Add two-sided wall material targeting

packages/core/src/events/bus.ts

@@ -38,6 +38,8 @@ export interface NodeEvent<T extends AnyNode = AnyNode> {
   position: [number, number, number]
   localPosition: [number, number, number]
   normal?: [number, number, number]
+  faceIndex?: number
+  materialIndex?: number
   stopPropagation: () => void
   nativeEvent: ThreeEvent<PointerEvent>
 }

packages/core/src/schema/index.ts

@@ -4,6 +4,13 @@ export { BaseNode, generateId, Material, nodeType, objectId } from './base'
 export { CameraSchema } from './camera'
 // Collections
 export { type Collection, type CollectionId, generateCollectionId } from './collections'
+export type {
+  MaterialMapProperties,
+  MaterialMaps,
+  MaterialPresetPayload,
+  MaterialTarget as MaterialTargetValue,
+  TextureWrapMode as TextureWrapModeValue,
+} from './material'
 // Material
 export {
   DEFAULT_MATERIALS,
@@ -14,15 +21,8 @@ export {
   MaterialProperties,
   MaterialSchema,
   MaterialTarget,
-  TextureWrapMode,
   resolveMaterial,
-} from './material'
+  TextureWrapMode,
-export type {
-  MaterialMapProperties,
-  MaterialMaps,
-  MaterialPresetPayload,
-  MaterialTarget as MaterialTargetValue,
-  TextureWrapMode as TextureWrapModeValue,
 } from './material'
 export { BuildingNode } from './nodes/building'
 export { CeilingNode } from './nodes/ceiling'
@@ -58,7 +58,12 @@ export {
 } from './nodes/stair'
 export { AttachmentSide, StairSegmentNode, StairSegmentType } from './nodes/stair-segment'
 export { SurfaceHoleMetadata } from './nodes/surface-hole-metadata'
-export { WallNode } from './nodes/wall'
+export type { WallSurfaceMaterialSpec, WallSurfaceSide } from './nodes/wall'
+export {
+  getEffectiveWallSurfaceMaterial,
+  getWallSurfaceMaterialSignature,
+  WallNode,
+} from './nodes/wall'
 export { WindowNode } from './nodes/window'
 export { ZoneNode } from './nodes/zone'
 export type { AnyNodeId, AnyNodeType } from './types'

packages/core/src/schema/nodes/wall.ts

@@ -12,8 +12,14 @@ export const WallNode = BaseNode.extend({
   children: z
     .array(z.union([ItemNode.shape.id, DoorNode.shape.id, WindowNode.shape.id]))
     .default([]),
+  // Legacy single-material wall finish. Read for backward compatibility only.
   material: MaterialSchema.optional(),
+  // Legacy single-material wall finish preset. Read for backward compatibility only.
   materialPreset: z.string().optional(),
+  interiorMaterial: MaterialSchema.optional(),
+  interiorMaterialPreset: z.string().optional(),
+  exteriorMaterial: MaterialSchema.optional(),
+  exteriorMaterialPreset: z.string().optional(),
   thickness: z.number().optional(),
   height: z.number().optional(),
   curveOffset: z.number().optional(),
@@ -37,3 +43,62 @@ export const WallNode = BaseNode.extend({
   `,
 )
 export type WallNode = z.infer<typeof WallNode>
+
+export type WallSurfaceSide = 'interior' | 'exterior'
+
+export type WallSurfaceMaterialSpec = {
+  material?: z.infer<typeof MaterialSchema>
+  materialPreset?: string
+}
+
+type WallSurfaceMaterialSource = {
+  material?: z.infer<typeof MaterialSchema>
+  materialPreset?: string
+  interiorMaterial?: z.infer<typeof MaterialSchema>
+  interiorMaterialPreset?: string
+  exteriorMaterial?: z.infer<typeof MaterialSchema>
+  exteriorMaterialPreset?: string
+}
+
+function getConfiguredWallSurfaceMaterial(
+  wall: WallSurfaceMaterialSource,
+  side: WallSurfaceSide,
+): WallSurfaceMaterialSpec {
+  if (side === 'interior') {
+    return {
+      material: wall.interiorMaterial,
+      materialPreset: wall.interiorMaterialPreset,
+    }
+  }
+
+  return {
+    material: wall.exteriorMaterial,
+    materialPreset: wall.exteriorMaterialPreset,
+  }
+}
+
+function hasSurfaceMaterial(spec: WallSurfaceMaterialSpec): boolean {
+  return spec.material !== undefined || typeof spec.materialPreset === 'string'
+}
+
+export function getEffectiveWallSurfaceMaterial(
+  wall: WallSurfaceMaterialSource,
+  side: WallSurfaceSide,
+): WallSurfaceMaterialSpec {
+  const configured = getConfiguredWallSurfaceMaterial(wall, side)
+  if (hasSurfaceMaterial(configured)) {
+    return configured
+  }
+
+  return {
+    material: wall.material,
+    materialPreset: wall.materialPreset,
+  }
+}
+
+export function getWallSurfaceMaterialSignature(spec: WallSurfaceMaterialSpec): string {
+  return JSON.stringify({
+    material: spec.material ?? null,
+    materialPreset: spec.materialPreset ?? null,
+  })
+}

packages/core/src/store/actions/node-actions.ts

@@ -1,4 +1,10 @@
-import type { AnyNode, AnyNodeId, WallNode } from '../../schema'
+import {
+  type AnyNode,
+  type AnyNodeId,
+  getEffectiveWallSurfaceMaterial,
+  getWallSurfaceMaterialSignature,
+  type WallNode,
+} from '../../schema'
 import type { CollectionId } from '../../schema/collections'
 import type { SceneState } from '../use-scene'
 
@@ -17,11 +23,7 @@ type WallMergePlan = {
 let pendingRafId: number | null = null
 let pendingUpdates: Set<AnyNodeId> = new Set()
 
-function pointsEqual(
+function pointsEqual(a: [number, number], b: [number, number], tolerance = 1e-6) {
-  a: [number, number],
-  b: [number, number],
-  tolerance = 1e-6,
-) {
   const dx = a[0] - b[0]
   const dz = a[1] - b[1]
   return dx * dx + dz * dz <= tolerance * tolerance
@@ -40,32 +42,30 @@ function getWallEndpointAtPoint(
   return null
 }
 
-function getWallFreeEndpoint(
+function getWallFreeEndpoint(wall: Pick<WallNode, 'start' | 'end'>, sharedPoint: [number, number]) {
-  wall: Pick<WallNode, 'start' | 'end'>,
-  sharedPoint: [number, number],
-) {
   return pointsEqual(wall.start, sharedPoint) ? wall.end : wall.start
 }
 
 function areWallStylesCompatible(a: WallNode, b: WallNode) {
+  const aInterior = getWallSurfaceMaterialSignature(getEffectiveWallSurfaceMaterial(a, 'interior'))
+  const bInterior = getWallSurfaceMaterialSignature(getEffectiveWallSurfaceMaterial(b, 'interior'))
+  const aExterior = getWallSurfaceMaterialSignature(getEffectiveWallSurfaceMaterial(a, 'exterior'))
+  const bExterior = getWallSurfaceMaterialSignature(getEffectiveWallSurfaceMaterial(b, 'exterior'))
+
   return (
     (a.parentId ?? null) === (b.parentId ?? null) &&
     Math.abs((a.curveOffset ?? 0) - (b.curveOffset ?? 0)) <= 1e-6 &&
     Math.abs((a.thickness ?? 0.2) - (b.thickness ?? 0.2)) <= 1e-6 &&
     Math.abs((a.height ?? 2.5) - (b.height ?? 2.5)) <= 1e-6 &&
-    a.materialPreset === b.materialPreset &&
+    aInterior === bInterior &&
-    JSON.stringify(a.material ?? null) === JSON.stringify(b.material ?? null) &&
+    aExterior === bExterior &&
     a.frontSide === b.frontSide &&
     a.backSide === b.backSide &&
     a.visible === b.visible
   )
 }
 
