Spirograph

Julia implementation of the classic Spirograph toy.

To make a spirograph drawing, use the function

spirograph(a,b,offset,args...)

where

• a is the radius of the fixed wheel,
• b is the radius of the moving wheel, and
• offset is the distance from the center of the moving wheel to the pen location.

Here a and b are integers. The argument b may be negative, in which case the moving wheel glides along the inside of the fixed wheel. This is shown in the following diagram in which the red dot shows the pen location.

See also this diagram that shows the spirograph with a=14, b=-5, and offset=4 overlayed with a picture of the two wheels with a red dot for the pen location. (This picture was created using the mechanism function defined in the file diagram/mechanism.jl.) See also this animation.

The optional args can be used to change aspects of the plot.

For example:

spirograph(25,11,18,linecolor=:red)

produces this image:

We also provide the function spirograph! that operates exactly like spirograph but does not first clear the drawing window. In this way, multiple spirograph images can be combined.

julia> spirograph(40,-11,18,linecolor=:red)

julia> spirograph!(40,-11,16,linecolor=:blue)

julia> spirograph!(40,-11,14,linecolor=:green)

To save an image, use the savefig function from Plots. For example:

julia> using Spirograph, Plots

julia> spirograph(80,-33,45,linewidth=0.5)

julia> savefig("my-spiro.pdf")

Click here to see the result.