feat(map): generate path tiles from terrain colors

src/world/GameMap.tsx

@@ -24,6 +24,7 @@ import { GeneratedMapNodeInstance } from "@/world/map-generated/GeneratedMapNode
 import { isGeneratedMapModelName } from "@/world/map-generated/generatedMapModelConfig";
 import { MapInstancingSystem } from "@/world/map-instancing/MapInstancingSystem";
 import { isInstancedMapNodeName } from "@/world/map-instancing/mapInstancingConfig";
+import { PathSystem } from "@/world/paths/PathSystem";
 import { VegetationSystem } from "@/world/vegetation/VegetationSystem";
 import type { SceneLoadingChangeHandler } from "@/types/world/sceneLoading";
 import { logger } from "@/utils/core/Logger";
@@ -257,6 +258,7 @@ export function GameMap({
         ))}
       </group>
       <MapInstancingSystem />
+      <PathSystem />
       <VegetationSystem />
       {isMapModelVisible("terrain", { groups, models }) ? (
         <TerrainModel />

src/world/paths/PathSystem.tsx

@@ -0,0 +1,20 @@
+import { InstancedMapAsset } from "@/world/map-instancing/InstancedMapAsset";
+import { PATH_TILE_MODEL_PATH } from "@/world/paths/pathConfig";
+import { usePathTileData } from "@/world/paths/usePathTileData";
+
+export function PathSystem(): React.JSX.Element | null {
+  const pathTiles = usePathTileData();
+
+  if (pathTiles.length === 0) {
+    return null;
+  }
+
+  return (
+    <InstancedMapAsset
+      castShadow={false}
+      instances={pathTiles}
+      modelPath={PATH_TILE_MODEL_PATH}
+      receiveShadow
+    />
+  );
+}

src/world/paths/pathConfig.ts

@@ -0,0 +1,10 @@
+import { TERRAIN_COLORS, TERRAIN_TILE_SIZE } from "@/data/world/terrainConfig";
+
+export const PATH_SURFACE_KEY = "chemin";
+export const PATH_TILE_MODEL_PATH = TERRAIN_COLORS.chemin.modelPath;
+export const PATH_TILE_SIZE =
+  TERRAIN_COLORS.chemin.tileSize ?? TERRAIN_TILE_SIZE;
+export const PATH_TILE_SAMPLE_STEP = 2;
+export const PATH_TILE_MAX_COUNT = 1500;
+export const PATH_TILE_ROTATION = [0, 0, 0] as const;
+export const PATH_TILE_SCALE = [1, 1, 1] as const;

src/world/paths/usePathTileData.ts

@@ -0,0 +1,68 @@
+import { useMemo } from "react";
+import { useTerrainSurfaceData } from "@/hooks/world/useTerrainSurfaceData";
+import type { Vector3Tuple } from "@/types/three/three";
+import { sampleTerrainSurfaceAtXZFromRaycast } from "@/utils/world/terrainSurfaceSampler";
+import type { MapAssetInstance } from "@/world/map-instancing/useMapInstancingData";
+import {
+  PATH_TILE_MAX_COUNT,
+  PATH_SURFACE_KEY,
+  PATH_TILE_ROTATION,
+  PATH_TILE_SAMPLE_STEP,
+  PATH_TILE_SCALE,
+} from "@/world/paths/pathConfig";
+
+function createSampleCenters(min: number, max: number, step: number): number[] {
+  const start = Math.ceil(min / step) * step + step * 0.5;
+  const centers: number[] = [];
+
+  for (let value = start; value <= max; value += step) {
+    centers.push(value);
+  }
+
+  return centers;
+}
+
+export function usePathTileData(): MapAssetInstance[] {
+  const terrainSurfaceData = useTerrainSurfaceData();
+
+  return useMemo(() => {
+    if (!terrainSurfaceData) return [];
+
+    const instances: MapAssetInstance[] = [];
+    const xCenters = createSampleCenters(
+      terrainSurfaceData.bounds.minX,
+      terrainSurfaceData.bounds.maxX,
+      PATH_TILE_SAMPLE_STEP,
+    );
+    const zCenters = createSampleCenters(
+      terrainSurfaceData.bounds.minZ,
+      terrainSurfaceData.bounds.maxZ,
+      PATH_TILE_SAMPLE_STEP,
+    );
+    const raycastY = terrainSurfaceData.bounds.maxY + 10;
+
+    for (const x of xCenters) {
+      for (const z of zCenters) {
+        if (instances.length >= PATH_TILE_MAX_COUNT) return instances;
+
+        const sample = sampleTerrainSurfaceAtXZFromRaycast(
+          terrainSurfaceData.imageData,
+          terrainSurfaceData.raycastTarget,
+          x,
+          z,
+          raycastY,
+        );
+
+        if (sample?.key !== PATH_SURFACE_KEY) continue;
+
+        instances.push({
+          position: [x, 0, z],
+          rotation: [...PATH_TILE_ROTATION] as Vector3Tuple,
+          scale: [...PATH_TILE_SCALE] as Vector3Tuple,
+        });
+      }
+    }
+
+    return instances;
+  }, [terrainSurfaceData]);
+}