Refactor guide UI state and slab rendering

2026-05-01 00:33:57 +05:30
parent 1dc9ea0ba8
commit 3df3d12f46
9 changed files with 172 additions and 108 deletions
@@ -0,0 +1,67 @@
+import type { SlabNode } from '../schema'
+import { insetPolygonFromCentroid, simplifyClosedPolygon } from './polygon-geometry'
+
+/** Half of default wall thickness — used to extend slab geometry under walls */
+const SLAB_OUTSET = 0.05
+const AUTO_SLAB_INSET = 0.02
+const AUTO_SLAB_SIMPLIFY_TOLERANCE = 0.08
+
+export function getRenderableSlabPolygon(slabNode: SlabNode): Array<[number, number]> {
+  return slabNode.autoFromWalls
+    ? simplifyClosedPolygon(
+        insetPolygonFromCentroid(slabNode.polygon, AUTO_SLAB_INSET),
+        AUTO_SLAB_SIMPLIFY_TOLERANCE,
+      )
+    : outsetPolygon(slabNode.polygon, SLAB_OUTSET)
+}
+
+/**
+ * Expand a polygon outward by a uniform distance.
+ * Offsets each edge outward then intersects consecutive offset edges.
+ */
+function outsetPolygon(polygon: Array<[number, number]>, amount: number): Array<[number, number]> {
+  const n = polygon.length
+  if (n < 3) return polygon
+
+  // Determine winding via signed area
+  let area2 = 0
+  for (let i = 0; i < n; i++) {
+    const j = (i + 1) % n
+    area2 += polygon[i]![0] * polygon[j]![1] - polygon[j]![0] * polygon[i]![1]
+  }
+  const s = area2 >= 0 ? 1 : -1
+
+  // Offset each edge outward by amount
+  const offEdges: Array<[number, number, number, number]> = []
+  for (let i = 0; i < n; i++) {
+    const j = (i + 1) % n
+    const dx = polygon[j]![0] - polygon[i]![0]
+    const dz = polygon[j]![1] - polygon[i]![1]
+    const len = Math.sqrt(dx * dx + dz * dz)
+    if (len < 1e-9) {
+      offEdges.push([polygon[i]![0], polygon[i]![1], dx, dz])
+      continue
+    }
+    const nx = ((s * dz) / len) * amount
+    const nz = ((s * -dx) / len) * amount
+    offEdges.push([polygon[i]![0] + nx, polygon[i]![1] + nz, dx, dz])
+  }
+
+  // Intersect consecutive offset edges to get new vertices
+  const result: Array<[number, number]> = []
+  for (let i = 0; i < n; i++) {
+    const j = (i + 1) % n
+    const [ax, az, adx, adz] = offEdges[i]!
+    const [bx, bz, bdx, bdz] = offEdges[j]!
+    const denom = adx * bdz - adz * bdx
+    if (Math.abs(denom) < 1e-9) {
+      // Parallel edges — use offset endpoint
+      result.push([ax + adx, az + adz])
+    } else {
+      const t = ((bx - ax) * bdz - (bz - az) * bdx) / denom
+      result.push([ax + t * adx, az + t * adz])
+    }
+  }
+
+  return result
+}