NetLogo Models Library:
Note: If you download the NetLogo application, every model in the Models Library is included.
This shows how to make turtles move along a perfect sphere. The first procedure moves turtles based a user-defined distance to be travelled; the second moves then based on a user-defined degree measure.
We use trigonometry to calculate the turtle's successive positions on the circle.
Turtles Circling, Circular Path Example