Circles zooming

circles.elm

import Mouse

main = lift scene v

scene : Float -> Element
scene v = collage 600 600 (objs v ++ [
    toForm <| plainText (show v)])

objs : Float -> [Form]
objs factor = map (render factor) <| filter (pred factor) [30,20,10,5]

render : Float -> Float -> Form 
render f x = filled (hsla (x/50*pi) 0.5 0.5 (min 1 (f*x/100))) <| circle (f*x)

pred n f = n * f >= 30

v : Signal Float
v = lift (f . toFloat . fst) Mouse.position

f x = range 0 10 . (\x -> x / 20) <| (x - 50)

min x y = if x < y then x else y
max x y = if x > y then x else y

range x y v = max x (min v y)