slab panel

packages/core/src/hooks/spatial-grid/spatial-grid-manager.ts

@@ -435,7 +435,7 @@ export class SpatialGridManager {
     const slabMap = this.slabsByLevel.get(levelId)
     if (!slabMap) return 0
 
-    let maxElevation = 0
+    let maxElevation = -Infinity
     for (const slab of slabMap.values()) {
       if (slab.polygon.length >= 3 && itemOverlapsPolygon(position, dimensions, rotation, slab.polygon, 0.01)) {
         const elevation = slab.elevation ?? 0.05
@@ -444,7 +444,7 @@ export class SpatialGridManager {
         }
       }
     }
-    return maxElevation
+    return maxElevation === -Infinity ? 0 : maxElevation
   }
 
   /**

packages/core/src/systems/wall/wall-system.tsx

@@ -151,6 +151,7 @@ export function generateExtrudedWall(
 
   const wallStart: Point2D = { x: wallNode.start[0], y: wallNode.start[1] }
   const wallEnd: Point2D = { x: wallNode.end[0], y: wallNode.end[1] }
+  // Wall height is adjusted by slab elevation (positive reduces, negative increases)
   const height = (wallNode.height ?? 2.5) - slabElevation
   const thickness = wallNode.thickness ?? 0.1
   const halfT = thickness / 2
@@ -244,7 +245,8 @@ export function generateExtrudedWall(
 
   // Rotate so extrusion direction (Z) becomes height direction (Y)
   geometry.rotateX(-Math.PI / 2)
-  if (slabElevation > 0) {
+  // Translate by slab elevation (works for both positive and negative values)
+  if (slabElevation !== 0) {
     geometry.translate(0, slabElevation, 0)
   }
   geometry.computeVertexNormals()