"HarryK" <hko### [at] t-onlinede> wrote in message 
news:web.47c5c35db1099ea68e94e7980@news.povray.org...
> Hi folks
>
> I want to map a prism with n vertices, height_1=0 and height_2=0.001 onto 
> the
> surface of a sphere. Then I want to create the intersection of the sphere 
> and
> the mapped prism so that only the prism is visible. Can anybody help me?
>
> Thanks in advance
>
>
>      HarryK
>

Hi Harry,

I'm wondering whether a prism defined using a conic_sweep would do what you 
want.
You could use it to make a prism that's 0.001 units higher than the radius 
of the sphere you wish to map the prism onto. Then use two spheres to slice 
a 0.001 unit thick spherical layer out of the prism.

For example:

light_source {<2,7.5,-15>, rgb 1}
camera {location <0,1.4,-1> look_at <0,1,0>}

difference {
  intersection {
    prism {
      cubic_spline  conic_sweep
      0, 1.001, 14,
      // Outer Rim
      <-0.4,-0.4>, <-0.3,-0.3>, <0.3,-0.3>,
      <0.3,0.5>, <-0.3,0.5>, <-0.3,-0.3>,
      <-0.4,-0.2>
      // Inner Cutout
      <-0.1,-0.3>, <-0.2,-0.2>, <0.2,-0.2>,
      <0.2,0.4>, <-0.2,0.4>, <-0.2,-0.2>,
      <-0.3,-0.1>
    }
    sphere {0,1.001}
  }
  sphere {0,1}
  pigment {rgb <1,1,0>}
}

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