From 2b08665508668d9fc64dc0da1171f1d7e2cb9a78 Mon Sep 17 00:00:00 2001
From: Tom Boullay <tom@famille-boullay.fr>
Date: Mon, 25 May 2026 17:54:57 +0200
Subject: [PATCH] fix(map): align path preview with terrain projection

---
 src/utils/world/terrainSurfaceSampler.ts | 4 ++--
 src/world/paths/PathSystem.tsx           | 6 +++++-
 src/world/paths/usePathTileData.ts       | 8 ++++++--
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/utils/world/terrainSurfaceSampler.ts b/src/utils/world/terrainSurfaceSampler.ts
index c80fc2e..43eacb9 100644
--- a/src/utils/world/terrainSurfaceSampler.ts
+++ b/src/utils/world/terrainSurfaceSampler.ts
@@ -91,8 +91,8 @@ export function terrainSurfaceUvFromXZ(
 ): TerrainSurfaceUv {
   const width = bounds.maxX - bounds.minX;
   const depth = bounds.maxZ - bounds.minZ;
-  let u = width === 0 ? 0 : (x - bounds.minX) / width;
-  let v = depth === 0 ? 0 : (z - bounds.minZ) / depth;
+  let u = width === 0 ? 0 : x / width + 0.5;
+  let v = depth === 0 ? 0 : z / depth + 0.5;
 
   if (projection?.flipX) {
     u = 1 - u;
diff --git a/src/world/paths/PathSystem.tsx b/src/world/paths/PathSystem.tsx
index be8c8c2..7cad014 100644
--- a/src/world/paths/PathSystem.tsx
+++ b/src/world/paths/PathSystem.tsx
@@ -62,7 +62,11 @@ function PathDebugPreview({
       const instance = instances[i];
       if (!instance) continue;
 
-      position.set(instance.position[0], 0.08, instance.position[2]);
+      position.set(
+        instance.position[0],
+        instance.position[1] + 0.08,
+        instance.position[2],
+      );
       matrix.compose(position, quaternion, scale);
       instancedMesh.setMatrixAt(i, matrix);
     }
diff --git a/src/world/paths/usePathTileData.ts b/src/world/paths/usePathTileData.ts
index b024dd0..d0fd8c6 100644
--- a/src/world/paths/usePathTileData.ts
+++ b/src/world/paths/usePathTileData.ts
@@ -1,5 +1,6 @@
 import { useMemo } from "react";
 import { TERRAIN_SURFACE_PROJECTION } from "@/data/world/terrainConfig";
+import { useTerrainHeightSampler } from "@/hooks/three/useTerrainHeight";
 import { useTerrainSurfaceData } from "@/hooks/world/useTerrainSurfaceData";
 import type { Vector3Tuple } from "@/types/three/three";
 import { sampleTerrainSurfaceAtXZ } from "@/utils/world/terrainSurfaceSampler";
@@ -25,6 +26,7 @@ function createSampleCenters(min: number, max: number, step: number): number[] {
 
 export function usePathTileData(): MapAssetInstance[] {
   const terrainSurfaceData = useTerrainSurfaceData();
+  const terrainHeight = useTerrainHeightSampler();
 
   return useMemo(() => {
     if (!terrainSurfaceData) return [];
@@ -55,8 +57,10 @@ export function usePathTileData(): MapAssetInstance[] {
 
         if (sample.key !== PATH_SURFACE_KEY) continue;
 
+        const height = terrainHeight.getHeight(x, z) ?? 0;
+
         instances.push({
-          position: [x, 0, z],
+          position: [x, height, z],
           rotation: [...PATH_TILE_ROTATION] as Vector3Tuple,
           scale: [...PATH_TILE_SCALE] as Vector3Tuple,
         });
@@ -64,5 +68,5 @@ export function usePathTileData(): MapAssetInstance[] {
     }
 
     return instances;
-  }, [terrainSurfaceData]);
+  }, [terrainHeight, terrainSurfaceData]);
 }