"Danny" <danzaetz> wrote:
> Alain <aze### [at] qwertygov> wrote:
> > Danny nous apporta ses lumieres ainsi en ce 2004/05/17 16:39... :
> >
> > >Alain <aze### [at] qwertygov> wrote:
> > >
> > >
> > >>Danny nous apporta ses lumieres ainsi en ce 2004/05/17 05:23... :
> > >>
> > >>
> > >>
> > >>>Alain <aze### [at] qwertygov> wrote:
> > >>>
> > >>>
> > >>>
> > >>>I used exactly what you told me, and I got a cylinder with white edges that
> > >>>fades to nothing in the middle (without any red at all), and even those
> > >>>white edges disappear as the cylinder continues on.  I'm using POV-Ray 3.5,
> > >>>and here is the code I used:
> > >>>
> > >>>cylinder{<100,0,0>,<0,0,0>, .20
> > >>>        texture {
> > >>>   pigment { color rgbt 1}
> > >>>   finish{reflection 0}}
> > >>>      interior{media{emission rgb 1
> > >>>      density{ cylindrical
> > >>>      color_map{[0 rgb 0][0.5 rgb<1,0,0>][0.98 rgb 1][1 rgb 2]}
> > >>>      }}}
> > >>>      hollow
> > >>>      translate<0,0,2>
> > >>>      }
> > >>>
> > >>>Can you tell me what I'm doing wrong, and how to fix it?
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>Set the radius of the cylinder to 1, then rescale it by scale<.2,1,.2>
> > >>just before you rotate it.
> > >>You don't need to set finish{reflection 0}}, it's the default value.
> > >>Set your cylinder verticaly, as it's the orientation of the cylindrical
> > >>pattern, then rotate the whole thing.
> > >>...
> > >>scale<0.2, 1, 0.2>
> > >>rotate -90*z
> > >>translate<0, 0, 2>
> > >>}// that's the last brace
> > >>
> > >>Alain
> > >>
> > >>
> > >
> > >OK, now it looks good when I don't scale it, but scaling it seems to mess it
> > >up.
> > >When I scale it up it still seems to look OK, except the inner white part
> > >has become enlarged disproportionately.  But when I scale it down, I lose
> > >the white part completely, and all I have is a very dimly red cylinder.
> > >Can you explain why it's doing this and how I can make it scale down right?
> > >
> > >
> > >
> > Try lowering the 0.98 to a smaler value, thus enlarging the central
> > part. As it is now, the white center part only have a radius of 0.02
> > units and may disappears when scaled down or if the image is generated
> > at a low resolution.
> > Don't scale only the media but the whole cylinder containing the media.
> >
> > Alain
>
> Thanks a lot for all your help!  I managed to fix the scaling problem by
> multiplying the brightness of all the color map values by 5.  I guess this
> is because there is less matter in the media to show up if I scale it down
> to a fifth of its size.
> Thanks,
> Danny

I've got another problem. For some strange reason, my media cylinder is
acting like a convex lens. It's showing an narrowed image on the right side
of the cylinder of an object behind and to the left of it.  It's refracting
(not reflecting) light, I think.  When I zoom out, it looks like ugly white
lines on the side of my laser. How do I get rid of them?

Danny

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