"Bob Hughes" <omniverse charter net> wrote:
> "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.


Hi Guys,

So far, Bob got the idea of what I was looking for, but I still have one
concern.

I want to control how many sections there are, it seems to be related to
"radial frequency 30" and maybe the number of entries in the color_map.

Any suggestions on understanding this?


FYI,
I want to make some areas of the cross-section transparent (hence the rgbt).

I want to be able to animate the rotation of the colors around the section. That
seems controllable e.g. "rotate x * frame_number"


Fwiw Here's my version based on Bob's code:



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


sky_sphere {
  pigment {
    gradient y
    color_map {
      [0.0 rgb <0.6,0.7,1.0>]
      [0.7 rgb <0.0,0.1,0.8>]
    }
  }
}



light_source {
 -10*z,
 1
 //rotate <60,45,0>
}

light_source {
  <0, 0, 0>            // light's position (translated below)
  color rgb <1, 1, 1>  // light's color
  translate <-30, 30, -30>
}


difference {
 torus {
  1,0.5
 }
 torus {
  1,0.45
 }

 plane {
  x,0
  rotate -90*y
 }
 texture {
  pigment {
   radial frequency 30
   color_map {
      [0.25  color rgb <1,0,0>]
      [0.50 color rgb <0,1,0>]
//      [0.50 color rgbt <0,0,1>]
      [0.75 color rgbt <0,0,1,1>]
      [1.00 color rgbt <1,1,1>]
      [1.00 color rgbt <1,1,1>]
   }
   rotate 90*z
   rotate x * frame_number
   warp {
    toroidal orientation y dist_exp 1 major_radius 1
   }
  } // pigment
 }
}
// END

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