Implement two-phase cut path generation, cut all copper in a single path

lib/ConvertContext.ts

@@ -16,5 +16,8 @@ export interface ConvertContext {
 
   netGeoms: Map<ConnectivityMapKey, Array<Polygon | Box>>
 
+  copperLayerPolygons: Polygon[]
+  boardCutPolygons: Polygon[]
+
   origin: { x: number; y: number }
 }

lib/element-handlers/addPcbBoard/index.ts

@@ -1,11 +1,9 @@
 import { Polygon, point } from "@flatten-js/core"
 import type { PcbBoard } from "circuit-json"
-import { ShapePath } from "lbrnts"
 import type { ConvertContext } from "../../ConvertContext"
-import { polygonToShapePathData } from "../../polygon-to-shape-path"
 
 export const addPcbBoard = (board: PcbBoard, ctx: ConvertContext) => {
-  const { origin, project, throughBoardCutSetting } = ctx
+  const { origin, boardCutPolygons } = ctx
 
   let polygon: Polygon | null = null
 
@@ -37,14 +35,5 @@ export const addPcbBoard = (board: PcbBoard, ctx: ConvertContext) => {
 
   if (!polygon) return
 
-  const { verts, prims } = polygonToShapePathData(polygon)
-
-  project.children.push(
-    new ShapePath({
-      cutIndex: throughBoardCutSetting.index,
-      verts,
-      prims,
-      isClosed: true,
-    }),
-  )
+  boardCutPolygons.push(polygon)
 }

lib/index.ts

@@ -61,6 +61,8 @@ export const convertCircuitJsonToLbrn = (
     throughBoardCutSetting,
     connMap,
     netGeoms: new Map(),
+    copperLayerPolygons: [],
+    boardCutPolygons: [],
     origin,
   }
 
@@ -111,7 +113,8 @@ export const convertCircuitJsonToLbrn = (
   //   }
   // }
 
-  // Create a union of all the net geoms, and add to project
+  // Phase 1: Construct flattenjs polygons for each cutting layer
+  // Create a union of all the net geoms and collect polygons for the copper layer
   for (const net of Object.keys(connMap.netMap)) {
     const netGeoms = ctx.netGeoms.get(net)!
 
@@ -137,18 +140,47 @@ export const convertCircuitJsonToLbrn = (
     // }
 
     for (const island of union.splitToIslands()) {
-      // Convert the polygon to verts and prims
-      const { verts, prims } = polygonToShapePathData(island)
-
-      project.children.push(
-        new ShapePath({
-          cutIndex: copperCutSetting.index,
-          verts,
-          prims,
-          isClosed: false,
-        }),
-      )
+      ctx.copperLayerPolygons.push(island)
     }
   }
+  // Phase 2: Construct a single cut path for each cutting layer
+
+  if (ctx.copperLayerPolygons.length > 0) {
+    const [firstCopper, ...restCopper] = ctx.copperLayerPolygons
+    let copperUnion: Polygon = firstCopper!
+    for (const poly of restCopper) {
+      copperUnion = BooleanOperations.unify(copperUnion, poly)
+    }
+
+    const { verts, prims } = polygonToShapePathData(copperUnion)
+
+    project.children.push(
+      new ShapePath({
+        cutIndex: copperCutSetting.index,
+        verts,
+        prims,
+        isClosed: false,
+      }),
+    )
+  }
+
+  if (ctx.boardCutPolygons.length > 0) {
+    const [firstBoard, ...restBoards] = ctx.boardCutPolygons
+    let boardUnion: Polygon = firstBoard!
+    for (const poly of restBoards) {
+      boardUnion = BooleanOperations.unify(boardUnion, poly)
+    }
+
+    const { verts, prims } = polygonToShapePathData(boardUnion)
+
+    project.children.push(
+      new ShapePath({
+        cutIndex: throughBoardCutSetting.index,
+        verts,
+        prims,
+        isClosed: true,
+      }),
+    )
+  }
   return project
 }