Bauble: hot air balloon

hot-air-balloon.janet

(def bottom (+ -100 -50))

(defn quantize [x y]
  (x * y | round / y))

(def envelope
  (sphere 100
  | union :r 50 (cylinder :y 25 50 | move :y -100)
  | scale
     :y (ss p.y bottom 100 1 0.80)
     :z (ss p.y bottom (+ bottom 75) 1 0.50)
  | onion 0.1
  | subtract :r 1 (half-space :-y (+ bottom 7))
  | radial :y 18 (fn [$ i]
    (resurface $
      (shade (hsv (/ p.y 100 | quantize 8) 1 1)
      | rotate :x -0.75
      )
    | scale :z (mod i 2 * 2 - 1)))
  | color (* c (ss occlusion 0 0.75 0 1))
  | fresnel))

(def flame
  (cone :-y 50 403
  | union :r 10 (cone :y 31 148)
  | bounded-offset 30 :threshold 10
    (perlin (- (* p [0.05 0.025 0.05]) [0 (* 5 t) 0]))
  | color (+ (* [1 1 0.7] (ss p.y 0 243))
    (mix [1 0.25 0] [1 1 0] (- normal.y)))
  | slow 0.25
  | move :y -72))

(def basket
  (box 50
  | onion 10
  | subtract :r 10
    (half-space :y (+ 29 (pow (p.xz / 15) 2 | sum)))
  | offset (* 0.25 (+
    (cos (min (abs p.xz) * 3 + (step (sin (* 2 p.y)) 0 * pi/2)) | abs)
    (sin (p.y * 1) | abs)))
  | shade (hsv 0.10 0.54 0.88)
  | union
    (box [66 5 10] :r 5
    | move [0 (+ 48 (pow (p.x / 15) 2)) 55]
    | rotate :y (- tau/8)
    | mirror :x :z :r 10
    | rotate :y tau/8
    | shade [0.4 0.05 0.1] :gloss 3 :shine 0.5
    | fresnel)))

(union
  (envelope
  | color (+ c (* 0.1 [1 1 0]
    (ss (distance p [0 bottom 0]) 0 150 1 0)
    (perlin [(* 5 t) 0]))))
  (flame | scale 0.1 | move :y bottom)
  (basket | scale 0.2 | move :y (- bottom 40))
| move :y 75)