
> "Ken" <tyl### [at] pacbellnet> wrote in message
> news:3C13F95B.E4E09D82@pacbell.net...
> > I am pretty sure that this falls into the "not a bug" category. I know
> > this problem was present in v3.1g and have seen someone suggest a work
> > around for it. I just can't seem to find the article in question at the
> > moment.
>
> Sorry Ken, but I'll have to disagree with you on this one as in my opinion
> it is definitely a bug. The work around that I have found is to use
> radiosity with the media on switch, but this is incredibly slow when the
> ground is an isosurface, but this is still not a complete solution.
>
> The media container in the example should contain clouds so I should get
> some shadow from just the clouds, at the moment the whole box casts a
shadow
> with the above radiosity solution I still get no shadows from the clouds.
I
> have been experimenting with media clouds since MegaPOV and have never
> experienced this problem before. I realise that POV v3.5 is not MegaPOV
it's
> just that MegaPOV seemed to have the correct behaviour, or maybe I was
just
> plain lucky and never ran into the problem, could someone please check
> MegaPOV for me as I no longer have it or v3.1 installed?

Admittedly the box container object itself does seem to cast a shadow when
it should not be.  I'm just uncertain of the fact myself.
For media transmit can cast shadows too now, although at transmit 1 there
shouldn't be anything to cast a shadow from the box alone.  Before, in
earlier MegaPOV versions media couldn't cast shadows unless filter was used
instead (correct me if I'm wrong on that, anyone) but it didn't hamper
regular objects.

I can get shadows from clouds to show up simply by using:

box {
  <-30000,700,-60000>/10
  <30000,900,60000>/10
  material {
    texture {
      pigment {rgbt 1}

    }

    interior {
      media {
        scattering {5, .01 extinction 1 eccentricity 0.005}
        method 2 // speedier
        intervals 1
        aa_level 4
        jitter 0.1
        density {
                marble
                density_map {
                        [0 rgb 10] [.25 rgb 0]
                        } frequency 2 turbulence 1 scale 500
        }
      }
    }

  }
  hollow
}

instead of the box object you have there now, plus I put keyword parallel
into the light source.
Anyway, it does look as if there might be a problem since the shadow is not
seen when looking from above the lowest part of the box.  It manifests
itself when viewed from under the box.  At least I think it does.


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