fix(babylon_setup.js): get rid of placeholder meshes, avoid collisions in generation

src/babylon_setup.js

@@ -43,13 +43,6 @@ sphereMaterial.diffuseColor = new BABYLON.Color3(0.2, 0.55, 0.95);
 sphereMaterial.emissiveColor = new BABYLON.Color3(0.05, 0.12, 0.2);
 sphere.material = sphereMaterial;
 
-// Ground
-const ground = BABYLON.MeshBuilder.CreateGround("ground", { width: 14, height: 14 }, scene);
-const groundMaterial = new BABYLON.StandardMaterial("groundMaterial", scene);
-groundMaterial.diffuseColor = new BABYLON.Color3(0.12, 0.14, 0.17);
-groundMaterial.specularColor = BABYLON.Color3.Black();
-ground.material = groundMaterial;
-
 // Main render loop
 engine.runRenderLoop(() => {
     const level = sharedState.config.level;
@@ -71,6 +64,7 @@ let levelMeshes = [];
 let chestMap = new Map(); // key: "x,y" -> {mesh, opened}
 let keyChestKey = null;
 let exitBox = null;
+let exitGridPos = null; // track exit grid position for collision checking
 const cellSize = 2;
 
 function clearLevelMeshes() {
@@ -81,6 +75,7 @@ function clearLevelMeshes() {
     chestMap.clear();
     keyChestKey = null;
     if (exitBox) { try { exitBox.dispose(); } catch(e){}; exitBox = null; }
+    exitGridPos = null;
 }
 
 // Simple seeded RNG
@@ -220,8 +215,23 @@ function placeExit(grid, seed) {
     const dead = findDeadEnds(grid);
     const rng = seededRng(seed+1);
     if (dead.length === 0) return;
+    
+    // Filter out dead ends that have chests
+    const availableDead = dead.filter(([x, y]) => !chestMap.has(`${x},${y}`));
+    if (availableDead.length === 0) {
+        // Fallback: use any dead end if no chest-free spot available
+        // This shouldn't happen in normal cases
         const idx = Math.floor(rng() * dead.length);
         const [x,y] = dead[idx];
+        exitGridPos = { x, y };
+        // Continue below
+    } else {
+        const idx = Math.floor(rng() * availableDead.length);
+        const [x,y] = availableDead[idx];
+        exitGridPos = { x, y };
+    }
+    
+    const [x,y] = exitGridPos;
     const halfW = (grid[0].length * cellSize) / 2;
     const halfH = (grid.length * cellSize) / 2;
     const ex = x*cellSize - halfW + cellSize/2;
@@ -238,7 +248,16 @@ function spawnCameraAt(grid) {
     const h = grid.length, w = grid[0].length;
     for (let y = 1; y < h-1; y++) {
         for (let x = 1; x < w-1; x++) {
-            if (grid[y][x] === 0) {
+            // Skip walls
+            if (grid[y][x] !== 0) continue;
+            
+            // Skip chests
+            if (chestMap.has(`${x},${y}`)) continue;
+            
+            // Skip exit
+            if (exitGridPos && exitGridPos.x === x && exitGridPos.y === y) continue;
+            
+            // Found valid spawn point
             const halfW = (w * cellSize) / 2;
             const halfH = (h * cellSize) / 2;
             const px = x*cellSize - halfW + cellSize/2;
@@ -251,7 +270,6 @@ function spawnCameraAt(grid) {
             return;
         }
     }
-    }
 }
 
 function generateLevel() {