"Chris B" <nom### [at] nomailcom> wrote in message 
news:4904fb3a@news.povray.org...
>
>>> I want to apply a color map to a torus so that the maps are applied as 
>>> wedges
>>> when viewing a cross-section of the torus.
>>> (I think this would be radially, but I am unsure.)
>
> To give you a pattern like a pie chart on the twin circular sections 
> through the torus, the only way I can think of is to build it up using 
> cone objects for textures rather than a color map. (I tried experimenting 
> with toroidal warp of a gradient and a radial texture, but failed to get 
> anything that mapped a color map in that way).


Interesting solution, if this is the thing being asked for.
Yeah, when I saw this message post I was going to try radial, then warp it, 
just to see if it could be done the way I figured would work right and it 
only gets nearly there:

// BEGIN wedges in torus cutaway
camera {
 location -3*z
 look_at 0
 rotate <30,0,0>
}

light_source {
 -99*z,
 1
 rotate <60,45,0>
}

difference {
 torus {
  1,0.5
 }
 plane {
  x,0
  rotate -90*y
 }
 texture {
  pigment {
   radial frequency 40
   color_map {
    [0.5 rgb 0.1]
    [0.5 rgb 0.9]
   }
   rotate 90*z
   warp {
    toroidal orientation y dist_exp 1 major_radius 1
   }
  } // pigment
 }
}
// END

For reasons unknown to me the pattern doesn't have the symmetry I expected. 
Maybe somebody out there understands why not...?

Bob H.

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