feat: expose terrain surface data

src/components/three/world/TerrainModel.tsx

@@ -2,10 +2,10 @@ import { useEffect, useMemo, useRef } from "react";
 import * as THREE from "three";
 import { useGLTF } from "@react-three/drei";
 import { useThree } from "@react-three/fiber";
+import { TERRAIN_MODEL_PATH } from "@/data/world/terrainConfig";
 import type { Vector3Tuple } from "@/types/three/three";
 import { optimizeGLTFSceneTextures } from "@/utils/three/optimizeGLTFScene";
 
-const TERRAIN_MODEL_PATH = "/models/terrain/model.gltf";
 const TERRAIN_DEFAULT_POSITION: Vector3Tuple = [0, 0, 0];
 
 interface TerrainModelProps {

src/data/world/terrainConfig.ts

@@ -1,5 +1,6 @@
 import type { TerrainSurfaceColorConfig } from "@/types/world/terrainSurface";
 
+export const TERRAIN_MODEL_PATH = "/models/terrain/model.gltf";
 export const TERRAIN_SURFACE_COLOR_TOLERANCE = 15;
 export const TERRAIN_WATER_HEIGHT = 0;
 export const TERRAIN_TILE_SIZE = 1;

src/hooks/world/useTerrainSurfaceData.ts

@@ -0,0 +1,63 @@
+import { useMemo } from "react";
+import * as THREE from "three";
+import { useGLTF } from "@react-three/drei";
+import { TERRAIN_MODEL_PATH } from "@/data/world/terrainConfig";
+import type {
+  TerrainSurfaceBounds,
+  TerrainSurfaceData,
+} from "@/types/world/terrainSurface";
+import { createTerrainSurfaceImageData } from "@/utils/world/terrainSurfaceSampler";
+
+function findTerrainBaseColorTexture(
+  scene: THREE.Object3D,
+): THREE.Texture | null {
+  let texture: THREE.Texture | null = null;
+
+  scene.traverse((child) => {
+    if (texture || !(child instanceof THREE.Mesh)) return;
+
+    const materials = Array.isArray(child.material)
+      ? child.material
+      : [child.material];
+
+    for (const material of materials) {
+      if (material instanceof THREE.MeshStandardMaterial && material.map) {
+        texture = material.map;
+        return;
+      }
+    }
+  });
+
+  return texture;
+}
+
+function createTerrainSurfaceBounds(
+  scene: THREE.Object3D,
+): TerrainSurfaceBounds {
+  scene.updateWorldMatrix(true, true);
+
+  const box = new THREE.Box3().setFromObject(scene);
+  return {
+    minX: box.min.x,
+    maxX: box.max.x,
+    minZ: box.min.z,
+    maxZ: box.max.z,
+  };
+}
+
+export function useTerrainSurfaceData(): TerrainSurfaceData | null {
+  const { scene } = useGLTF(TERRAIN_MODEL_PATH);
+
+  return useMemo(() => {
+    const texture = findTerrainBaseColorTexture(scene);
+    if (!texture) return null;
+
+    const imageData = createTerrainSurfaceImageData(texture);
+    if (!imageData) return null;
+
+    return {
+      bounds: createTerrainSurfaceBounds(scene),
+      imageData,
+    };
+  }, [scene]);
+}

src/types/world/terrainSurface.ts

@@ -34,3 +34,8 @@ export interface TerrainSurfaceSample {
   key: string | null;
   config: TerrainSurfaceColorConfig | null;
 }
+
+export interface TerrainSurfaceData {
+  bounds: TerrainSurfaceBounds;
+  imageData: ImageData;
+}