What is a Spirograph?
A Spirograph is formed by rolling a circle inside or outside of another
circle. The pen is placed at any point on the rolling circle.
If the radius of fixed circle is R, the radius of
moving circle is r, and the offset of the pen point in the
moving circle is O, then the equation of the resulting
curve is defined by:
x = (R+r)*cos(t) - (r+O)*cos(((R+r)/r)*t)
y = (R+r)*sin(t) - (r+O)*sin(((R+r)/r)*t)