feat: birch

scripts/gen-assets.ts

@@ -126,6 +126,18 @@ const bark: Shade = (x, y) => {
   return [92 + n + grain + crack, 66 + n * 0.8 + grain * 0.6 + crack, 44 + n * 0.6 + crack, 255]
 }
 
+// Silver birch bark: papery near-white with faint grey mottle and the dark
+// horizontal lenticel dashes that make a birch read as a birch.
+const birch: Shade = (x, y) => {
+  const n = noise(x, y) * 8
+  // Dark dashes: short random runs on a few rows, wrapping the trunk horizontally.
+  if (y % 8 < 3 && noise(Math.floor(x / 6), Math.floor(y / 8)) > 0.3) {
+    return [38 + n, 38 + n, 40 + n, 255]
+  }
+  const smudge = noise(Math.floor(x / 10), Math.floor(y / 10)) < -0.4 ? -22 : 0
+  return [216 + n + smudge, 218 + n + smudge, 214 + n + smudge, 255]
+}
+
 // Oak leaves: mid green, blotchy clumps with brighter highlights.
 const leaf: Shade = (x, y) => {
   const n = noise(x, y) * 26
@@ -249,6 +261,7 @@ const assets: Array<[string, number, number, Shade]> = [
   ["floor", 64, 64, floor],
   ["grass", 64, 64, grass],
   ["bark", 64, 64, bark],
+  ["birch", 64, 64, birch],
   ["leaf", 64, 64, leaf],
   ["needle", 64, 64, needle],
   ["rock", 64, 64, rock],