chore: add terrain surface config

src/utils/world/terrainSurfaceColor.ts

@@ -0,0 +1,51 @@
+import {
+  TERRAIN_COLORS,
+  TERRAIN_SURFACE_COLOR_TOLERANCE,
+  type TerrainColorKey,
+} from "@/data/world/terrainConfig";
+import type { TerrainSurfaceRgb } from "@/types/world/terrainSurface";
+
+export function colorMatchesTerrainSurface(
+  r: number,
+  g: number,
+  b: number,
+  targetRgb: TerrainSurfaceRgb,
+  tolerance: number = TERRAIN_SURFACE_COLOR_TOLERANCE,
+): boolean {
+  return (
+    Math.abs(r - targetRgb[0]) <= tolerance &&
+    Math.abs(g - targetRgb[1]) <= tolerance &&
+    Math.abs(b - targetRgb[2]) <= tolerance
+  );
+}
+
+export function getTerrainColorKeyFromRgb(
+  r: number,
+  g: number,
+  b: number,
+): TerrainColorKey | null {
+  for (const [key, config] of Object.entries(TERRAIN_COLORS)) {
+    if (colorMatchesTerrainSurface(r, g, b, config.rgb)) {
+      return key as TerrainColorKey;
+    }
+  }
+
+  return null;
+}
+
+export function isGrassTerrainColor(r: number, g: number, b: number): boolean {
+  const key = getTerrainColorKeyFromRgb(r, g, b);
+  return key !== null && TERRAIN_COLORS[key].kind === "grass";
+}
+
+export function getGrassTipColorFromRgb(
+  r: number,
+  g: number,
+  b: number,
+): string | null {
+  const key = getTerrainColorKeyFromRgb(r, g, b);
+  if (key === null) return null;
+
+  const terrainColor = TERRAIN_COLORS[key];
+  return "grassTipColor" in terrainColor ? terrainColor.grassTipColor : null;
+}