diff -r efd9c589177a -r c0b4a8b5a012 toolkit/javascript/d3/src/geom/delaunay.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/src/geom/delaunay.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,31 @@
+/**
+* @param vertices [[x1, y1], [x2, y2], …]
+* @returns triangles [[[x1, y1], [x2, y2], [x3, y3]], …]
+ */
+d3.geom.delaunay = function(vertices) {
+  var edges = vertices.map(function() { return []; }),
+      triangles = [];
+
+  // Use the Voronoi tessellation to determine Delaunay edges.
+  d3_voronoi_tessellate(vertices, function(e) {
+    edges[e.region.l.index].push(vertices[e.region.r.index]);
+  });
+
+  // Reconnect the edges into counterclockwise triangles.
+  edges.forEach(function(edge, i) {
+    var v = vertices[i],
+        cx = v[0],
+        cy = v[1];
+    edge.forEach(function(v) {
+      v.angle = Math.atan2(v[0] - cx, v[1] - cy);
+    });
+    edge.sort(function(a, b) {
+      return a.angle - b.angle;
+    });
+    for (var j = 0, m = edge.length - 1; j < m; j++) {
+      triangles.push([v, edge[j], edge[j + 1]]);
+    }
+  });
+
+  return triangles;
+};