-function areWallsCollinearAcrossPoint(
+function areWallsCollinearAcrossPoint(a: WallNode, b: WallNode, sharedPoint: [number, number]) {
-  a: WallNode,
-  b: WallNode,
-  sharedPoint: [number, number],
-) {
   const freeA = getWallFreeEndpoint(a, sharedPoint)
   const freeB = getWallFreeEndpoint(b, sharedPoint)
   const ax = freeA[0] - sharedPoint[0]
@@ -111,7 +111,10 @@ function buildMergedWallAttachmentUpdates(
   mergedEnd: [number, number],
   nodes: Record<AnyNodeId, AnyNode>,
 ): WallAttachmentUpdate[] {
-  const mergedLength = Math.max(Math.hypot(mergedEnd[0] - mergedStart[0], mergedEnd[1] - mergedStart[1]), 1e-6)
+  const mergedLength = Math.max(
+    Math.hypot(mergedEnd[0] - mergedStart[0], mergedEnd[1] - mergedStart[1]),
+    1e-6,
+  )
   const tangentX = (mergedEnd[0] - mergedStart[0]) / mergedLength
   const tangentZ = (mergedEnd[1] - mergedStart[1]) / mergedLength
   const updates: WallAttachmentUpdate[] = []
@@ -126,11 +129,16 @@ function buildMergedWallAttachmentUpdates(
     const sourceWall = child.parentId === secondary.id ? secondary : primary
     const sourceLength = Math.max(wallLength(sourceWall), 1e-6)
     const localX = typeof child.position[0] === 'number' ? child.position[0] : 0
-    const worldX = sourceWall.start[0] + ((sourceWall.end[0] - sourceWall.start[0]) * localX) / sourceLength
+    const worldX =
-    const worldZ = sourceWall.start[1] + ((sourceWall.end[1] - sourceWall.start[1]) * localX) / sourceLength
+      sourceWall.start[0] + ((sourceWall.end[0] - sourceWall.start[0]) * localX) / sourceLength
+    const worldZ =
+      sourceWall.start[1] + ((sourceWall.end[1] - sourceWall.start[1]) * localX) / sourceLength
     const nextLocalX = Math.max(
       0,
-      Math.min(mergedLength, (worldX - mergedStart[0]) * tangentX + (worldZ - mergedStart[1]) * tangentZ),
+      Math.min(
+        mergedLength,
+        (worldX - mergedStart[0]) * tangentX + (worldZ - mergedStart[1]) * tangentZ,
+      ),
     )
 
     updates.push({

packages/core/src/store/use-scene.ts

@@ -100,6 +100,49 @@ function normalizeStairSegmentNode(node: Record<string, unknown>) {
   return parsed.success ? parsed.data : null
 }
 
+function migrateWallSurfaceMaterials(node: Record<string, any>) {
+  const hasInterior =
+    node.interiorMaterial !== undefined || typeof node.interiorMaterialPreset === 'string'
+  const hasExterior =
+    node.exteriorMaterial !== undefined || typeof node.exteriorMaterialPreset === 'string'
+  const legacyFinish = {
+    material: node.material,
+    materialPreset: typeof node.materialPreset === 'string' ? node.materialPreset : undefined,
+  }
+
+  if (!hasInterior && !hasExterior) {
+    if (legacyFinish.material === undefined && legacyFinish.materialPreset === undefined) {
+      return node
+    }
+
+    return {
+      ...node,
+      interiorMaterial: legacyFinish.material,
+      interiorMaterialPreset: legacyFinish.materialPreset,
+      exteriorMaterial: legacyFinish.material,
+      exteriorMaterialPreset: legacyFinish.materialPreset,
+    }
+  }
+
+  if (!hasInterior) {
+    return {
+      ...node,
+      interiorMaterial: node.exteriorMaterial,
+      interiorMaterialPreset: node.exteriorMaterialPreset,
+    }
+  }
+
+  if (!hasExterior) {
+    return {
+      ...node,
+      exteriorMaterial: node.interiorMaterial,
+      exteriorMaterialPreset: node.interiorMaterialPreset,
+    }
+  }
+
+  return node
+}
+
 function migrateNodes(nodes: Record<string, any>): Record<string, AnyNode> {
   const patchedNodes = { ...nodes }
   for (const [id, node] of Object.entries(patchedNodes)) {
@@ -153,6 +196,10 @@ function migrateNodes(nodes: Record<string, any>): Record<string, AnyNode> {
         patchedNodes[id] = normalized
       }
     }
+
+    if (node.type === 'wall') {
+      patchedNodes[id] = migrateWallSurfaceMaterials(patchedNodes[id])
+    }
   }
   return patchedNodes as Record<string, AnyNode>
 }

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

@@ -7,20 +7,30 @@ import { spatialGridManager } from '../../hooks/spatial-grid/spatial-grid-manage
 import { resolveLevelId } from '../../hooks/spatial-grid/spatial-grid-sync'
 import type { AnyNode, AnyNodeId, WallNode } from '../../schema'
 import useScene from '../../store/use-scene'
-import { DEFAULT_WALL_HEIGHT, getWallPlanFootprint, getWallThickness } from './wall-footprint'
 import { getWallCurveFrameAt, getWallSurfacePolygon, isCurvedWall } from './wall-curve'
+import { DEFAULT_WALL_HEIGHT, getWallPlanFootprint, getWallThickness } from './wall-footprint'
 import {
   calculateLevelMiters,
   getAdjacentWallIds,
   getWallMiterBoundaryPoints,
   type Point2D,
-  type WallMiterData,
   pointToKey,
+  type WallMiterData,
 } from './wall-mitering'
 
 // Reusable CSG evaluator for better performance
 const csgEvaluator = new Evaluator()
 const CURVED_WALL_3D_ENDPOINT_INSET = 0.0015
+const WALL_FACE_NORMAL_Y_EPSILON = 0.6
+const WALL_FACE_EDGE_DISTANCE_EPSILON = 0.003
+
+type WallBoundaryEdgeTag = 'front' | 'back' | 'base'
+
+type TaggedWallBoundaryEdge = {
+  start: THREE.Vector2
+  end: THREE.Vector2
+  tag: WallBoundaryEdgeTag
+}
 
 function ensureUv2Attribute(geometry: THREE.BufferGeometry) {
   const uv = geometry.getAttribute('uv')
@@ -78,6 +88,207 @@ function insetCurvedWallBoundaryPointsFor3D(
   return next
 }
 
