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

Post a reply to this message