v1.6.1

package.json

@@ -1,6 +1,6 @@
 {
   "name": "d3-geo-polygon",
-  "version": "1.6.0",
+  "version": "1.6.1",
   "description": "Clipping and geometric operations for spherical polygons.",
   "keywords": [
     "d3",

src/clip/polygon.js

@@ -116,6 +116,21 @@ function interpolate(segments, polygon) {
           point = spherical(direction > 0 ? segment.to : segment.from);
         stream.point(point[0], point[1]);
       }
+    } else if (
+      from.index === to.index &&
+      from.t > to.t &&
+      from.index != null &&
+      to.index != null
+    ) {
+      for (
+        i = 0;
+        i < segments.length;
+        i++
+      ) {
+        segment = segments[(from.index + i * direction + segments.length)%segments.length],
+          point = spherical(direction > 0 ? segment.to : segment.from);
+        stream.point(point[0], point[1]);
+      }
     }
   };
 }

test/clip/polygon-test.js

@@ -11,3 +11,18 @@ tape("clipPolygon clips line", function(test) {
   test.end();
 });
 
+
+tape("clipPolygon interpolates when the intersections are on the same segment", function(test) {
+  var clipPolygon = d3.geoClipPolygon({
+    type: "Polygon",
+    coordinates: [[[-10, -11], [10, 10], [11, -10], [-10, -11]]]
+  }),
+    projection = d3_geo.geoEquirectangular().preclip(clipPolygon).precision(0.1),
+    path = d3_geo.geoPath().projection(projection);
+  test.equal(path({
+    type: "Polygon",
+    coordinates: [[[0, -11], [1, -11], [1, -10], [0, -10], [0, -11]]]
+  }).replace(/[.]\d+/g, ""),
+  "M482,278L482,276L480,276L480,278L466,279L453,279L506,223L509,276L495,277Z");
+  test.end();
+});