This isn't really a bug, and I think this has always been like this, but it
seems to me that spiral2 doesn't operate as described:

"The spiral2 pattern creates a double spiral that winds around the z-axis
similar to spiral1 except that it has two overlapping spirals which twist in
opposite directions. "

When looking at the pattern it seems to be rather a mix of spiral 1 and
radial.  One set of arms spiralling, and the other set radiating.

-tqg

sample code:

---start---

camera {location  z*4 look_at 0}

light_source {0
  color 1
  translate z*4
}

box{-1 1
  pigment{
    spiral2 10
    color_map{
      [0.0 rgb 1]
      [0.5 rgb 1]
      [0.5 rgb 0]
      [1.0 rgb 0]

    }
  }
}

---end---

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Also on the same topic:


In spiral1 and spiral2 in the docs:

The spiral1 pattern creates a spiral that winds around the z-axis...
...The Number_of_Arms value determines how may arms are winding around the
y-axis.


The spiral2 pattern creates a double spiral that winds around the z-axis...
...The Number_of_Arms value determines how may arms are winding around the
y-axis.

these seem to be contradictory statements, I think spiral winds around the
z-axis as first stated, not the y-axis.

-tgq

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