Adjust threshold for distortion resampling.

Includes test case.

d3.js

@@ -5775,7 +5775,7 @@
       var dx = x1 - x0, dy = y1 - y0, distance2 = dx * dx + dy * dy;
       if (distance2 > 4 * δ2 && depth--) {
         var a = a0 + a1, b = b0 + b1, c = c0 + c1, m = Math.sqrt(a * a + b * b + c * c), φ2 = Math.asin(c /= m), λ2 = Math.abs(Math.abs(c) - 1) < ε ? (λ0 + λ1) / 2 : Math.atan2(b, a), p = projectPoint(λ2, φ2), x2 = p[0], y2 = p[1], dx2 = x2 - x0, dy2 = y2 - y0, dz = dy * dx2 - dx * dy2;
-        if (dz * dz / distance2 > δ2 || Math.abs((dx * dx2 + dy * dy2) / distance2 - .5) > .4) {
+        if (dz * dz / distance2 > δ2 || Math.abs((dx * dx2 + dy * dy2) / distance2 - .5) > .3) {
           resampleLineTo(x0, y0, λ0, a0, b0, c0, x2, y2, λ2, a /= m, b /= m, c, depth, listener);
           listener.point(x2, y2);
           resampleLineTo(x2, y2, λ2, a, b, c, x1, y1, λ1, a1, b1, c1, depth, listener);

src/geo/resample.js

@@ -98,7 +98,7 @@ function d3_geo_resample(projectPoint) {
           dx2 = x2 - x0,
           dy2 = y2 - y0,
           dz = dy * dx2 - dx * dy2;
-      if (dz * dz / distance2 > δ2 || (Math.abs((dx * dx2 + dy * dy2) / distance2 - .5) > .4)) {
+      if (dz * dz / distance2 > δ2 || Math.abs((dx * dx2 + dy * dy2) / distance2 - .5) > .3) {
         resampleLineTo(x0, y0, λ0, a0, b0, c0, x2, y2, λ2, a /= m, b /= m, c, depth, listener);
         listener.point(x2, y2);
         resampleLineTo(x2, y2, λ2, a, b, c, x1, y1, λ1, a1, b1, c1, depth, listener);

test/geo/path-test.js

@@ -627,7 +627,7 @@ suite.addBatch({
         ]);
       }
     },
-    "albers.precision(1)": {
+    "resampling near poles": {
       topic: function() {
         return d3.geo.path()
             .context(testContext)
@@ -636,11 +636,20 @@ suite.addBatch({
               .rotate([0, 0])
               .precision(1));
       },
-      "resampling near poles": function(path) {
+      "rotate([0, 0])": function(path) {
         path({type: "LineString", coordinates: [[0, 88], [180, 89]]});
         assert.isTrue(testContext.buffer().filter(function(d) { return d.type === "lineTo"; }).length > 1);
         path({type: "LineString", coordinates: [[180, 90], [1, 89.5]]});
         assert.isTrue(testContext.buffer().filter(function(d) { return d.type === "lineTo"; }).length > 1);
+      },
+      "rotate([11.5, 285])": function(path) {
+        try {
+          path.projection().rotate([11.5, 285]);
+          path({type: "LineString", coordinates: [[170, 20], [170, 0]]});
+          assert.isTrue(testContext.buffer().filter(function(d) { return d.type === "lineTo"; }).length > 1);
+        } finally {
+          path.projection().rotate([0, 0]);
+        }
       }
     },
     "rotate([0, 0, 0])": {