Adam Gibbons wrote:
> 
>...
> 
> but this is where I get stuck you may notice there is a rotation left in the
> statement, 

Ehh... No. Not ONE rotation "left".


When you do this;

sphere {
  <0.51, 0.8643750, 0>, 0.1
  rotate <10, -45, -20>
}

you make 3 rotations of the sphere relative to the axes.

First the sphere is rotated 10 degrees around the x-axis.
Then it is rotated -45 degrees around the y-axis.
And then -20 degrees around the z-axis.


And yes, you can use your "string" idea to visualize how 
they are rotated.

In the fist rotation your string is attached to the 
closest point on the x-axis.

In the second rotation your string is attached to the 
point that now has become the closest point on the y-axis. 

And in the third rotation your string is attached point 
that now has become the closest point on the z-axis.


(To see which way a rotation will go around an axis, 
let your left hand thumb point in the direction of the 
axis in question, and then look at the other fingers 
of your left hand. They will now point in the direction 
that the rotation will go if the angle is positive.)


If I can find some more spare time tomorrow, then I'll 
try to explain the calculations of the rotations.

Regards,

Tor Olav
-- 
mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html

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