honeylisp/editor/tiledraw/iigs.fnl

(local {: putpixel : make-canvas} (require :editor.tiledraw))
(local tiles (require :game.tiles))

; converted from http://pixeljoint.com/forum/forum_posts.asp?TID=12795 (db16)
; maybe check out https://lospec.com/palette-list ?
(local pal [[1 0 1]  [4 2 3]  [3 3 6]  [4 4 4]  [8 4 3]   [3 6 2]   [13 4 4]  [7 7 6]
            [5 7 12] [13 7 2] [8 9 10] [6 10 2] [13 10 9] [6 12 12] [13 13 5] [13 14 13]])
(fn gs-to-rgb [color] (icollect [_ v (ipairs (or color [0 0 0]))] (* v 0x11)))

(fn spritegen-for-size [w h]
  (fn [tile]
    (when tile (make-canvas w h (fn [canvas]
      (love.graphics.clear 0 0 0 0)
      (for [y 0 (- h 1)]
        (for [x 0 (- w 1)]
          (let [ibyte (+ (* y w) x 1)
                byte (string.byte (tile:sub ibyte ibyte))
                mask (bit.band (bit.rshift byte 4) 0xf)
                color (bit.band byte 0xf)
                rgb (if (= mask 0) (gs-to-rgb (. pal (+ color 1))) [255 0 255])]
            (when (= mask 0) (putpixel x y rgb))))))))))

(local tile-to-sprite (spritegen-for-size 16 16))

(fn spritegen-for-style [name]
  (let [{: tilew : tileh} (tiles.style name)]
    (spritegen-for-size tilew tileh)))

{: tile-to-sprite : spritegen-for-size : spritegen-for-style : pal : gs-to-rgb}