+function addTaggedWallBoundaryEdge(
+  edges: TaggedWallBoundaryEdge[],
+  points: { x: number; z: number }[],
+  startIndex: number,
+  endIndex: number,
+  tag: WallBoundaryEdgeTag,
+) {
+  const start = points[startIndex]
+  const end = points[endIndex]
+  if (!(start && end)) return
+  if (Math.hypot(end.x - start.x, end.z - start.z) < 1e-6) return
+
+  edges.push({
+    start: new THREE.Vector2(start.x, start.z),
+    end: new THREE.Vector2(end.x, end.z),
+    tag,
+  })
+}
+
+function buildTaggedWallBoundaryEdges(
+  wall: WallNode,
+  localPoints: { x: number; z: number }[],
+  miterData: WallMiterData,
+): TaggedWallBoundaryEdge[] {
+  if (localPoints.length < 2) return []
+
+  const edges: TaggedWallBoundaryEdge[] = []
+
+  if (isCurvedWall(wall)) {
+    const sidePointCount = Math.floor(localPoints.length / 2)
+    if (sidePointCount < 2) return edges
+
+    for (let index = 0; index < sidePointCount - 1; index += 1) {
+      addTaggedWallBoundaryEdge(edges, localPoints, index, index + 1, 'back')
+    }
+
+    addTaggedWallBoundaryEdge(edges, localPoints, sidePointCount - 1, sidePointCount, 'base')
+
+    for (let index = sidePointCount; index < localPoints.length - 1; index += 1) {
+      addTaggedWallBoundaryEdge(edges, localPoints, index, index + 1, 'front')
+    }
+
+    addTaggedWallBoundaryEdge(edges, localPoints, localPoints.length - 1, 0, 'base')
+    return edges
+  }
+
+  const startKey = pointToKey({ x: wall.start[0], y: wall.start[1] })
+  const startJunction = miterData.junctionData.get(startKey)?.get(wall.id)
+  const startLeftIndex = startJunction ? localPoints.length - 2 : localPoints.length - 1
+  const endLeftIndex = startJunction ? localPoints.length - 3 : localPoints.length - 2
+
+  addTaggedWallBoundaryEdge(edges, localPoints, 0, 1, 'back')
+
+  for (let index = 1; index < endLeftIndex; index += 1) {
+    addTaggedWallBoundaryEdge(edges, localPoints, index, index + 1, 'base')
+  }
+
+  addTaggedWallBoundaryEdge(edges, localPoints, endLeftIndex, startLeftIndex, 'front')
+
+  for (let index = startLeftIndex; index < localPoints.length - 1; index += 1) {
+    addTaggedWallBoundaryEdge(edges, localPoints, index, index + 1, 'base')
+  }
+
+  addTaggedWallBoundaryEdge(edges, localPoints, localPoints.length - 1, 0, 'base')
+
+  return edges
+}
+
+function distanceToWallBoundaryEdge(point: THREE.Vector2, edge: TaggedWallBoundaryEdge): number {
+  const edgeDx = edge.end.x - edge.start.x
+  const edgeDz = edge.end.y - edge.start.y
+  const pointDx = point.x - edge.start.x
+  const pointDz = point.y - edge.start.y
+  const edgeLengthSq = edgeDx * edgeDx + edgeDz * edgeDz
+
+  if (edgeLengthSq < 1e-12) {
+    return point.distanceTo(edge.start)
+  }
+
+  const t = THREE.MathUtils.clamp((pointDx * edgeDx + pointDz * edgeDz) / edgeLengthSq, 0, 1)
+  const closestX = edge.start.x + edgeDx * t
+  const closestZ = edge.start.y + edgeDz * t
+
+  return Math.hypot(point.x - closestX, point.y - closestZ)
+}
+
+function getWallFaceMaterialIndex(
+  wall: Pick<WallNode, 'frontSide' | 'backSide'>,
+  face: 'front' | 'back',
+): 0 | 1 | 2 {
+  const semantic = face === 'front' ? wall.frontSide : wall.backSide
+  const fallback = face === 'front' ? 1 : 2
+
+  if (semantic === 'interior') return 1
+  if (semantic === 'exterior') return 2
+  return fallback
+}
+
+function assignWallMaterialGroups(
+  geometry: THREE.BufferGeometry,
+  wall: WallNode,
+  boundaryEdges: TaggedWallBoundaryEdge[],
+) {
+  const position = geometry.getAttribute('position')
+  if (!position) return
+
+  const index = geometry.getIndex()
+  const triangleCount = index ? Math.floor(index.count / 3) : Math.floor(position.count / 3)
+  if (triangleCount === 0) {
+    geometry.clearGroups()
+    return
+  }
+
+  const triangleMaterials = new Array<number>(triangleCount).fill(0)
+  const a = new THREE.Vector3()
+  const b = new THREE.Vector3()
+  const c = new THREE.Vector3()
+  const ab = new THREE.Vector3()
+  const ac = new THREE.Vector3()
+  const normal = new THREE.Vector3()
+  const centroid = new THREE.Vector3()
+  const projectedCentroid = new THREE.Vector2()
+  const maxBoundaryDistance = Math.max(
+    getWallThickness(wall) * 0.02,
+    WALL_FACE_EDGE_DISTANCE_EPSILON,
+  )
+
+  for (let triangleIndex = 0; triangleIndex < triangleCount; triangleIndex += 1) {
+    const baseIndex = triangleIndex * 3
+    const ia = index ? index.getX(baseIndex) : baseIndex
+    const ib = index ? index.getX(baseIndex + 1) : baseIndex + 1
+    const ic = index ? index.getX(baseIndex + 2) : baseIndex + 2
+
+    a.fromBufferAttribute(position, ia)
+    b.fromBufferAttribute(position, ib)
+    c.fromBufferAttribute(position, ic)
+
+    ab.subVectors(b, a)
+    ac.subVectors(c, a)
+    normal.crossVectors(ab, ac)
+
+    if (normal.lengthSq() < 1e-12) {
+      triangleMaterials[triangleIndex] = 0
+      continue
+    }
+
+    normal.normalize()
+
+    if (Math.abs(normal.y) >= WALL_FACE_NORMAL_Y_EPSILON) {
+      triangleMaterials[triangleIndex] = 0
+      continue
+    }
+
+    centroid
+      .copy(a)
+      .add(b)
+      .add(c)
+      .multiplyScalar(1 / 3)
+    projectedCentroid.set(centroid.x, centroid.z)
+
+    let nearestTag: WallBoundaryEdgeTag | null = null
+    let nearestDistance = Number.POSITIVE_INFINITY
+
+    for (const edge of boundaryEdges) {
+      const distance = distanceToWallBoundaryEdge(projectedCentroid, edge)
+      if (distance < nearestDistance) {
+        nearestDistance = distance
+        nearestTag = edge.tag
+      }
+    }
+
+    if (!nearestTag || nearestDistance > maxBoundaryDistance) {
+      triangleMaterials[triangleIndex] = 0
+      continue
+    }
+
+    if (nearestTag === 'base') {
+      triangleMaterials[triangleIndex] = 0
+      continue
+    }
+
+    triangleMaterials[triangleIndex] = getWallFaceMaterialIndex(wall, nearestTag)
+  }
+
+  geometry.clearGroups()
+
+  let currentMaterial = triangleMaterials[0] ?? 0
+  let groupStart = 0
+
+  for (let triangleIndex = 1; triangleIndex < triangleCount; triangleIndex += 1) {
+    const materialIndex = triangleMaterials[triangleIndex] ?? 0
+    if (materialIndex === currentMaterial) continue
+
+    geometry.addGroup(groupStart * 3, (triangleIndex - groupStart) * 3, currentMaterial)
+    groupStart = triangleIndex
+    currentMaterial = materialIndex
+  }
+
+  geometry.addGroup(groupStart * 3, (triangleCount - groupStart) * 3, currentMaterial)
+}
+
 // ============================================================================
 // WALL SYSTEM
 // ============================================================================
@@ -252,6 +463,7 @@ export function generateExtrudedWall(
 
