This was a little script I threw together when I had trouble with the
coordinate system.  It helped me figure out how things would move and/or
rotate.  I'm posting it here so, perhaps, it can help others.

#declare marker =
  union {
    cylinder { <0,0,0>,<1,0,0>,.1 pigment { rgb <1,0,0> } }
    cone { <1.3,0,0>,0,<1,0,0>,.2 pigment { rgb <1,0,0> } }
    cylinder { <0,0,0>,<0,1,0>,.1 pigment { rgb <0,1,0> } }
    cone { <0,1.3,0>,0,<0,1,0>,.2 pigment { rgb <0,1,0> } }
    cylinder { <0,0,0>,<0,0,1>,.1 pigment { rgb <0,0,1> } }
    cone { <0,0,1.3>,0,<0,0,1>,.2 pigment { rgb <0,0,1> } }
  }

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That's pretty nifty!

If only I could remember which way to rotate...

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Slashdolt <jer### [at] questsoftwarecom> wrote:
> If only I could remember which way to rotate...

  It's simple. There's a good way described in the documentation.
Using your left hand, point your thumb towards the positive axis around
which you want to rotate; your other fingers will tell you the direction
of the rotation (when rotating by a positive angle).

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

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>   It's simple. There's a good way described in the documentation.
> Using your left hand, point your thumb towards the positive axis around
> which you want to rotate; your other fingers will tell you the direction
> of the rotation (when rotating by a positive angle).
>
Yeah, I remember reading that, but then I couldn't remember, "How was it
that I was supposed to hold my thumb?"  ;-)  I generally just think, "Oops!
The other direction."  Although it does make things more difficult when
rotating around more than one axis at a time...

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