Regular polygon with strings

\copyright\; Roman\; Chijner\;,\;Heidelberg\;2013

N = 12 (slider from 3 to 100, step 1)
R = 3.8 (slider from 0 to 15, step 0.1)
n = 43 (slider from 1 to 300, step 1)
l1 = Sequence((R; 2 * π / N * i), i, 1, N)
r1 = Sequence(Element[l1, 1] * (1 - i / n), i, 0, n)
r2 = Sequence(Element[l1, 2] * (1 - i / n), i, 0, n)
r12 = Sequence(Segment[Element[r1, i], Element[r2, n - i + 1]], i, 1, n)
r3 = Sequence(Rotate[r12, 2 * π / N * i], i, 1, N)
r12' = Mirror(r12, Segment[Element[l1, 1], Element[l1, 2]])
r4 = Sequence(Rotate[r12', 2 * π / N * i], i, 1, N)