What
is it? |
This project
shows a new way to create a circle with StarLogo. The turtles don't draw
a circle. Rather, the turtles arrange themselves into a circle, based on
their interactions with one another.
Each turtle
follows two simple rules: (1) it tries to keep a certain distance from
each of its two "neighbors", and (2) it gently "repels" the group as a
whole, trying to move away from the other turtles. With these two rules,
the turtles arrange themselves into a circle. |
How
to Use It |
Click
the setup button to set up the turtles. Click the adjust
button, then click the repel button.
The num
slider controls the total number of turtles.
The desired-distance
slider controls the distance that each turtle tries to keep from its neighbors.
The convergence
slider controls how quickly the turtles move toward the desired distance
from their neighbors.
The repel-strength
slider controls how strongly each turtle tries to move away from the group
as a whole. |
 |
|
Things
to Notice |
When you click
on the adjust button, the turtles "relax" into a pattern with
each turtle at the desired distance from its two neighbors. There are many
ways for each turtle to be equidistant from its two neighbors. When you
turn on the repel button, the turtles move to a different "solution":
a circle.
After the turtles
have formed a circle, reduce the desired-distance slider and the
circle shrinks. Increase the desired-distance and the circle expands. |
Explorations |
Change the
setup
procedure so that the turtles start in random positions all over the screen
(not clustered near the middle, as in the original
setup procedure).
Then turn on the adjust and repel sliders. Do the turtles
still form a circle?
What happens
if you turn on only the repel button (and not the adjust
button)
What happens
if you perturb the circle? |