   // Convert polygon to local coordinates
   const localPoints = polyPoints.map(worldToLocal)
+  const boundaryEdges = buildTaggedWallBoundaryEdges(wallNode, localPoints, miterData)
 
   // Build THREE.js shape
   // Shape uses (x, y) where we map: shape.x = local.x, shape.y = -local.z
@@ -272,6 +484,7 @@ export function generateExtrudedWall(
   // Rotate so extrusion direction (Z) becomes height direction (Y)
   geometry.rotateX(-Math.PI / 2)
   geometry.computeVertexNormals()
+  assignWallMaterialGroups(geometry, wallNode, boundaryEdges)
   ensureUv2Attribute(geometry)
 
   // Apply CSG subtraction for cutouts (doors/windows)
@@ -307,6 +520,7 @@ export function generateExtrudedWall(
 
   const resultGeometry = resultBrush.geometry
   resultGeometry.computeVertexNormals()
+  assignWallMaterialGroups(resultGeometry, wallNode, boundaryEdges)
   ensureUv2Attribute(resultGeometry)
 
   return resultGeometry

packages/editor/src/components/editor/selection-manager.tsx

@@ -8,6 +8,8 @@ import {
   resolveLevelId,
   sceneRegistry,
   useScene,
+  type WallEvent,
+  type WallSurfaceSide,
 } from '@pascal-app/core'
 
 import { useViewer } from '@pascal-app/viewer'
@@ -68,6 +70,32 @@ export const resolveBuildingId = (
   return null
 }
 
+function resolveWallMaterialTarget(event: WallEvent): WallSurfaceSide | null {
+  if (event.materialIndex === 1) return 'interior'
+  if (event.materialIndex === 2) return 'exterior'
+
+  const normalZ = event.normal?.[2]
+  const localZ = event.localPosition[2]
+  const thickness = event.node.thickness ?? 0.1
+
+  if (
+    normalZ === undefined ||
+    Math.abs(normalZ) < 0.65 ||
+    Math.abs(localZ) < Math.max(thickness * 0.2, 0.01)
+  ) {
+    return null
+  }
+
+  const hitFace = localZ >= 0 ? 'front' : 'back'
+  const semantic = hitFace === 'front' ? event.node.frontSide : event.node.backSide
+
+  if (semantic === 'interior' || semantic === 'exterior') {
+    return semantic
+  }
+
+  return hitFace === 'front' ? 'interior' : 'exterior'
+}
+
 const HIGHLIGHT_PROFILES = {
   delete: {
     color: new Color('#dc2626'),
@@ -439,6 +467,23 @@ export const SelectionManager = () => {
 
         activeStrategy.handleSelect(nodeToSelect, event.nativeEvent, modifierKeysRef.current)
 
+        if (node.type === 'wall' && nodeToSelect.type === 'wall') {
+          const nextWallMaterialTarget = resolveWallMaterialTarget(event as WallEvent)
+          if (nextWallMaterialTarget) {
+            useEditor.getState().setSelectedWallMaterialTarget({
+              wallId: nodeToSelect.id,
+              side: nextWallMaterialTarget,
+            })
+          } else {
+            const currentWallMaterialTarget = useEditor.getState().selectedWallMaterialTarget
+            if (currentWallMaterialTarget?.wallId !== nodeToSelect.id) {
+              useEditor.getState().setSelectedWallMaterialTarget(null)
+            }
+          }
+        } else if (useEditor.getState().selectedWallMaterialTarget) {
+          useEditor.getState().setSelectedWallMaterialTarget(null)
+        }
+
         // Reset the handled flag after a short delay to allow grid:click to be ignored
         setTimeout(() => {
           clickHandledRef.current = false
@@ -471,6 +516,7 @@ export const SelectionManager = () => {
       const { phase, structureLayer } = useEditor.getState()
       const activeStrategy = SELECTION_STRATEGIES[phase]
       if (activeStrategy) activeStrategy.handleDeselect()
+      useEditor.getState().setSelectedWallMaterialTarget(null)
 
       // When deselecting from zone mode, return to structure select
       if (phase === 'structure' && structureLayer === 'zones') {
@@ -704,6 +750,12 @@ export const SelectionManager = () => {
 }
 
 const SelectionStateSync = () => {
+  const selectedWallMaterialTarget = useEditor((s) => s.selectedWallMaterialTarget)
+  const setSelectedWallMaterialTarget = useEditor((s) => s.setSelectedWallMaterialTarget)
+  const singleSelectedId = useViewer((s) =>
+    s.selection.selectedIds.length === 1 ? s.selection.selectedIds[0] : null,
+  )
+
   useEffect(() => {
     return useScene.subscribe((state) => {
       const { buildingId, levelId, zoneId, selectedIds } = useViewer.getState().selection
@@ -732,6 +784,25 @@ const SelectionStateSync = () => {
     })
   }, [])
 
+  useEffect(() => {
+    if (!selectedWallMaterialTarget) return
+
+    if (!singleSelectedId) {
+      setSelectedWallMaterialTarget(null)
+      return
+    }
+
+    const selectedNode = useScene.getState().nodes[singleSelectedId as AnyNodeId]
+    if (!(selectedNode?.type === 'wall')) {
+      setSelectedWallMaterialTarget(null)
+      return
+    }
+
+    if (selectedWallMaterialTarget.wallId !== selectedNode.id) {
+      setSelectedWallMaterialTarget(null)
+    }
+  }, [selectedWallMaterialTarget, setSelectedWallMaterialTarget, singleSelectedId])
+
   return null
 }
 

packages/editor/src/components/ui/controls/material-picker.tsx

@@ -6,7 +6,7 @@ import {
   type MaterialSchema,
   type MaterialTarget,
 } from '@pascal-app/core'
-import { useState } from 'react'
+import { useEffect, useState } from 'react'
 
 type MaterialPickerProps = {
   nodeType?: MaterialTarget
@@ -14,6 +14,7 @@ type MaterialPickerProps = {
   selectedMaterialPreset?: string
   onChange?: (material: MaterialSchema) => void
   onSelectMaterialPreset?: (materialPreset: string) => void
+  hideSideControl?: boolean
 }
 
 export function MaterialPicker({
@@ -22,10 +23,15 @@ export function MaterialPicker({
   selectedMaterialPreset,
   onChange,
   onSelectMaterialPreset,
+  hideSideControl = false,
 }: MaterialPickerProps) {
   const [showCustom, setShowCustom] = useState<boolean>(!!value?.properties)
   const catalogItems = nodeType ? getMaterialsForTarget(nodeType) : []
 
+  useEffect(() => {
+    setShowCustom(!!value?.properties && !selectedMaterialPreset)
+  }, [selectedMaterialPreset, value?.properties])
+
   const currentProps = value?.properties || {
     color: '#ffffff',
     roughness: 0.5,
@@ -193,6 +199,7 @@ export function MaterialPicker({
             </span>
           </div>
 
