Hi,

here are a couple of them.




Basically, you start with a construction polygone, it can be anything from 2 to N side poly but I usually use 8, the more are used, the better looking the spiral. Each vertice of the poly serve as a center for an arc, you can start on any vertice and create the spiral in either CW or CCW direction, here I chose CW.

1- you start your first arc (small red arc) by setting it's center on the next vertice in the direction you chose, here CW.
2- you set the radius using the previous vertice, here the side of the poly and draw the arc until it's end point is on the tangent of the next side, here the red line.
3- the next arc center is on the next vertice in the direction you chose, here CW
4- the radius is set on the end of the previous arc and is drawn in the proper direction until it's end is on the tangent of the next side, here orange line.

You repeat steps 3 and 4 until you have the spiral you want, ie. number of turn, etc.

That's basically it, of course you'll need to join all the arcs in a single curve if needed.

I don't know if you can draw an arc (in Moi) from it's center, radius and angle but if it's possible it could simplify things a little.

Hope it's enough for you,
Felix