Wasn't it Hadmut Danisch who wrote:
>Hi,
>
>I'd like to create a sphere with lines for longitudes and latitudes,
>which basically is just a white sphere with thin black lines on horizon
>and parallel to the horizon, and lines from north to south.
>
>How would I do this?
>
>I tried to apply a texture with a color map onto the surface of the
>sphere, but the gradient is just a linear vector of x,y,z and not
>a term (e.g. the angle phi cannot be used).
>
>Another approach would be to mix the sphere with very flat and black
>cylinders which are just a little big bigger than the sphere, but then
>the sphere is not perfect anymore.
>
>How could I get a sphere with those lines?

One way to do it is with layered textures.

sphere {0,1
 texture{
  pigment {gradient y
    colour_map{[0 rgb 1][0.1 rgb 0]}
    scale 0.15
  }      
 }
 texture {
  pigment {radial frequency 30
    colour_map{[0 rgb 1][0.1 rgbt <0,0,0,1>]}
  }
 }
}

The bottom layer is a gradient pigment with a small scale.

The upper layer is a radial pigment with a high frequency which is
mostly transparent so you can see the underlying gradient texture.

-- 
Mike Williams
Gentleman of Leisure

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