+          {!hideSideControl && (
             <div className="flex items-center gap-2">
               <label className="w-16 text-gray-500 text-xs">Side</label>
               <select
@@ -207,6 +214,7 @@ export function MaterialPicker({
                 <option value="double">Double</option>
               </select>
             </div>
+          )}
         </div>
       )}
     </div>

packages/editor/src/components/ui/panels/wall-panel.tsx

@@ -3,17 +3,20 @@
 import {
   type AnyNode,
   type AnyNodeId,
+  getEffectiveWallSurfaceMaterial,
   getClampedWallCurveOffset,
   getMaxWallCurveOffset,
   getWallCurveLength,
+  getWallSurfaceMaterialSignature,
   normalizeWallCurveOffset,
   type MaterialSchema,
   useScene,
+  type WallSurfaceSide,
   type WallNode,
 } from '@pascal-app/core'
 import { useViewer } from '@pascal-app/viewer'
 import { Move, Spline } from 'lucide-react'
-import { useCallback } from 'react'
+import { useCallback, useMemo } from 'react'
 import { sfxEmitter } from '../../../lib/sfx-bus'
 import useEditor from '../../../store/use-editor'
 import { ActionButton, ActionGroup } from '../controls/action-button'
@@ -22,12 +25,39 @@ import { PanelSection } from '../controls/panel-section'
 import { SliderControl } from '../controls/slider-control'
 import { PanelWrapper } from './panel-wrapper'
 
+function buildWallSurfaceMaterialPatch(
+  node: WallNode,
+  targetSide: WallSurfaceSide | null,
+  material: MaterialSchema | undefined,
+  materialPreset: string | undefined,
+): Partial<WallNode> {
+  const nextSurfaceMaterial = { material, materialPreset }
+  const nextInterior =
+    targetSide === null || targetSide === 'interior'
+      ? nextSurfaceMaterial
+      : getEffectiveWallSurfaceMaterial(node, 'interior')
+  const nextExterior =
+    targetSide === null || targetSide === 'exterior'
+      ? nextSurfaceMaterial
+      : getEffectiveWallSurfaceMaterial(node, 'exterior')
+
+  return {
+    interiorMaterial: nextInterior.material,
+    interiorMaterialPreset: nextInterior.materialPreset,
+    exteriorMaterial: nextExterior.material,
+    exteriorMaterialPreset: nextExterior.materialPreset,
+    material: undefined,
+    materialPreset: undefined,
+  }
+}
+
 export function WallPanel() {
   const selectedId = useViewer((s) => s.selection.selectedIds[0])
   const setSelection = useViewer((s) => s.setSelection)
   const updateNode = useScene((s) => s.updateNode)
   const setMovingNode = useEditor((s) => s.setMovingNode)
   const setCurvingWall = useEditor((s) => s.setCurvingWall)
+  const selectedWallMaterialTarget = useEditor((s) => s.selectedWallMaterialTarget)
 
   const node = useScene((s) =>
     selectedId ? (s.nodes[selectedId as AnyNode['id']] as WallNode | undefined) : undefined,
@@ -58,6 +88,33 @@ export function WallPanel() {
     [selectedId, updateNode],
   )
 
+  const effectiveInteriorMaterial = useMemo(
+    () => (node ? getEffectiveWallSurfaceMaterial(node, 'interior') : {}),
+    [node],
+  )
+  const effectiveExteriorMaterial = useMemo(
+    () => (node ? getEffectiveWallSurfaceMaterial(node, 'exterior') : {}),
+    [node],
+  )
+  const surfaceMaterialsMatch = useMemo(
+    () =>
+      getWallSurfaceMaterialSignature(effectiveInteriorMaterial) ===
+      getWallSurfaceMaterialSignature(effectiveExteriorMaterial),
+    [effectiveExteriorMaterial, effectiveInteriorMaterial],
+  )
+  const materialTargetSide =
+    selectedWallMaterialTarget && selectedWallMaterialTarget.wallId === node?.id
+      ? selectedWallMaterialTarget.side
+      : null
+  const materialPickerValue =
+    materialTargetSide === 'interior'
+      ? effectiveInteriorMaterial
+      : materialTargetSide === 'exterior'
+        ? effectiveExteriorMaterial
+        : surfaceMaterialsMatch
+          ? effectiveInteriorMaterial
+          : {}
+
   const handleUpdateLength = useCallback(
     (newLength: number) => {
       if (!node || newLength <= 0) return
@@ -83,16 +140,18 @@ export function WallPanel() {
 
   const handleMaterialPresetChange = useCallback(
     (materialPreset: string) => {
-      handleUpdate({ materialPreset, material: undefined })
+      if (!node || !materialTargetSide) return
+      handleUpdate(buildWallSurfaceMaterialPatch(node, materialTargetSide, undefined, materialPreset))
     },
-    [handleUpdate],
+    [handleUpdate, materialTargetSide, node],
   )
 
   const handleCustomMaterialChange = useCallback(
     (material: MaterialSchema) => {
-      handleUpdate({ material, materialPreset: undefined })
+      if (!node || !materialTargetSide) return
+      handleUpdate(buildWallSurfaceMaterialPatch(node, materialTargetSide, material, undefined))
     },
-    [handleUpdate],
+    [handleUpdate, materialTargetSide, node],
   )
 
   const handleClose = useCallback(() => {
@@ -177,15 +236,24 @@ export function WallPanel() {
       </PanelSection>
 
       <PanelSection title="Material">
+        {!materialTargetSide ? (
+          <div className="mb-3 rounded-lg border border-border/50 bg-[#2C2C2E] px-3 py-2 text-[11px] text-muted-foreground">
+            Click the wall face you want to edit. Materials now apply to one side at a time.
+          </div>
+        ) : null}
+        {materialTargetSide ? (
           <MaterialPicker
+            hideSideControl
             nodeType="wall"
             onChange={handleCustomMaterialChange}
             onSelectMaterialPreset={handleMaterialPresetChange}
-          selectedMaterialPreset={node.materialPreset}
+            selectedMaterialPreset={materialPickerValue.materialPreset}
-          value={node.material}
+            value={materialPickerValue.material}
           />
+        ) : null}
       </PanelSection>
 
+      <PanelSection title="Actions">
         <ActionGroup>
           <ActionButton icon={<Move className="h-3.5 w-3.5" />} label="Move" onClick={handleMove} />
           {!hasWallChildrenBlockingCurve && (
@@ -196,6 +264,7 @@ export function WallPanel() {
             />
           )}
         </ActionGroup>
+      </PanelSection>
     </PanelWrapper>
   )
 }

packages/editor/src/store/use-editor.tsx

@@ -16,6 +16,7 @@ import {
   type StairSegmentNode,
   useScene,
   type WallNode,
+  type WallSurfaceSide,
   type WindowNode,
 } from '@pascal-app/core'
 import { useViewer } from '@pascal-app/viewer'
@@ -80,6 +81,11 @@ export type MovingWallEndpoint = {
   endpoint: 'start' | 'end'
 }
 
