fix nested top fill offsets

src/geo/polygons.js

@@ -61,6 +61,7 @@ const POLYS = {
     offset,
     outer,
     points,
+    print,
     rayIntersect,
     reconnect,
     renest,
@@ -212,6 +213,15 @@ export function renest(polygons, deep) {
     return nest(flatten(polygons, [], true), deep);
 }
 
+export function print(polys, pad = '  ', buf) {
+    buf = buf || [];
+    for (let poly of polys) {
+        buf.push(`${pad} - ${poly.points.length}`);
+        if (poly.inner) print(poly.inner, pad + pad, buf);
+    }
+    return buf;
+}
+
 /**
  * todo use clipper polytree?
  *

src/kiri/mode/fdm/work/post.js

@@ -758,6 +758,9 @@ export function layerProcessTop(z, top, count, offset1, offsetN, fillOffset, opt
         last = [top.poly];
     }
 
+    // renest deep because last[] could be nested
+    last = POLY.renest(last, true);
+
     // generate fill offset poly set from last offset to top.fill_off
     if (fillOffset && last.length > 0) {
         // if gaps present, remove that area from fill inset
@@ -766,7 +769,7 @@ export function layerProcessTop(z, top, count, offset1, offsetN, fillOffset, opt
             POLY.subtract(last, gaps, nulast, null, z);
             last = nulast;
         }
-        last.forEach(function(inner) {
+        last.forEach((inner) => {
             POLY.offset([inner], -fillOffset, {outs: top.fill_off, flat: true, z});
         });
     }

src/kiri/mode/fdm/work/slice.js

@@ -983,9 +983,9 @@ function layerRender(slice, params, opt = {}) {
         if (isThin && devel && top.fill_off?.length) {
             slice.output()
                 .setLayer('fill inset', Color.inset)
-                .addPolys(top.fill_off);
-                // .setLayer('last', { face: 0, line: 0x008888, check: 0x008888 })
-                // .addPolys(top.last);
+                .addPolys(top.fill_off)
+                .setLayer('last', { face: 0, line: 0x008888, check: 0x008888 })
+                .addPolys(top.last);
         }
     }