1638 Night

(meta linear-colour-space: 1)

(define
  ;; fade out any lines which are far away from the focal points
  interest (interp/build from: [0.2 1.5] to: [0 1] clamping: true))

;; call 'fun' for every point on a nXn grid on the canvas
(fn (grid n: 10 fun: 1)
    (define
      remap-x (interp/build from: [0 (- n 1)] to: [0 canvas/width])
      remap-y (interp/build from: [0 (- n 1)] to: [0 canvas/height]))
    (loop (y from: 0 to: n)
          (loop (x from: 0 to: n)
                (fn-call (fun position: [(interp/value from: remap-x t: x)
                                         (interp/value from: remap-y t: y)])))))


;; render the background grid
(define
  focal-bg-a (focal/build-point position: [525 ~ (gen/stray-int from: 525 by: 100)
                                           348 ~ (gen/stray-int from: 348 by: 100)]
                                distance: 750 ~ (gen/stray-int from: 750 by: 40)
                                falloff: linear)
  focal-bg-b (focal/build-point position: [542 ~ (gen/stray-int from: 542 by: 100)
                                           765 ~ (gen/stray-int from: 765 by: 10)]
                                distance: 891 ~ (gen/stray-int from: 891 by: 50)
                                falloff: linear)
  col-fn-bg (col/build-bezier a: (col/rgb r: 0.093 g: 0.208 b: 0.298 alpha: 0.247) ~ (gen/col)
                              b: (col/rgb r: 0.422 g: 0.034 b: 0.083 alpha: 0.373) ~ (gen/col)
                              c: (col/rgb r: 0.279 g: 0.904 b: 0.485 alpha: 0.503) ~ (gen/col)
                              d: (col/rgb r: 0.299 g: 0.192 b: 0.862 alpha: 0.987) ~ (gen/col)))



(fn (draw-element-bg position: [0 0])
    (define
      interest-a (focal/value from: focal-bg-a position: position)
      interest-b (focal/value from: focal-bg-b position: position)
      combined-interest (+ interest-a interest-b)
      alpha (interp/value from: interest t: combined-interest))
    (on-matrix-stack
      (translate vector: position)
      (rotate angle: (* combined-interest 334 ~ (gen/stray-int from: 334 by: 30)))
      (circle position: [0 0]
              colour: (col/set-alpha from: (col/value from: col-fn-bg t: interest-a) value: alpha)
              width: 41 ~ (gen/stray-int from: 41 by: 20)
              height: 461 ~ (gen/stray-int from: 461 by: 50)
              tessellation: 20)))

(grid n: 35 ~ (gen/stray-int from: 35 by: 5)
      fun: (address-of draw-element-bg))

;; render the foreground
(define
  focal-fg-a (focal/build-point position: [311 396] ~ (gen/int min: 0 max: 1000)
                                distance: 453 ~ (gen/int min: 0 max: 500)
                                falloff: linear)
  focal-fg-b (focal/build-point position: [157 178] ~ (gen/int min: 0 max: 1000)
                                distance: 386 ~ (gen/int min: 0 max: 600)
                                falloff: linear)
  col-fn-fg (col/build-bezier a: (col/rgb r: 0.762 g: 0.048 b: 0.407 alpha: 0.093) ~ (gen/col)
                              b: (col/rgb r: 0.474 g: 0.751 b: 0.507 alpha: 0.657) ~ (gen/col)
                              c: (col/rgb r: 0.179 g: 0.398 b: 0.683 alpha: 0.380) ~ (gen/col)
                              d: (col/rgb r: 0.425 g: 0.207 b: 0.393 alpha: 0.825) ~ (gen/col)))

(fn (draw-element-fg position: [0 0])
    (define
      interest-a (focal/value from: focal-fg-a position: position)
      interest-b (focal/value from: focal-fg-b position: position)
      combined-interest (+ interest-a interest-b)
      alpha (interp/value from: interest t: combined-interest))
    (on-matrix-stack
      (translate vector: position)
      (rotate angle: (* combined-interest 151 ~ (gen/stray-int from: 151 by: 30)))
      (circle position: [0 0]
              colour: (col/set-alpha from: (col/value from: col-fn-fg t: interest-a) value: alpha)
              width: 13 ~ (gen/stray-int from: 13 by: 7)
              height: 263 ~ (gen/stray-int from: 263 by: 50)
              tessellation: 20)))

(grid n: 36 ~ (gen/int min: 30 max: 40)
      fun: (address-of draw-element-fg))