draft item-system + elevation

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

@@ -1,11 +1,30 @@
-import type { AnyNode, ItemNode, WallNode } from '../../schema'
+import type { AnyNode, ItemNode, SlabNode, WallNode } from '../../schema'
 import { SpatialGrid } from './spatial-grid'
 import { WallSpatialGrid } from './wall-spatial-grid'
 
+/**
+ * Point-in-polygon test using ray casting algorithm.
+ * Returns true if point (px, pz) is inside the polygon defined by vertices.
+ */
+function pointInPolygon(px: number, pz: number, polygon: Array<[number, number]>): boolean {
+  let inside = false
+  const n = polygon.length
+  for (let i = 0, j = n - 1; i < n; j = i++) {
+    const xi = polygon[i]![0], zi = polygon[i]![1]
+    const xj = polygon[j]![0], zj = polygon[j]![1]
+
+    if ((zi > pz) !== (zj > pz) && px < ((xj - xi) * (pz - zi)) / (zj - zi) + xi) {
+      inside = !inside
+    }
+  }
+  return inside
+}
+
 export class SpatialGridManager {
   private floorGrids = new Map<string, SpatialGrid>() // levelId -> grid
   private wallGrids = new Map<string, WallSpatialGrid>() // levelId -> wall grid
   private walls = new Map<string, WallNode>() // wallId -> wall data (for length calculations)
+  private slabsByLevel = new Map<string, Map<string, SlabNode>>() // levelId -> (slabId -> slab)
 
   constructor(private cellSize = 0.5) {}
 
@@ -36,9 +55,18 @@ export class SpatialGridManager {
     return wall?.height ?? 2.5 // Default wall height
   }
 
+  private getSlabMap(levelId: string): Map<string, SlabNode> {
+    if (!this.slabsByLevel.has(levelId)) {
+      this.slabsByLevel.set(levelId, new Map())
+    }
+    return this.slabsByLevel.get(levelId)!
+  }
+
   // Called when nodes change
   handleNodeCreated(node: AnyNode, levelId: string) {
-    if (node.type === 'wall') {
+    if (node.type === 'slab') {
+      this.getSlabMap(levelId).set(node.id, node as SlabNode)
+    } else if (node.type === 'wall') {
       const wall = node as WallNode
       this.walls.set(wall.id, wall)
     } else if (node.type === 'item') {
@@ -79,7 +107,9 @@ export class SpatialGridManager {
   }
 
   handleNodeUpdated(node: AnyNode, levelId: string) {
-    if (node.type === 'wall') {
+    if (node.type === 'slab') {
+      this.getSlabMap(levelId).set(node.id, node as SlabNode)
+    } else if (node.type === 'wall') {
       const wall = node as WallNode
       this.walls.set(wall.id, wall)
     } else if (node.type === 'item') {
@@ -120,7 +150,9 @@ export class SpatialGridManager {
   }
 
   handleNodeDeleted(nodeId: string, nodeType: string, levelId: string) {
-    if (nodeType === 'wall') {
+    if (nodeType === 'slab') {
+      this.getSlabMap(levelId).delete(nodeId)
+    } else if (nodeType === 'wall') {
       this.walls.delete(nodeId)
       // Remove all items attached to this wall from the spatial grid
       const removedItemIds = this.getWallGrid(levelId).removeWall(nodeId)
@@ -191,15 +223,37 @@ export class SpatialGridManager {
     return this.getWallGrid(levelId).getWallForItem(itemId)
   }
 
+  /**
+   * Get the total slab elevation at a given (x, z) position on a level.
+   * Returns the highest slab elevation if the point is inside any slab polygon, otherwise 0.
+   */
+  getSlabElevationAt(levelId: string, x: number, z: number): number {
+    const slabMap = this.slabsByLevel.get(levelId)
+    if (!slabMap) return 0
+
+    let maxElevation = 0
+    for (const slab of slabMap.values()) {
+      if (slab.polygon.length >= 3 && pointInPolygon(x, z, slab.polygon)) {
+        const elevation = slab.elevation ?? 0.05
+        if (elevation > maxElevation) {
+          maxElevation = elevation
+        }
+      }
+    }
+    return maxElevation
+  }
+
   clearLevel(levelId: string) {
     this.floorGrids.delete(levelId)
     this.wallGrids.delete(levelId)
+    this.slabsByLevel.delete(levelId)
   }
 
   clear() {
     this.floorGrids.clear()
     this.wallGrids.clear()
     this.walls.clear()
+    this.slabsByLevel.clear()
   }
 }
 