+export type SelectedWallMaterialTarget = {
+  wallId: WallNode['id']
+  side: WallSurfaceSide
+}
+
 type EditorState = {
   phase: Phase
   setPhase: (phase: Phase) => void
@@ -127,6 +133,8 @@ type EditorState = {
   setMovingWallEndpoint: (value: MovingWallEndpoint | null) => void
   curvingWall: WallNode | null
   setCurvingWall: (wall: WallNode | null) => void
+  selectedWallMaterialTarget: SelectedWallMaterialTarget | null
+  setSelectedWallMaterialTarget: (target: SelectedWallMaterialTarget | null) => void
   selectedReferenceId: string | null
   setSelectedReferenceId: (id: string | null) => void
   // Space detection for cutaway mode
@@ -502,6 +510,8 @@ const useEditor = create<EditorState>()(
       setMovingWallEndpoint: (value) => set({ movingWallEndpoint: value }),
       curvingWall: null,
       setCurvingWall: (wall) => set({ curvingWall: wall }),
+      selectedWallMaterialTarget: null,
+      setSelectedWallMaterialTarget: (target) => set({ selectedWallMaterialTarget: target }),
       selectedReferenceId: null,
       setSelectedReferenceId: (id) => set({ selectedReferenceId: id }),
       spaces: {},

packages/viewer/src/components/renderers/wall/wall-renderer.tsx

@@ -1,12 +1,8 @@
 import { useRegistry, useScene, type WallNode } from '@pascal-app/core'
-import { useLayoutEffect, useMemo, useRef } from 'react'
+import { useLayoutEffect, useRef } from 'react'
 import type { Mesh } from 'three'
 import { useNodeEvents } from '../../../hooks/use-node-events'
-import {
+import { getVisibleWallMaterials } from '../../../systems/wall/wall-materials'
-  createMaterial,
-  createMaterialFromPresetRef,
-  DEFAULT_WALL_MATERIAL,
-} from '../../../lib/materials'
 import { NodeRenderer } from '../node-renderer'
 
 export const WallRenderer = ({ node }: { node: WallNode }) => {
@@ -19,20 +15,7 @@ export const WallRenderer = ({ node }: { node: WallNode }) => {
   }, [node.id])
 
   const handlers = useNodeEvents(node, 'wall')
-
+  const material = getVisibleWallMaterials(node)
-  const material = useMemo(() => {
-    const presetMaterial = createMaterialFromPresetRef(node.materialPreset)
-    if (presetMaterial) return presetMaterial
-    const mat = node.material
-    if (!mat) return DEFAULT_WALL_MATERIAL
-    return createMaterial(mat)
-  }, [
-    node.material,
-    node.material?.preset,
-    node.material?.properties,
-    node.material?.texture,
-    node.materialPreset,
-  ])
 
   return (
     <mesh castShadow material={material} receiveShadow ref={ref} visible={node.visible}>

packages/viewer/src/hooks/use-node-events.ts

@@ -33,6 +33,7 @@ import {
   type ZoneNode,
 } from '@pascal-app/core'
 import type { ThreeEvent } from '@react-three/fiber'
+import type { BufferGeometry, Mesh } from 'three'
 import useViewer from '../store/use-viewer'
 
 type NodeConfig = {
@@ -55,6 +56,23 @@ type NodeConfig = {
 
 type NodeType = keyof NodeConfig
 
+function getIntersectionMaterialIndex(
+  object: ThreeEvent<PointerEvent>['object'],
+  faceIndex: number | undefined,
+): number | undefined {
+  if (faceIndex === undefined) return undefined
+
+  const geometry = (object as Mesh).geometry as BufferGeometry | undefined
+  if (!geometry || geometry.groups.length === 0) return undefined
+
+  const triangleStart = faceIndex * 3
+  const group = geometry.groups.find(
+    (entry) => triangleStart >= entry.start && triangleStart < entry.start + entry.count,
+  )
+
+  return group?.materialIndex
+}
+
 export function useNodeEvents<T extends NodeType>(node: NodeConfig[T]['node'], type: T) {
   const emit = (suffix: EventSuffix, e: ThreeEvent<PointerEvent>) => {
     const eventKey = `${type}:${suffix}` as `${T}:${EventSuffix}`
@@ -64,6 +82,8 @@ export function useNodeEvents<T extends NodeType>(node: NodeConfig[T]['node'], t
       position: [e.point.x, e.point.y, e.point.z],
       localPosition: [localPoint.x, localPoint.y, localPoint.z],
       normal: e.face ? [e.face.normal.x, e.face.normal.y, e.face.normal.z] : undefined,
+      faceIndex: e.faceIndex ?? undefined,
+      materialIndex: getIntersectionMaterialIndex(e.object, e.faceIndex ?? undefined),
       stopPropagation: () => e.stopPropagation(),
       nativeEvent: e,
     } as NodeConfig[T]['event']

packages/viewer/src/systems/wall/wall-cutout.tsx

@@ -1,210 +1,14 @@
-import {
+import { type AnyNodeId, emitter, sceneRegistry, useScene, type WallNode } from '@pascal-app/core'
-  type AnyNodeId,
-  baseMaterial,
-  emitter,
-  getMaterialPresetByRef,
-  sceneRegistry,
-  useScene,
-  type WallNode,
-} from '@pascal-app/core'
 import { useFrame } from '@react-three/fiber'
 import { useEffect, useRef } from 'react'
 import type { Material } from 'three'
-import { Color } from 'three'
+import { type Mesh, Vector3 } from 'three/webgpu'
-import { Fn, float, fract, length, mix, positionLocal, smoothstep, step, vec2 } from 'three/tsl'
-import { type Mesh, MeshStandardNodeMaterial, Vector3 } from 'three/webgpu'
 import useViewer from '../../store/use-viewer'
-import { createMaterial, createMaterialFromPresetRef } from '../../lib/materials'
+import { getMaterialsForWall } from './wall-materials'
 
