revert changes

src/geo/polygons.js

@@ -620,18 +620,14 @@ function offset(polys, dist, opts = {}) {
         }
     }
 
-    let { 
-        count = 1,
-        depth = 0,
-        fill = FillNonZero,
-        join = JoinType.jtMiter,
-        type = EndType.etClosedPolygon,
-    } = opts;
-
     let orig = polys,
+        count = numOrDefault(opts.count, 1),
+        depth = numOrDefault(opts.depth, 0),
         clean = opts.clean !== false,
         simple = opts.simple !== false,
-
+        fill = numOrDefault(opts.fill, FillNonZero),
+        join = numOrDefault(opts.join, JoinType.jtMiter),
+        type = numOrDefault(opts.type, EndType.etClosedPolygon),
         // if dist is array with values, shift out next offset
         offs = Array.isArray(dist) ? (dist.length > 1 ? dist.shift() : dist[0]) : dist,
         mina = numOrDefault(opts.minArea, 0.1),
@@ -667,7 +663,11 @@ function offset(polys, dist, opts = {}) {
 
     // if specified, perform offset gap analysis
     if (opts.gaps && polys.length) {
+        let oneg = offset(polys, -offs, {
+            fill: opts.fill, join: opts.join, type: opts.type, z: opts.z, minArea: mina
+        });
         let suba = [];
+        let diff = subtract(orig, oneg, suba, null, zed);
         opts.gaps.append(suba, opts.flat);
     }
 
@@ -678,14 +678,6 @@ function offset(polys, dist, opts = {}) {
 
     // if specified, perform up to *count* successive offsets
     if (polys.length) {
-        // decrement count, increment depth
-        opts.count = --count;
-        opts.depth = ++depth;
-        
-        //set poly depth
-        polys.forEach(p => {
-            p.depth = depth;
-        });
         // ensure opts has offset accumulator array
         opts.outs = opts.outs || [];
         // store polys in accumulator
@@ -696,6 +688,9 @@ function offset(polys, dist, opts = {}) {
         }
         // check for more offsets
         if (count > 1) {
+            // decrement count, increment depth
+            opts.count = count - 1;
+            opts.depth = depth + 1;
             // call next offset
             offset(polys, dist, opts);
         }