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

@@ -53,10 +53,12 @@ export function initSpatialGridSync() {
       }
     }
 
-    // Detect updated nodes (items with position/rotation/parentId/side changes)
+    // Detect updated nodes (items with position/rotation/parentId/side changes, slabs with polygon/elevation changes)
     for (const [id, node] of Object.entries(state.nodes)) {
       const prev = prevState.nodes[id as AnyNode['id']]
-      if (prev && node.type === 'item' && prev.type === 'item') {
+      if (!prev) continue
+
+      if (node.type === 'item' && prev.type === 'item') {
         if (
           !arraysEqual(node.position, prev.position) ||
           !arraysEqual(node.rotation, prev.rotation) ||
@@ -66,6 +68,11 @@ export function initSpatialGridSync() {
           const levelId = resolveLevelId(node, state.nodes)
           spatialGridManager.handleNodeUpdated(node, levelId)
         }
+      } else if (node.type === 'slab' && prev.type === 'slab') {
+        if (node.polygon !== prev.polygon || node.elevation !== prev.elevation) {
+          const levelId = resolveLevelId(node, state.nodes)
+          spatialGridManager.handleNodeUpdated(node, levelId)
+        }
       }
     }
   })

packages/core/src/index.ts

@@ -29,6 +29,7 @@ export * from './schema'
 export { default as useScene } from './store/use-scene'
 // Systems
 export { CeilingSystem } from './systems/ceiling/ceiling-system'
+export { ItemSystem } from './systems/item/item-system'
 export { SlabSystem } from './systems/slab/slab-system'
 export { WallSystem } from './systems/wall/wall-system'
 

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

@@ -0,0 +1,46 @@
+import { useFrame } from '@react-three/fiber'
+import * as THREE from 'three'
+import { sceneRegistry } from '../../hooks/scene-registry/scene-registry'
+import { spatialGridManager } from '../../hooks/spatial-grid/spatial-grid-manager'
+import { resolveLevelId } from '../../hooks/spatial-grid/spatial-grid-sync'
+import type { AnyNodeId, ItemNode, WallNode } from '../../schema'
+import useScene from '../../store/use-scene'
+
+// ============================================================================
+// ITEM SYSTEM
+// ============================================================================
+
+export const ItemSystem = () => {
+  const { nodes, dirtyNodes, clearDirty } = useScene()
+
+  useFrame(() => {
+    if (dirtyNodes.size === 0) return
+
+    dirtyNodes.forEach((id) => {
+      const node = nodes[id]
+      if (!node || node.type !== 'item') return
+
+      const item = node as ItemNode
+      const mesh = sceneRegistry.nodes.get(id) as THREE.Object3D
+      if (!mesh) return
+
+      if (item.asset.attachTo === 'wall' || item.asset.attachTo === 'wall-side') {
+        // Wall-attached item: offset Z by half the parent wall's thickness
+        const parentWall = item.parentId ? nodes[item.parentId as AnyNodeId] : undefined
+        if (parentWall && parentWall.type === 'wall') {
+          const wallThickness = (parentWall as WallNode).thickness ?? 0.1
+          mesh.position.z = wallThickness / 2
+        }
+      } else if (!item.asset.attachTo) {
+        // Floor item: elevate by slab height
+        const levelId = resolveLevelId(item, nodes)
+        const slabElevation = spatialGridManager.getSlabElevationAt(levelId, item.position[0], item.position[2])
+        mesh.position.y = slabElevation
+      }
+
+      clearDirty(id as AnyNodeId)
+    })
+  })
+
+  return null
+}