 const tmpVec = new Vector3()
 const u = new Vector3()
 const v = new Vector3()
-const DEFAULT_WALL_COLOR = '#f2f0ed'
-const WALL_HIGHLIGHT_PROFILES = {
-  delete: {
-    color: new Color('#dc2626'),
-    blend: 0.76,
-    emissiveBlend: 0.92,
-    emissiveIntensity: 0.46,
-  },
-  selection: {
-    color: new Color('#818cf8'),
-    blend: 0.32,
-    emissiveBlend: 0.7,
-    emissiveIntensity: 0.42,
-  },
-} as const
-
-type WallHighlightKind = keyof typeof WALL_HIGHLIGHT_PROFILES
-
-const dotPattern = Fn(() => {
-  const scale = float(0.1)
-  const dotSize = float(0.3)
-
-  const uv = vec2(positionLocal.x, positionLocal.y).div(scale)
-  const gridUV = fract(uv)
-
-  const dist = length(gridUV.sub(0.5))
-
-  const dots = step(dist, dotSize.mul(0.5))
-
-  const fadeHeight = float(2.5)
-  const yFade = float(1).sub(smoothstep(float(0), fadeHeight, positionLocal.y))
-
-  return dots.mul(yFade)
-})
-
-interface WallMaterials {
-  visible: Material
-  invisible: MeshStandardNodeMaterial
-  deleteVisible: Material
-  deleteInvisible: MeshStandardNodeMaterial
-  highlightedVisible: Material
-  highlightedInvisible: MeshStandardNodeMaterial
-  materialHash: string
-}
-
-const wallMaterialCache = new Map<string, WallMaterials>()
-
-const presetColors = {
-  white: '#ffffff',
-  brick: '#8b4513',
-  concrete: '#808080',
-  wood: '#deb887',
-  glass: '#87ceeb',
-  metal: '#c0c0c0',
-  plaster: '#f5f5dc',
-  tile: '#dcdcdc',
-  marble: '#f5f5f5',
-} as const
-
-function getMaterialHash(wallNode: WallNode): string {
-  if (wallNode.materialPreset) return `preset-ref-${wallNode.materialPreset}`
-  if (!wallNode.material) return 'none'
-  const mat = wallNode.material
-  if (mat.preset && mat.preset !== 'custom') {
-    return `preset-${mat.preset}`
-  }
-  if (mat.properties) {
-    return `props-${mat.properties.color}-${mat.properties.roughness}-${mat.properties.metalness}`
-  }
-  return 'default'
-}
-
-function getPresetColor(preset: string): string {
-  return presetColors[preset as keyof typeof presetColors] ?? '#ffffff'
-}
-
-function getHighlightedColor(color: Color, kind: WallHighlightKind): Color {
-  const profile = WALL_HIGHLIGHT_PROFILES[kind]
-  return color.clone().lerp(profile.color, profile.blend)
-}
-
-function createHighlightedWallMaterial(
-  material: Material,
-  kind: WallHighlightKind,
-): Material {
-  const highlightedMaterial = material.clone() as Material & {
-    color?: Color
-    emissive?: Color
-    emissiveIntensity?: number
-    needsUpdate?: boolean
-  }
-  const profile = WALL_HIGHLIGHT_PROFILES[kind]
-
-  if ('color' in highlightedMaterial && highlightedMaterial.color) {
-    highlightedMaterial.color = getHighlightedColor(highlightedMaterial.color, kind)
-  }
-  if ('emissive' in highlightedMaterial && highlightedMaterial.emissive) {
-    highlightedMaterial.emissive = highlightedMaterial.emissive
-      .clone()
-      .lerp(profile.color, profile.emissiveBlend)
-  }
-  if ('emissiveIntensity' in highlightedMaterial) {
-    highlightedMaterial.emissiveIntensity = Math.max(
-      highlightedMaterial.emissiveIntensity ?? 0,
-      profile.emissiveIntensity,
-    )
-  }
-  highlightedMaterial.needsUpdate = true
-
-  return highlightedMaterial
-}
-
-function createBaseVisibleWallMaterial(wallNode: WallNode): Material {
-  if (wallNode.materialPreset) {
-    return createMaterialFromPresetRef(wallNode.materialPreset) ?? baseMaterial
-  }
-
-  if (wallNode.material) {
-    return createMaterial(wallNode.material)
-  }
-
-  return baseMaterial
-}
-
-function getMaterialsForWall(wallNode: WallNode): WallMaterials {
-  const cacheKey = wallNode.id
-  const materialHash = getMaterialHash(wallNode)
-
-  const existing = wallMaterialCache.get(cacheKey)
-  if (existing && existing.materialHash === materialHash) {
-    return existing
-  }
-
-  if (existing) {
-    existing.visible.dispose()
-    existing.invisible.dispose()
-    existing.deleteVisible.dispose()
-    existing.deleteInvisible.dispose()
-    existing.highlightedVisible.dispose()
-    existing.highlightedInvisible.dispose()
-  }
-
-  let userColor = DEFAULT_WALL_COLOR
-  const preset = getMaterialPresetByRef(wallNode.materialPreset)
-  if (preset?.mapProperties?.color) {
-    userColor = preset.mapProperties.color
-  } else if (wallNode.material?.properties?.color) {
-    userColor = wallNode.material.properties.color
-  } else if (wallNode.material?.preset && wallNode.material.preset !== 'custom') {
-    userColor = getPresetColor(wallNode.material.preset)
-  }
-
-  const visibleMat = createBaseVisibleWallMaterial(wallNode)
-
-  const invisibleMat = new MeshStandardNodeMaterial({
-    transparent: true,
-    opacityNode: mix(float(0.0), float(0.24), dotPattern()),
-    color: userColor,
-    depthWrite: false,
-    emissive: userColor,
-  })
-
-  const highlightedVisible = createHighlightedWallMaterial(visibleMat, 'selection')
-  const highlightedInvisible = createHighlightedWallMaterial(
-    invisibleMat,
-    'selection',
-  ) as MeshStandardNodeMaterial
-  const deleteVisible = createHighlightedWallMaterial(visibleMat, 'delete')
-  const deleteInvisible = createHighlightedWallMaterial(invisibleMat, 'delete') as MeshStandardNodeMaterial
-
-  const result: WallMaterials = {
-    visible: visibleMat,
-    invisible: invisibleMat,
-    deleteVisible,
-    deleteInvisible,
-    highlightedVisible,
-    highlightedInvisible,
-    materialHash,
-  }
-  wallMaterialCache.set(cacheKey, result)
-  return result
-}
-
-function getVisibleWallMaterial(wallNode: WallNode): Material {
-  return createBaseVisibleWallMaterial(wallNode)
-}
 
 function getWallHideState(
   wallNode: WallNode,
@@ -301,7 +105,7 @@ export const WallCutout = () => {
             ? materials.deleteVisible
             : isSelectionHighlighted
               ? materials.highlightedVisible
-              : getVisibleWallMaterial(wallNode)
+              : materials.visible
         }
       })
       lastWallMode.current = wallMode
@@ -311,7 +115,7 @@ export const WallCutout = () => {
   })
 
   useEffect(() => {
-    const snapshot = new Map<Mesh, Material>()
+    const snapshot = new Map<Mesh, Material | Material[]>()
 
     const restoreForCapture = () => {
       sceneRegistry.byType.wall.forEach((wallId) => {
@@ -320,10 +124,10 @@ export const WallCutout = () => {
         const wallNode = useScene.getState().nodes[wallId as AnyNodeId] as WallNode | undefined
         if (!wallNode || wallNode.type !== 'wall') return
         const mats = getMaterialsForWall(wallNode)
-        const current = wallMesh.material as Material
+        const current = wallMesh.material as Material | Material[]
         snapshot.set(wallMesh, current)
         if (current === mats.highlightedVisible || current === mats.deleteVisible) {
-          wallMesh.material = getVisibleWallMaterial(wallNode)
+          wallMesh.material = mats.visible
         } else if (current === mats.highlightedInvisible || current === mats.deleteInvisible) {
           wallMesh.material = mats.invisible
         }

