A programm that draws spirograph patterns using up to 4 different Trochoids: Hypotrochoids, Epitrochoids, Hypocycloid and Epicycloids. Here are some example images generated with Spiro:

Make sure you have gloss installed. To install gloss use:
$ cabal update
$ cabal install gloss

Clone this repo:
$ git clone https://github.com/lkamil/spiro.git
$ cd spiro

Compile and run Spiro.hs using:
$ ghc -o spiro Spiro.hs && ./spiro

To create different patterns play around with the 5 parameters: density, innerRadius, outerRadius, distance and loops.
Here you can look up what these parameters mean in detail.

-- parameters
innerRadius = 1     -- radius of the inner circle
outerRadius = 112   -- radius of the outer circle
distance    = 100   -- distance from the centre of the inner circle
loops       = 2     -- count of 360° loops
density     = 2000  -- higher density results in smoother lines

To generate a pattern you can combine all 4 trochoids or less. To add or delete a trochoid modify the array in the
function spiro.

-- this version of spiro draws a dark blue epitrochoid on top of a light green epicycloid
-- on top of a ... you get the point :)
spiro :: Picture
spiro = pictures
    [ color darkred $ line drawHypotrochoid
    , color rosee $ line drawHypocycloid
    , color lightgreen $ line drawEpicycloid
    , color darkblue $ line drawEpitrochoid
    ]

Feel free to change the colors or add new colors using the function makeColorI that takes 3 RGB values (from 0 to 255) and an alpha value that sets the transparency.

seagrean = makeColorI 32 178 170 255