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.
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 |
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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?
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