The listed script yields erronious results with or without
the "open" keyword in the prism commented out.

What is expected is a closed truncated prism.  What is
observed is an open truncated prism with a misplaced face.

This has been checked on 3.1r1 and a patched 3.02 code so
far with identical results.  For 3.1r1 it was checked
against the official POV for W95 and on the SuperPatch.
I realize only the official version is supported here,
but I report these facts for completeness -- it fails
on the official version.  Thus it appears the bug
is in the core rendering code for this primitive.

Dan

==============================

#declare V0 = <0, -3, 0>;
#declare V1 = V0 + <-5, 9, -8>;

camera {
  location V1
  look_at V0
}

light_source {
  V1
  color rgb 0.5
}
light_source {
  V1 * <-1, 1, 1>
  color rgb 0.5
}


prism {
  linear_spline
  conic_sweep
  -4, -3,
  4,
  <1, 1>, <-1, 1>, <-1, -1>, <1, -1>
  //open
  pigment { color rgb 1 } 
  finish { diffuse 0.5 ambient 0.5 }
}

-- 
http://www.flash.net/~djconnel/

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