packages/viewer/src/systems/wall/wall-materials.ts

@@ -0,0 +1,226 @@
+import {
+  baseMaterial,
+  getEffectiveWallSurfaceMaterial,
+  getMaterialPresetByRef,
+  getWallSurfaceMaterialSignature,
+  resolveMaterial,
+  type WallNode,
+  type WallSurfaceMaterialSpec,
+} from '@pascal-app/core'
+import { Color, type Material } from 'three'
+import { Fn, float, fract, length, mix, positionLocal, smoothstep, step, vec2 } from 'three/tsl'
+import { MeshStandardNodeMaterial } from 'three/webgpu'
+import { createMaterial, createMaterialFromPresetRef } from '../../lib/materials'
+
+const DEFAULT_WALL_COLOR = '#f2f0ed'
+
+const WALL_HIGHLIGHT_PROFILES = {
+  delete: {
+    color: new Color('#dc2626'),
+    blend: 0.76,
+    emissiveBlend: 0.92,
+    emissiveIntensity: 0.46,
+  },
+  selection: {
+    color: new Color('#818cf8'),
+    blend: 0.32,
+    emissiveBlend: 0.7,
+    emissiveIntensity: 0.42,
+  },
+} as const
+
+type WallHighlightKind = keyof typeof WALL_HIGHLIGHT_PROFILES
+
+export type WallMaterialArray = [Material, Material, Material]
+
+export interface WallMaterials {
+  visible: WallMaterialArray
+  invisible: WallMaterialArray
+  deleteVisible: WallMaterialArray
+  deleteInvisible: WallMaterialArray
+  highlightedVisible: WallMaterialArray
+  highlightedInvisible: WallMaterialArray
+  materialHash: string
+}
+
+const wallMaterialCache = new Map<string, WallMaterials>()
+
+const dotPattern = Fn(() => {
+  const scale = float(0.1)
+  const dotSize = float(0.3)
+
+  const uv = vec2(positionLocal.x, positionLocal.y).div(scale)
+  const gridUV = fract(uv)
+
+  const dist = length(gridUV.sub(0.5))
+
+  const dots = step(dist, dotSize.mul(0.5))
+
+  const fadeHeight = float(2.5)
+  const yFade = float(1).sub(smoothstep(float(0), fadeHeight, positionLocal.y))
+
+  return dots.mul(yFade)
+})
+
+function getSurfaceVisibleMaterial(spec: WallSurfaceMaterialSpec): Material {
+  if (spec.materialPreset) {
+    return createMaterialFromPresetRef(spec.materialPreset) ?? baseMaterial
+  }
+
+  if (spec.material) {
+    return createMaterial(spec.material)
+  }
+
+  return baseMaterial
+}
+
+function getSurfaceColor(spec: WallSurfaceMaterialSpec, fallback = DEFAULT_WALL_COLOR): string {
+  const preset = getMaterialPresetByRef(spec.materialPreset)
+  if (preset?.mapProperties?.color) {
+    return preset.mapProperties.color
+  }
+
+  if (spec.material) {
+    return resolveMaterial(spec.material).color
+  }
+
+  return fallback
+}
+
+function getHighlightedColor(color: Color, kind: WallHighlightKind): Color {
+  const profile = WALL_HIGHLIGHT_PROFILES[kind]
+  return color.clone().lerp(profile.color, profile.blend)
+}
+
+function createHighlightedWallMaterial(material: Material, kind: WallHighlightKind): Material {
+  const highlightedMaterial = material.clone() as Material & {
+    color?: Color
+    emissive?: Color
+    emissiveIntensity?: number
+    needsUpdate?: boolean
+  }
+  const profile = WALL_HIGHLIGHT_PROFILES[kind]
+
+  if ('color' in highlightedMaterial && highlightedMaterial.color) {
+    highlightedMaterial.color = getHighlightedColor(highlightedMaterial.color, kind)
+  }
+  if ('emissive' in highlightedMaterial && highlightedMaterial.emissive) {
+    highlightedMaterial.emissive = highlightedMaterial.emissive
+      .clone()
+      .lerp(profile.color, profile.emissiveBlend)
+  }
+  if ('emissiveIntensity' in highlightedMaterial) {
+    highlightedMaterial.emissiveIntensity = Math.max(
+      highlightedMaterial.emissiveIntensity ?? 0,
+      profile.emissiveIntensity,
+    )
+  }
+  highlightedMaterial.needsUpdate = true
+
+  return highlightedMaterial
+}
+
+function createInvisibleWallMaterial(color: string): MeshStandardNodeMaterial {
+  return new MeshStandardNodeMaterial({
+    transparent: true,
+    opacityNode: mix(float(0.0), float(0.24), dotPattern()),
+    color,
+    depthWrite: false,
+    emissive: color,
+  })
+}
+
+function mapWallMaterialArray(
+  materials: WallMaterialArray,
+  iteratee: (material: Material, index: number) => Material,
+): WallMaterialArray {
+  return materials.map(iteratee) as WallMaterialArray
+}
+
+function disposeOwnedMaterials(materials: WallMaterialArray[]) {
+  const owned = new Set<Material>()
+  materials.forEach((entry) => {
+    entry.forEach((material) => {
+      owned.add(material)
+    })
+  })
+  owned.forEach((material) => {
+    material.dispose()
+  })
+}
+
+export function getWallMaterialHash(wallNode: WallNode): string {
+  return JSON.stringify({
+    interior: getWallSurfaceMaterialSignature(
+      getEffectiveWallSurfaceMaterial(wallNode, 'interior'),
+    ),
+    exterior: getWallSurfaceMaterialSignature(
+      getEffectiveWallSurfaceMaterial(wallNode, 'exterior'),
+    ),
+  })
+}
+
+export function getMaterialsForWall(wallNode: WallNode): WallMaterials {
+  const cacheKey = wallNode.id
+  const materialHash = getWallMaterialHash(wallNode)
+
+  const existing = wallMaterialCache.get(cacheKey)
+  if (existing && existing.materialHash === materialHash) {
+    return existing
+  }
+
+  if (existing) {
+    disposeOwnedMaterials([
+      existing.invisible,
+      existing.deleteVisible,
+      existing.deleteInvisible,
+      existing.highlightedVisible,
+      existing.highlightedInvisible,
+    ])
+  }
+
+  const interiorSpec = getEffectiveWallSurfaceMaterial(wallNode, 'interior')
+  const exteriorSpec = getEffectiveWallSurfaceMaterial(wallNode, 'exterior')
+
+  const visible: WallMaterialArray = [
+    baseMaterial,
+    getSurfaceVisibleMaterial(interiorSpec),
+    getSurfaceVisibleMaterial(exteriorSpec),
+  ]
+
+  const invisible: WallMaterialArray = [
+    createInvisibleWallMaterial(DEFAULT_WALL_COLOR),
+    createInvisibleWallMaterial(getSurfaceColor(interiorSpec, DEFAULT_WALL_COLOR)),
+    createInvisibleWallMaterial(getSurfaceColor(exteriorSpec, DEFAULT_WALL_COLOR)),
+  ]
+
+  const highlightedVisible = mapWallMaterialArray(visible, (material) =>
+    createHighlightedWallMaterial(material, 'selection'),
+  )
+  const highlightedInvisible = mapWallMaterialArray(invisible, (material) =>
+    createHighlightedWallMaterial(material, 'selection'),
+  )
+  const deleteVisible = mapWallMaterialArray(visible, (material) =>
+    createHighlightedWallMaterial(material, 'delete'),
+  )
+  const deleteInvisible = mapWallMaterialArray(invisible, (material) =>
+    createHighlightedWallMaterial(material, 'delete'),
+  )
+
+  const result: WallMaterials = {
+    visible,
+    invisible,
+    deleteVisible,
+    deleteInvisible,
+    highlightedVisible,
+    highlightedInvisible,
+    materialHash,
+  }
+
+  wallMaterialCache.set(cacheKey, result)
+  return result
+}
+
+export function getVisibleWallMaterials(wallNode: WallNode): WallMaterialArray {
+  return getMaterialsForWall(wallNode).visible
+}